Endogenous Androgen Deficiency Enhances Diet-Induced Hypercholesterolemia and Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient Mice

BackgroundDespite numerous clinical and animal studies, the role of sex steroid hormones on lipoprotein metabolism and atherosclerosis remain controversial.ObjectiveWe sought to determine the effects of endogenous estrogen and testosterone on lipoprotein levels and atherosclerosis using mice fed a low-fat diet with no added cholesterol.MethodsMale and female low-density lipoprotein receptor-deficient mice were fed an open stock low-fat diet (10% of kcals from fat) for 2, 4, or 17 weeks. Ovariectomy, orchidectomy, or sham surgeries were performed to evaluate the effects of the presence or absence of endogenous hormones on lipid levels, lipoprotein distribution, and atherosclerosis development.ResultsFemale mice fed the study diet for 17 weeks had a marked increase in levels of total cholesterol, triglycerides, apolipoprotein-B containing lipoproteins, and atherosclerosis compared with male mice. Surprisingly, ovariectomy in female mice had no effect on any of these parameters. In contrast, castration of male mice markedly increased total cholesterol concentrations, triglycerides, apolipoprotein B-containing lipoproteins, and atherosclerotic lesion formation compared with male and female mice.ConclusionsThese data suggest that endogenous androgens protect against diet-induced increases in cholesterol concentrations, formation of proatherogenic lipoproteins, and atherosclerotic lesions formation. Conversely orchidectomy, which decreases androgen concentrations, promotes increases in cholesterol concentrations, proatherogenic lipoprotein formation, and atherosclerotic lesion formation in low-density lipoprotein receptor-deficient mice in response to a low-fat diet.     

Amyotrophic lateral sclerosis is associated with hypolipidemia at the presymptomatic stage in mice

Objective

To demonstrate that hypolipidemia is a typical feature of the mouse model of amyotrophic lateral sclerosis (ALS) and to assess the association between hypolipidemia and disease stage, dietary intake, and sex.

Methods

We compared daily dietary intake, body weight, and serumlipid and glucose levels in ALS mice and wild-type controls at different stages of the disease.

Findings

Total cholesterol low-density lipoprotein (LDL) and LDL/high-density lipoprotein (HDL) ratio were significantly lower in ALS mice compared with controls. Subgroup analysis revealed that the incidence of hypolipidemia was significantly greater in male, but not female, ALS mice compared with control mice and that hypolipidemia was present at the presymptomatic stage of the disease. This hypolipidemia can be found without a decrease in the serum levels of other energy sources, such as glucose, in the presymptomatic stage.

Conclusions

Hypolipidemia is present at the presymptomatic stage of the ALS mouse model in the absence of malnutrition, significant neuromuscular degeneration or regeneration, and respiratory difficulty. Our findings suggest that hypolipidemia might be associated with the pathomechanism of ALS and/or lipid-specific metabolism rather than simply an epiphenomenon of neuromuscular degeneration or energy imbalance.     

Castration attenuates myelin repair following lysolecithin induced demyelination in rat optic chiasm: an evaluation using visual evoked potential, marker genes expression and myelin staining

Multiple sclerosis (MS) is a demyelinating disease that affects the central nervous system. MS is the most common neurological disorder in young adults with a greater incidence among females. Male gonadal hormones have a protective effect on neural system development and myelin maturation. In this study, we investigate the effect of castration on lysolecithin-induced demyelination and remyelination processes using visual evoked potentials, in addition to measuring the expressions of Olig2, MBP, Nogo-A and GFAP mRNAs as oligodendrocyte or astrocyte markers; and histological assessments by myelin-specific staining. We observed more expanded demyelination with delayed repair process in castrated rats. Expression levels of the aforementioned marker genes confirmed histological and electrophysiological observations. Our results showed a pivotal role for endogenous male hormones in the context of demyelinating insults. It may also account for the different prognosis of MS between male and female genders and provide new insights for therapeutic treatments.     

The Extracellular Domain of Neurotrophin Receptor p75 as a Candidate Biomarker for Amyotrophic Lateral Sclerosis

Objective biomarkers for amyotrophic lateral sclerosis would facilitate the discovery of new treatments. The common neurotrophin receptor p75 is up regulated and the extracellular domain cleaved from injured neurons and peripheral glia in amyotrophic lateral sclerosis. We have tested the hypothesis that urinary levels of extracellular neurotrophin receptor p75 serve as a biomarker for both human motor amyotrophic lateral sclerosis and the SOD1^G93A mouse model of the disease. The extracellular domain of neurotrophin receptor p75 was identified in the urine of amyotrophic lateral sclerosis patients by an immuno-precipitation/western blot procedure and confirmed by mass spectrometry. An ELISA was established to measure urinary extracellular neurotrophin receptor p75. The mean value for urinary extracellular neurotrophin receptor p75 from 28 amyotrophic lateral sclerosis patients measured by ELISA was 7.9±0.5 ng/mg creatinine and this was significantly higher (p<0.001) than 12 controls (2.6±0.2 ng/mg creatinine) and 19 patients with other neurological disease (Parkinson''s disease and Multiple Sclerosis; 4.1±0.2 ng/mg creatinine). Pilot data of disease progression rates in 14 MND patients indicates that p75NTR^ECD levels were significantly higher (p = 0.0041) in 7 rapidly progressing patients as compared to 7 with slowly progressing disease. Extracellular neurotrophin receptor p75 was also readily detected in SOD1^G93A mice by immuno-precipitation/western blot before the onset of clinical symptoms. These findings indicate a significant relation between urinary extracellular neurotrophin receptor p75 levels and disease progression and suggests that it may be a useful marker of disease activity and progression in amyotrophic lateral sclerosis.     

The crucial role of caspase-9 in the disease progression of a transgenic ALS mouse model

Mutant copper/zinc superoxide dismutase (SOD1)-overexpressing transgenic mice, a mouse model for familial amyotrophic lateral sclerosis (ALS), provides an excellent resource for developing novel therapies for ALS. Several observations suggest that mitochondria-dependent apoptotic signaling, including caspase-9 activation, may play an important role in mutant SOD1-related neurodegeneration. To elucidate the role of caspase-9 in ALS, we examined the effects of an inhibitor of X chromosome-linked inhibitor of apoptosis (XIAP), a mammalian inhibitor of caspase-3, -7 and -9, and p35, a baculoviral broad caspase inhibitor that does not inhibit caspase-9. When expressed in spinal motor neurons of mutant SOD1 mice using transgenic techniques, XIAP attenuated disease progression without delaying onset. In contrast, p35 delayed onset without slowing disease progression. Moreover, caspase-9 was activated in spinal motor neurons of human ALS subjects. These data strongly suggest that caspase-9 plays a crucial role in disease progression of ALS and constitutes a promising therapeutic target.     

Influence of Methylene Blue on Microglia-Induced Inflammation and Motor Neuron Degeneration in the SOD1(G93A) Model for ALS

Mutations in SOD1 cause hereditary variants of the fatal motor neuron disease amyotrophic lateral sclerosis (ALS). Pathophysiology of the disease is non-cell-autonomous, with toxicity deriving also from glia. In particular, microglia contribute to disease progression. Methylene blue (MB) inhibits the effect of nitric oxide, which mediates microglial responses to injury. In vivo 2P-LSM imaging was performed in ALS-linked transgenic SOD1(G93A) mice to investigate the effect of MB on microglia-mediated inflammation in the spinal cord. Local superfusion of the lateral spinal cord with MB inhibited the microglial reaction directed at a laser-induced axon transection in control and SOD1(G93A) mice. In vitro, MB at high concentrations inhibited cytokine and chemokine release from microglia of control and advanced clinical SOD1(G93A) mice. Systemic MB-treatment of SOD1(G93A) mice at early preclinical stages significantly delayed disease onset and motor dysfunction. However, an increase of MB dose had no additional effect on disease progression; this was unexpected in view of the local anti-inflammatory effects. Furthermore, in vivo imaging of systemically MB-treated mice also showed no alterations of microglia activity in response to local lesions. Thus although systemic MB treatment had no effect on microgliosis, instead, its use revealed an important influence on motor neuron survival as indicated by an increased number of lumbar anterior horn neurons present at the time of disease onset. Thus, potentially beneficial effects of locally applied MB on inflammatory events contributing to disease progression could not be reproduced in SOD1(G93A) mice via systemic administration, whereas systemic MB application delayed disease onset via neuroprotection.     

Metformin treatment has no beneficial effect in a dose-response survival study in the SOD1(G93A) mouse model of ALS and is harmful in female mice

Background

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurological disorder characterized by selective degeneration of upper and lower motor neurons. The primary triggers for motor neuron degeneration are unknown but inflammation, oxidative stress and mitochondrial defects have been identified as potential contributing factors. Metformin is an anti-type II diabetes drug that has anti-inflammatory and anti-oxidant properties, can bring about mitochondrial biogenesis and has been shown to attenuate pathology in mouse models of Huntington''s disease and multiple sclerosis. We therefore hypothesized that it might increase survival in the SOD1^G93A murine model of ALS.

Methodology/Principal Findings

Treatment of male and female SOD1^G93A mice (n = ≥6 per sex) with 2 mg/ml metformin in the drinking water from 35 days, resulted in a significant increase in motor unit survival, as measured by in vivo electrophysiology at 100 days, in male EDL muscles (24+/−2 vs. 14+/−2 motor units, p<0.005) and female TA muscles (21+/−1 vs. 15+/−2 motor units, P = 0.0134). We therefore continued to test the effect of 0.5, 2 and 5 mg/ml metformin in the drinking water from 35 days on disease onset and progression (identified by twice weekly determination of weight and neurological score) as well as survival in male and female SOD1^G93A mice (n = ≥14 per sex). Results for all groups were compared using Kaplan-Meier time to event analyses. In this survival study, metformin was unable to reduce pathology at any dose and had an unexpected dose-dependent negative effect on the onset of neurological symptoms (P = 0.0236) and on disease progression (P = 0.0362) in female mice.

Conclusions/Significance

This study suggests that metformin is a poor candidate for clinical trial in ALS patients and that the possibility of harmful effects of metformin in female ALS patients with type II diabetes should be investigated.     

Effect of testosterone on the susceptibility of C57BL/6 mice to infection with Brugia pahangi with reference to inflammatory cell response

Effects of testosterone on the susceptibility and inflammatory cell responses of C57BL/6 mice infected intraperitoneally with Brugia pahangi larvae were examined. On day 15 postinfection, female mice showed significantly greater resistance than did males, and peritoneal cell responses (lymphocytes, macrophages, and eosinophils) were great in females. Castration of highly susceptible male mice increased their resistance and peritoneal cell responses to the level of female mice; whereas, castration of female mice did not affect the susceptibility and cell responses. Furthermore, testosterone treatment at a physiological dose in the castrated male mice or a pharmacological dose in female mice suppressed resistance and inflammatory cell responses. These results suggest that male sex hormone, testosterone, but not female sex hormone has a regulatory role in the susceptibility and cellular response of C57BL/6 mice to infection with B. pahangi, and it causes differences between sexes in susceptibility.     

Ablation of proliferating cells in the CNS exacerbates motor neuron disease caused by mutant superoxide dismutase

Proliferation of glia and immune cells is a common pathological feature of many neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Here, to investigate the role of proliferating cells in motor neuron disease, SOD1(G93A) transgenic mice were treated intracerebroventicularly (i.c.v.) with the anti-mitotic drug cytosine arabinoside (Ara-C). I.c.v. delivery of Ara-C accelerated disease progression in SOD1(G93A) mouse model of ALS. Ara-C treatment caused substantial decreases in the number of microglia, NG2+ progenitors, Olig2+ cells and CD3+ T cells in the lumbar spinal cord of symptomatic SOD1(G93A) transgenic mice. Exacerbation of disease was also associated with significant alterations in the expression inflammatory molecules IL-1β, IL-6, TGF-β and the growth factor IGF-1.     

Mitochondrial dysfunction in amyotrophic lateral sclerosis

The etiology of motor neuron degeneration in amyotrophic lateral sclerosis (ALS) remains to be better understood. Based on the studies from ALS patients and transgenic animal models, it is believed that ALS is likely to be a multifactorial and multisystem disease. Many mechanisms have been postulated to be involved in the pathology of ALS, such as oxidative stress, glutamate excitotoxicity, mitochondrial damage, defective axonal transport, glia cell pathology and aberrant RNA metabolism. Mitochondria, which play crucial roles in excitotoxicity, apoptosis and cell survival, have shown to be an early target in ALS pathogenesis and contribute to the disease progression. Morphological and functional defects in mitochondria were found in both human patients and ALS mice overexpressing mutant SOD1. Mutant SOD1 was found to be preferentially associated with mitochondria and subsequently impair mitochondrial function. Recent studies suggest that axonal transport of mitochondria along microtubules and mitochondrial dynamics may also be disrupted in ALS. These results also illustrate the critical importance of maintaining proper mitochondrial function in axons and neuromuscular junctions, supporting the emerging “dying-back” axonopathy model of ALS. In this review, we will discuss how mitochondrial dysfunction has been linked to the ALS variants of SOD1 and the mechanisms by which mitochondrial damage contributes to the disease etiology.     

Structural and thermodynamic effects of post-translational modifications in mutant and wild type Cu, Zn superoxide dismutase

Aggregation of Cu,Zn superoxide dismutase (SOD1) is implicated in amyotrophic lateral sclerosis. Glutathionylation and phosphorylation of SOD1 is omnipresent in the human body, even in healthy individuals, and has been shown to increase SOD1 dimer dissociation, which is the first step on the pathway toward SOD1 aggregation. We found that post-translational modification of SOD1, especially glutathionylation, promotes dimer dissociation. We discovered an intermediate state in the pathway to dissociation, a conformational change that involves a “loosening” of the β-barrels and a loss or shift of dimer interface interactions. In modified SOD1, this intermediate state is stabilized as compared to unmodified SOD1. The presence of post-translational modifications could explain the environmental factors involved in the speed of disease progression. Because post-translational modifications such as glutathionylation are often induced by oxidative stress, post-translational modification of SOD1 could be a factor in the occurrence of sporadic cases of amyotrophic lateral sclerosis, which represent 90% of all cases of the disease.     

Gender and human chronic renal disease

Background: Gender affects the incidence, prevalence, and progression of renal disease. In animal models of the disease, female sex appears to modify the course of progression. Hormonal manipulation by male or female castration also changes the course of renal disease progression, suggesting direct effects of sex hormones in influencing the course of these maladies.Objective: This review examines the pertinent animal and human studies assessing the role of gender, and strives to shed light on the possible physiologic mechanisms underlying the effect of gender, on renal disease progression.Methods: A summary and evaluation of past and recent studies describing the rate of renal disease progression in animal models and humans as it pertains to gender is provided. In addition, studies elucidating the factors involved in the more modest renal progression rate in females are reviewed and conclusions drawn. Relevant English-language publications were identified by searching the PubMed database from January 1990 until November 2007 using the search terms gender, sex, renal disease, and kidney.Results: In polycystic kidney disease, membranous nephropathy, immunoglobulin A nephropathy, and “chronic renal disease of unknown etiology,” men progress at a faster rate to end-stage renal failure than do women. In type 1 diabetes mellitus, there is evidence that males are more likely to manifest signs of renal disease, such as proteinuria. The factors involved in this gender disparity may include diet, kidney and glomerular size, differences in glomerular hemodynamics, and the direct effects of sex hormones. In many, but not all, animal models of renal disease, estrogens slow progression rate. Several studies have recently evaluated the effect of selective estrogen receptor modulators on renal function in humans.Conclusion: Further studies assessing the factors involved in the gender disparity in renal disease progression and the effects of hormonal treatments are warranted.     

Muscle expression of a local Igf-1 isoform protects motor neurons in an ALS mouse model

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by a selective degeneration of motor neurons, atrophy, and paralysis of skeletal muscle. Although a significant proportion of familial ALS results from a toxic gain of function associated with dominant SOD1 mutations, the etiology of the disease and its specific cellular origins have remained difficult to define. Here, we show that muscle-restricted expression of a localized insulin-like growth factor (Igf) -1 isoform maintained muscle integrity and enhanced satellite cell activity in SOD1(G93A) transgenic mice, inducing calcineurin-mediated regenerative pathways. Muscle-specific expression of local Igf-1 (mIgf-1) isoform also stabilized neuromuscular junctions, reduced inflammation in the spinal cord, and enhanced motor neuronal survival in SOD1(G93A) mice, delaying the onset and progression of the disease. These studies establish skeletal muscle as a primary target for the dominant action of inherited SOD1 mutation and suggest that muscle fibers provide appropriate factors, such as mIgf-1, for neuron survival.     

SEXUAL DIMORPHISM IN MAMMALS

1. Life expectancy and mortality rates from diseases arising in various organs vary with sex because of differential exposure to external hazards and because of essential differences between males and females in aspects not directly connected with reproduction. This review attempts to collate data about the structural and functional dimorphism of mammals exclusive of the genital organs and psychological aspects. 2. The primary sex ratio is not certain and like the secondary and tertiary may vary with species. In many mammals more males are aborted and born than females. Later a higher mortality of males, due to sex-linked congenital diseases and greater exposure to external hazards, shifts the balance in favour of females at the time of sexual maturity. The average life span of females is longer than that of males, except in hamsters and in inbred strains of mice with a high incidence of mammary tumours. 3. Chromosomes as well as gonadal hormones are responsible for the development of male and female characteristics. The Y-chromosome initiates the differentiation of the testis, but gonadal hormones control the subsequent differentiation of the genital tract and other organs. In embryos the testicular secretion precedes that of the ovary. The Y-chromosome is devoid of, but the X-chromosome retains structural genes. The random heterochromatization of a paternal or a maternal X-chromosome in the somatic cells of female embryos equalizes the genetic information for both sexes and produces a mosaicism of female somatic cells except in the kangaroo where the paternal X-chromosome is selectively inactivated. Deficient genes on the X-chromosome become manifest in hemizygous males, in homozygous females and can be detected in heterozygous women in half of the somatic cell population in some conditions. 4. The testis grows faster than the ovary and starts to secrete earlier, but the maturation of female gonocytes precedes that of males. Spermatogenesis starts at puberty and is maintained throughout life, while multiplication of oogonia ceases in the perinatal period (except in lemurs), when the stage of the first meiotic division is reached. The stock of oocytes dwindles during life. 5. In many mammals the male grows faster than the female before and after birth, but is less mature. Puberty tends to start earlier in females and the associated growth spurt does not last as long as in males. Testosterone has a direct anabolic effect, promotes growth and delays differentiation. Oestrogens are considered katabolic, but promote growth indirectly by stimulating the production of growth hormone in the pituitary. Progesterone has an anabolic and slight androgenic effect. 6. A female pattern of differentiation of the hypothalamus, the pituitary and the pineal gland, manifested at puberty by cyclical activities of the reproductive organs requires the absence of androgens during a critical phase of ante- or perinatal development. Oestrogens given to males at that period produce effects similar to castration. Antiandrogens induce in males a cyclical pattern of function in the hypothalamus and the pituitary, enlargement of the breasts and formation of nipples in the rat and a female type of sexual behaviour. There is no complete sex reversal in mammals comparable to that of fish and amphibians. 7. With some exceptions (hamsters, rabbits, guinea-pigs) males are larger than females. Gender differences in weight of organs and in other parameters must be assessed as proportion to male or female weight, surface and activities. The relatively greater amount of fat in female and of connective tissue in male organs in relation to the active parenchyma complicate comparisons. 8. The head and shoulder region is proportionately larger in males and the pelvic region in females. Men and male mice have heavier bones, muscles, hearts, lungs, salivary glands, kidneys and gonads in proportion to body weight, while females have proportionately heavier brains, livers, spleens, adrenals, thymus, stomach and fat deposits. 9. The basal metabolic rate in women is lower than in males. A great variety of metabolic parameters, levels of enzyme activity, location of fat deposits, sensitivity to drugs is sexually dimorphic and responsive to the action of androgens, oestrogens and progestagens. 10. Males tend to have more red blood corpuscles, haemoglobin and erythropoietin per unit volume of blood than women, cows, mares, sows, bitches, female cats and hamsters, but there is no sex difference in this respect in rats, rabbits, goats or sheep. Females tend to have more granulocytes and a proportionately larger lymphomyeloid complex (bone marrow, spleen, thymus, lymph nodes and lymphoepithelial tissues) and greater immunological competence than males. The cortical epithelium of the thymus in mice and rats is sexually dimorphic, responsive to castration and treatment with sex hormones and varies with the oestrous cycle. 11. The kidney is proportionately larger in male mice, rats, cats and dogs, is reduced by castration and enlarged by treatment with testosterone. The kidneys of hamsters and guinea-pigs do not differ in size with sex, nor do they respond to castration or to androgens. The proportion of tubules to glomeruli is greater in the male than the female kidney. The tubular mass increases with androgenic medication, but not the juxtaglomerular apparatus. The parietal epithelium of Bowman's capsule, the histochemistry of the kidney and the composition of the urine vary with gender and respond to sex hormones according to species and strain. The bladder of male mice is proportionately larger than that of females. Some pheromones are present in the bladder urine of intact male mice and of spayed females given testosterone, but absent from that of castrated males. 12. Boars, male elephants, mastodons, horses, deer and monkeys have larger canines than the females. The submaxillary gland of male mice, rats and pigs is proportionately larger than in females, but smaller in hamsters. The proportion of mucous to serous acinar cells in female rodents is greater than in males; female hamsters produce more sialic acid. The secretory tubules of male rats and mice are larger than in females and produce a nerve- and an epidermal-growth factor. Apart from amylase the levels of enzyme activity vary with sex. The liver is sexually dimorphic as regards size, content and metabolism of glycogen, fat, vitamin A, levels of enzymatic activity, phagocytic activity and in its response to castration, sex hormones, to toxic agents, drugs and carcinogens. Sex hormones affect the production of insulin by the pancreas in vivo and in vitro. 13. The male larynx which enlarges and induces voice changes in many mammals at puberty or the onset of the breeding season, is affected by castration and by sex hormones. Male lungs are proportionately larger than female ones with a greater vital and maximal respiratory capacity. Breathing rate and manner varies with sex and is related to differences in the muscular development of the diaphragm. 14. The epidermis and dermis of males are thicker, but the subcutis thinner than in females. The skin is sexually dimorphic in respect of dermatoglyphics, the replacement of vellus by terminal hair and pigmentation of specific regions, the colour of the face and of the sexual skin in monkeys, the development of antlers and horns. The synchrony of the hair cycle and the growth wave of the hair coat in mice and rats depend on the sex of the animals. The X-chromosome mosaicism in the hair follicles of female mice accounts for the mosaicism in pigmentation. Apart from a genetic disorder, the sweat glands are not sexually dimorphic, but the apocrine, the sebaceous glands and their specialized forms are. The embryonic development of mammary glands depends on the absence of androgens and can be induced in male rats and guinea-pigs by antiandrogens. 15. An intact cerebral cortex is necessary for the performance of reproductive functions in male, but not in female rats, cats, rabbits and guinea-pigs. Removal of the olfactory bulb impairs reproduction in female, but not in male mice. Pinealectomy prevents the testicular atrophy of hamsters kept in the dark. The reproductive cycles in females are regulated by the hypothalamus through the control of the ratio of FSH to LH release in the pituitary. This in turn acts on the ovary and thus affects the activity of the thyroid, thymus and lung. In males FSH and LH act synergistically and their secretion is not controlled separately. Oestrogens are more effective than androgens in inhibiting pituitary functions. Sexual dimorphism in cytology, enzyme levels and oestrogen-binding is manifest in the preoptic area, the hypothalamus and the nucleus medialis amygdalae. The female brain is proportionately larger than the male with equal relative amounts of grey and white matter, but a bigger hypothalamic-pituitary-pineal complex. The pineal gland is more prone to tumour formation in boys than in girls and retains its cellularity longer in women than in men. Colour blindness is manifested less in heterozygous women than in hemizygous men. Mature women are more sensitive to the smell of synthetic musk than girls or men. Male rats and mice are more susceptible to audiogenic seizures than females. 16. The activity of the thyroid gland varies at different phases of the oestrous cycle in rats, mice and guinea-pigs. Female mice release more thyroid hormone into the blood than males or spayed animals. Oestrogens increase the level of thyroxin-binding protein. The concentration of TSH in the blood of mature women is double that of men and of menopausal women. The incidence of non-endemic thyroid disorders in women considerably exceeds that in men. 17. The adrenals of females are much larger than those of males except in hamsters. The gland of the female mouse contains more lipid than that of the male. The juxtamedullary X-zone of mice involutes at puberty in males and during the first pregnancy in females. Castration induces an X-zone in male mice, voles, hamsters and cats and an enlargement without stratification in rats. ACTH controls the secretion of glucocorticoids and since its formation is promoted by oestrogens and inhibited by androgens, sex hormones influence indirectly the size and activity of the adrenal cortex. Hepatic inactivation of glucocorticoids is 3 to 10 times greater in intact females than in males. 18. The implications of species variations in sexual dimorphism for the survival and the evolution of mammals are discussed.     

Possible modulation by male sex hormone of Th1/Th2 function in protection against Plasmodium chabaudi chabaudi AS infection in mice

Zhang, Z.-H., Chen, L., Saito, S., Kanagawa, O., and Sendo, F. 2000. Possible modulation by male sex hormone of Th1/Th2 function in protection against Plasmodium chabaudi chabaudi AS infection in mice. Experimental Parasitology 96, 121-129. We examined the mortality, survival time, and parasitemia in interferon gamma receptor (IFN-gamma R)-deficient (IFN-gamma R(-/-)) and IL-4-deficient (IL-4(-/-)) mice infected with Plasmodium chabaudi AS and compared them with the wild type counterparts (IFN-gamma R(+/+) and IL-4(+/+), respectively). (1) Mortality was higher and survival time was shorter in males of both IFN-gamma R(-/-) and IL-4(-/-) mice infected with P. chabaudi AS, compared with their wild type counterparts, whereas such a difference was not observed in female mice. (2) These differences between males and females were not observed when male mice were castrated; however, female castration had no effect on the data. (3) The rate of parasitemia in both male and female IFN-gamma R(-/-) and IL-4(-/-) mice was higher at some points during the observation than in the wild type counterparts. (4) These results on susceptibility vs resistance to P. chabaudi AS infection can be explained partially by the levels of expression of Th1/Th2 cytokine and chemokine mRNAs in the spleen cells of the infected mice. These results suggest that male sex hormones modulate the function of Th1/Th2 cells and that these T cells counteract the activity of these hormones in protection against P. chabaudi AS infection in mice.     

Replacement of microglial cells using Clodronate liposome and bone marrow transplantation in the central nervous system of SOD1(G93A) transgenic mice as an in vivo model of amyotrophic lateral sclerosis

Disease progression of amyotrophic lateral sclerosis (ALS) is partially mediated by the toxic microenvironment established by microglia. In the present study, we used SOD1G93A transgenic mice as an in vivo ALS model and replaced microglia expressing mutant SOD1 (mSOD1) with microglia expressing wild-type SOD1 (w/tSOD1) to modulate the toxic microenvironment. Stereotactic injection of Clodronate liposome, a selective toxin against the monocyte/macrophage system, into the fourth ventricle of the brains of 12-week-old asymptomatic ALS mice reduced the number of microglia effectively in the central nervous system. Subsequent bone marrow transplantation (BMT) with bone marrow cells (BMCs) expressing w/tSOD1 and GFP leads to replacement of the endogenous microglia of the ALS mice with microglia expressing w/tSOD1 and GFP. The expression of mSOD1 in the other neural cells was not influenced by the replacement procedures, and immunological side effects were not observed. The replacement of microglia significantly slowed disease progression and prolonged survival of the ALS mice compared with the ALS mice treated by stereotactic injection of PBS-liposome and BMT with BMCs expressing mSOD1 or w/tSOD1. These results suggest that replacement of microglia would improve the neural cell microenvironment, thereby slowing disease progression. The mechanisms and functional implications of this replacement require further elucidation.     

Spinal cord pathology is ameliorated by P2X7 antagonism in a SOD1-mutant mouse model of amyotrophic lateral sclerosis

In recent years there has been an increasing awareness of the role of P2X7, a receptor for extracellular ATP, in modulating physiopathological mechanisms in the central nervous system. In particular, P2X7 has been shown to be implicated in neuropsychiatry, chronic pain, neurodegeneration and neuroinflammation. Remarkably, P2X7 has also been shown to be a ‘gene modifier’ in amyotrophic lateral sclerosis (ALS): the receptor is upregulated in spinal cord microglia in human and rat at advanced stages of the disease; in vitro, activation of P2X7 exacerbates pro-inflammatory responses in microglia that have an ALS phenotype, as well as toxicity towards neuronal cells. Despite this detrimental in vitro role of P2X7, in SOD1-G93A mice lacking P2X7, the clinical onset of ALS was significantly accelerated and disease progression worsened, thus indicating that the receptor might have some beneficial effects, at least at certain stages of disease. In order to clarify this dual action of P2X7 in ALS pathogenesis, in the present work we used the antagonist Brilliant Blue G (BBG), a blood-brain barrier permeable and safe drug that has already been proven to reduce neuroinflammation in traumatic brain injury, cerebral ischemia-reperfusion, neuropathic pain and experimental autoimmune encephalitis. We tested BBG in the SOD1-G93A ALS mouse model at asymptomatic, pre-symptomatic and late pre-symptomatic phases of disease. BBG at late pre-onset significantly enhanced motor neuron survival and reduced microgliosis in lumbar spinal cord, modulating inflammatory markers such as NF-κB, NADPH oxidase 2, interleukin-1β, interleukin-10 and brain-derived neurotrophic factor. This was accompanied by delayed onset and improved general conditions and motor performance, in both male and female mice, although survival appeared unaffected. Our results prove the twofold role of P2X7 in the course of ALS and establish that P2X7 modulation might represent a promising therapeutic strategy by interfering with the neuroinflammatory component of the disease.KEY WORDS: ALS, Brilliant Blue G, Microglia, Motor neuron, P2X7     

Copy number variation in Y chromosome multicopy genes is linked to a paternal parent-of-origin effect on CNS autoimmune disease in female offspring

BackgroundThe prevalence of some autoimmune diseases is greater in females compared with males, although disease severity is often greater in males. The reason for this sexual dimorphism is unknown, but it may reflect negative selection of Y chromosome-bearing sperm during spermatogenesis or male fetuses early in the course of conception/pregnancy. Previously, we showed that the sexual dimorphism in experimental autoimmune encephalomyelitis (EAE) is associated with copy number variation (CNV) in Y chromosome multicopy genes. Here, we test the hypothesis that CNV in Y chromosome multicopy genes influences the paternal parent-of-origin effect on EAE susceptibility in female mice.ResultsWe show that C57BL/6 J consomic strains of mice possessing an identical X chromosome and CNV in Y chromosome multicopy genes exhibit sperm head abnormalities and female-biased sex ratio. This is consistent with X-Y intragenomic conflict arising from an imbalance in CNV between homologous X:Y chromosome multicopy genes. These males also display paternal transmission of EAE to female offspring and differential loading of microRNAs within the sperm nucleus. Furthermore, in humans, families of probands with multiple sclerosis similarly exhibit a female-biased sex ratio, whereas families of probands affected with non-sexually dimorphic autoimmune diseases exhibit unbiased sex ratios.ConclusionsThese findings provide evidence for a mechanism at the level of the male gamete that contributes to the sexual dimorphism in EAE and paternal parent-of-origin effects in female mice, raising the possibility that a similar mechanism may contribute to the sexual dimorphism in multiple sclerosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0591-7) contains supplementary material, which is available to authorized users.     

Astroglial inhibition of NF-κB does not ameliorate disease onset and progression in a mouse model for amyotrophic lateral sclerosis (ALS)

Motor neuron death in amyotrophic lateral sclerosis (ALS) is considered a "non-cell autonomous" process, with astrocytes playing a critical role in disease progression. Glial cells are activated early in transgenic mice expressing mutant SOD1, suggesting that neuroinflammation has a relevant role in the cascade of events that trigger the death of motor neurons. An inflammatory cascade including COX2 expression, secretion of cytokines and release of NO from astrocytes may descend from activation of a NF-κB-mediated pathway observed in astrocytes from ALS patients and in experimental models. We have attempted rescue of transgenic mutant SOD1 mice through the inhibition of the NF-κB pathway selectively in astrocytes. Here we show that despite efficient inhibition of this major pathway, double transgenic mice expressing the mutant SOD1(G93A) ubiquitously and the dominant negative form of IκBα (IκBαAA) in astrocytes under control of the GFAP promoter show no benefit in terms of onset and progression of disease. Our data indicate that motor neuron death in ALS cannot be prevented by inhibition of a single inflammatory pathway because alternative pathways are activated in the presence of a persistent toxic stimulus.