Alterations of brain endocannabinoidome signaling in germ-free mice

We investigated the hypothesis that the endocannabinoidome (eCBome), an extension of the endocannabinoid (eCB) signaling system with important functions in the CNS, may play a role in the microbiota-gut-brain axis. Using LC-MS/MS and qPCR arrays we profiled the brain eCBome of juvenile (4 weeks) and adult (13 weeks) male and female germ-free (GF) mice, which are raised in sterile conditions and virtually devoid of microbiota, present neurophysiological deficits, and were found recently to exhibit a strongly altered gut eCBome in comparison to conventionally raised age/sex-matched controls. The causal effect of the gut microbiome on the eCBome was investigated through the re-introduction into adult male GF mice of a functional gut microbiota by fecal microbiota transfer (FMT). The concentrations of the eCB, 2-arachidonoylglycerol (2-AG), and its 2-monoacylglycerol congeners, were significantly reduced in the brain, but not in the hypothalamus, of both juvenile and adult male and adult female GF mice. FMT rendered these decreases non-statistically significant. The eCB, anandamide (AEA), and its congener N-acylethanolamines (NAEs), were instead increased in the brain of adult female GF mice. Saturated fatty acid-containing NAEs were decreased in adult male GF mouse hypothalamus in a manner not reversed by FMT. Only few changes were observed in the expression of eCBome enzymes and receptors. Our data open the possibility that altered eCBome signaling may underlie some of the brain dysfunctions typical of GF mice.     

Dipetalonema viteae: Response of spleen cells in experimental mouse filariasis to mitogens and antigens

Balb/c mice were infected by transplanting 3, 5, 10, or 20 female adult Dipetalonema viteae under the dorsal skin. The microfilaremias resulting from infections with 3 or 5 adult worms were of lesser magnitude and of shorter duration than those produced in infections with 10 or 20 worms. Spleen cells taken from these mice at various intervals after infection were assayed in vitro for their ability to respond to phytohemagglutinin (PHA) or lipopolysaccharide (LPS). There was no depression in the response to LPS or to PHA in mice given infections of 3 or 5 D. viteae adult worms. In contrast, the response to PHA was significantly depressed in groups receiving 10 or 20 adult female worms 12 days after infection and by Day 25, the depression was severe. Thereafter the PHA responsiveness recovered gradually to reach control values on Day 60. In mice transplanted with 10 or 20 D. viteae adult worms there was no significant depression in the response to LPS at any time during the infection, but the response was increased slightly sporadically during infection. These results indicate that in mice, this infection causes an initial suppression in the function of PHA-sensitive T cells but has little effect on the B cells which respond to LPS. A factor present in serum taken on Day 25 from mice infected with 10 or 20 adult worms inhibited the proliferative response to PHA by spleen cells from normal mice. The recovery of PHA responsiveness in mice given the heavier infections coincided with death of the adult worms, but mitogen reactivity and microfilaremia were unrelated. Antigens from male or female worms induced cell division in spleen cells taken from infected mice after microfilaremia had ceased whether they were implanted with 3 or 10 adult worms.     

Chronic administration of minoxidil protects elastic fibers and stimulates their neosynthesis with improvement of the aorta mechanics in mice

Arterial wall elastic fibers, made of 90% elastin, are arranged into elastic lamellae which are responsible for the resilience and elastic properties of the large arteries (aorta and its proximal branches). Elastin is synthesized only in early life and adolescence mainly by the vascular smooth muscles cells (VSMC) through the cross-linking of its soluble precursor, tropoelastin. In normal aging, the elastic fibers become fragmented and the mechanical load is transferred to collagen fibers, which are 100–1000 times stiffer than elastic fibers. Minoxidil, an ATP-dependent K⁺ channel opener, has been shown to stimulate elastin expression in vitro, and in vivo in the aorta of male aged mice and young adult hypertensive rats. Here, we have studied the effect of a 3-month chronic oral treatment with minoxidil (120 mg/L in drinking water) on the abdominal aorta structure and function in adult (6-month-old) and aged (24-month-old) male and female mice. Our results show that minoxidil treatment preserves elastic lamellae integrity at both ages, which is accompanied by the formation of newly synthesized elastic fibers in aged mice. This leads to a generally decreased pulse pressure and a significant improvement of the arterial biomechanical properties in female mice, which present an increased distensibility and a decreased rigidity of the aorta. Our studies show that minoxidil treatment reversed some of the major adverse effects of arterial aging in mice and could be an interesting anti-arterial aging agent, also potentially usable for female-targeted therapies.     

Behavioural and endocrine responses of female mice to synthetic analogues of volatile compounds in male urine

The urine of intact, adult male mice elicits more investigatory sniffing from female mice than does the urine of castrated males. When either of two androgen-dependent urinary compounds, 2-sec-butyl dihydrothiazole or dehydro-exo-brevicomin are added to castrate urine, its relative attractiveness remains the same. When both compounds are added to castrate urine, however, its activity is enhanced and the castrate urine becomes as attractive to females as whole, intact male urine. Females exposed to the reconstituted ‘normal’ urine for 3 min per day, displayed more frequent oestrus cycles. The two synthetic compounds are synergistic in the context of castrate urine, producing an olfactory message that behaviourally and physiologically mimics the activity of the normal biological signal.     

Testosterone Increases Susceptibility to Amebic Liver Abscess in Mice and Mediates Inhibition of IFNγ Secretion in Natural Killer T Cells

Amebic liver abscess (ALA), a parasitic disease due to infection with the protozoan Entamoeba histolytica, occurs age and gender dependent with strong preferences for adult males. Using a mouse model for ALA with a similar male bias for the disease, we have investigated the role of female and male sexual hormones and provide evidence for a strong contribution of testosterone. Removal of testosterone by orchiectomy significantly reduced sizes of abscesses in male mice, while substitution of testosterone increased development of ALA in female mice. Activation of natural killer T (NKT) cells, which are known to be important for the control of ALA, is influenced by testosterone. Specifically activated NKT cells isolated from female mice produce more IFNγ compared to NKT cells derived from male mice. This high level production of IFNγ in female derived NKT cells was inhibited by testosterone substitution, while the IFNγ production in male derived NKT cells was increased by orchiectomy. Gender dependent differences were not a result of differences in the total number of NKT cells, but a result of a higher activation potential for the CD4⁻ NKT cell subpopulation in female mice. Taken together, we conclude that the hormone status of the host, in particular the testosterone level, determines susceptibility to ALA at least in a mouse model of the disease.     

Sex differences in susceptibility of ICR mice to oral infection with Corynebacterium kutscheri.

Sex difference in susceptibility to oral infection with Corynebacterium (C.) kutscheri was experimentally studied in ICR mice. Immature (4-week-old) and adult (14-week-old) mice were inoculated with two infecting doses of C. kutscheri, and necropsied for bacteriological and serological survey 4 weeks after the bacterial infection. No macroscopic lesions at necropsy were demonstrated, except for one adult male given 10(9) bacteria. In immature mice, C. Kutscheri isolated from the oral cavity and cecum with FNC agar, were recovered in only 40.0% of female mice but in 90.0% of male mice given 10(6) bacteria (p < 0.05), and in only 55.6% of female mice but in 80.0% male mice given 10(8) bacteria. In adult mice given 10(9) bacteria, the organism were recovered in only 45.5% of female mice but in 90.9% of male mice (p < 0.05), furthermore, the mean number of organisms in the cecum of male mice harboring the organism was significantly higher than that in females (p < 0.01). Castration caused an increase in host resistance in adult male mice. These results indicated that ICR male mice were more susceptible than females, in terms of bacterial colonization in the cecum and the oral cavity, to oral infection with C. kutscheri.     

Effect of host sex on passive immunity in mice infected with Nematospiroides dubius

Dobson C. & Owen M. E. 1978. Effect of host sex on passive immunity in mice infected with Nematospiroides dubius. International Journal for Parasitology8: 359–364. Female C₃H but not Quackenbush (Q) mice harboured fewer Nematospiroides dubius than male C₃H and Q mice. Both strains lost worms 21 days after infection. C₃H and Q mice became progressively immune to infection following 4 sequential doses of N. dubius larvae and showed a sex resistance to infection. Hypothymic nu/nu CBA Balb/c mice did not show these effects on N. dubius infection. The reciprocal transfer of male and female immune mesenteric lymph node cells (IMLNC) to syngeneic male and female recipients showed that the female environment enhanced the protective qualities of both male and female IMLNC but the male environment suppressed these effects. Gonadectomized male and female recipients of male and female IMLNC had levels of infection similar to the entire female recipients. Serum from immune female donor mice protected both male and female recipients better than immune serum from male donors, but female mice in each treatment group were better protected than male mice. Immune serum transferred greater levels of protection then IMLNC to recipient mice against N. dubius infections. These data are consistent with the conclusion that the male environment suppresses lymphocyte activity and the production of protective antibodies and additionally may depress the effectiveness of sensitized lymphocytes and antibodies in ejecting N. dubius. On the other hand the female environment does not appear to adversely affect the mobilization of the protective immune response and may enhance immune effector mechanisms in protecting mice against N. dubius infections.     

The satellite cell in male and female, developing and adult mouse muscle: distinct stem cells for growth and regeneration

Satellite cells are myogenic cells found between the basal lamina and the sarcolemma of the muscle fibre. Satellite cells are the source of new myofibres; as such, satellite cell transplantation holds promise as a treatment for muscular dystrophies. We have investigated age and sex differences between mouse satellite cells in vitro and assessed the importance of these factors as mediators of donor cell engraftment in an in vivo model of satellite cell transplantation. We found that satellite cell numbers are increased in growing compared to adult and in male compared to female adult mice. We saw no difference in the expression of the myogenic regulatory factors between male and female mice, but distinct profiles were observed according to developmental stage. We show that, in contrast to adult mice, the majority of satellite cells from two week old mice are proliferating to facilitate myofibre growth; however a small proportion of these cells are quiescent and not contributing to this growth programme. Despite observed changes in satellite cell populations, there is no difference in engraftment efficiency either between satellite cells derived from adult or pre-weaned donor mice, male or female donor cells, or between male and female host muscle environments. We suggest there exist two distinct satellite cell populations: one for muscle growth and maintenance and one for muscle regeneration.     

Behavioral despair in mice after prenatal stress

Maternal stress during pregnancy produced behavioral alterations in both sexes with regard to sexual behavior, aggressive, maternal, lateralization and depression. In the present paper, sex differences for depression in mice was studied. No sex differences between female and male mice groups were observed either in swimming-induced immobility or in the open-field test (ambulation, rearing and boluses). Prenatal stress produced: 1) an increase of immobility time in female mice for swimming-induced immobility, but not in male mice; 2) an increase of ambulation in female mice for open-field test, but not in male mice; 3) there were no significant differences in rearing and boluses between stress and control groups either for female or male mice. Prenatal stress increases the risk of depression and locomotor activity in adult female mice.     

Adult male–female social bond advertising: The primary function of coordinated singing intensity in a small ape

Adult male and female coordinated singing occur in diverse animal taxa. Adult male–female social bond advertising and strengthening have been proposed as two important functional hypotheses of coordinated singing. Here we studied these two functions in four groups of cao vit gibbon (Nomascus nasutus), a small ape that lives in polygynous family groups and adult members coordinated their sex-specific songs to produce complex duets or trios (three members sing together), using 6-year field behavioral data. In this study, we used the number of successful great call sequences per bout or per minute, and latency period from start of the adult male call to the first successful great call sequence to represent singing intensity. We used the proportion of proximity, behavioral synchronization, and grooming between adult male and female to represent bond strength. We used linear mixed-effects model to investigate the correlation between singing intensity and adult male–female social bond strength. We found a negative correlation between all three bond strength indicators and female latency period (N = 209), and a positive correlation between the number of successful great call sequences per bout (N = 253) and per minute (N = 254) and proximity. We used paired Wilcoxon signed-rank test to investigate if adult gibbons increase bond strength after singing. We found proximity (hourly level: N = 45; daily level: N = 54), behavioral synchronization (hourly level: N = 57; daily level: N = 49), and grooming (daily level: N = 34) in most of the groups did not increase significantly after singing in an hourly or daily level. Together, these results indicate that cao vit gibbon coordinated singing serves primarily in adult male–female social bond advertising and distinct singing intensity indicators advertise different information on adult male–female social bond strength.     

幼小鼠对种内几种化学信息的识别和反应

50年代以来,国际上相继开展了一些关于化学信息在小家鼠繁殖中作用的研究,并在实验室中揭示了一些反应:如集群雌鼠气味使雌鼠性周期延长的Lee-Boot效应,雌鼠气味能解除集群雌鼠对性周期的抑制、并促使它们同期发情的Whitten效应,以及陌生雄鼠气味中断妊娠的Bruce效应等等。但是,在成鼠间起作用的几种化学信息,是否能被幼鼠感受,对幼鼠的发育和性成熟是否产生影响,还是一个未知的问题。 影响小鼠发育的因素很多,除环境因子外,近来还出现了有关社群因素中外激素对小鼠性成熟影响的报道,发现雄鼠或给予雄激素的雌鼠有促进幼雌鼠性成熟的作用,范志勤发现父本气味和陌生雄鼠气味对幼雌鼠性成熟均有促进作用。但是,目前关于种内雌鼠气味、集群雌鼠气味、幼鼠气味影响性成熟的研究尚不多见。有关各种气味对性成熟效应的比较的报道亦少。本文的目的在于通过实验方法,阐明种内的几种化学信息,诸如父本、陌生雄性、雌性、集群雌性、幼雌等几种气味,对幼雌小鼠性成熟的影响,并据此了解幼鼠识别这几种信息的能力。     

Deletion of the eNOS gene has a greater impact on the pulmonary circulation of male than female mice

Nitric oxide is involved in development and postnatal adaptation of the pulmonary circulation. This study aimed to determine whether genetic deletion of nitric oxide synthase (NOS) would lead to maldevelopment of the pulmonary arteries in fetal life, compromise adaptation to extrauterine life, and be associated with a pulmonary hypertensive phenotype in adult life and if any abnormalities were detected, were they sex dependent. Morphometric analyses were made on lung tissue from male and female fetal, newborn, 14-day-old, and adult endothelial NOS-deficient (eNOS-/-) or inducible NOS-deficient (iNOS-/-) and wild-type mice. Hemodynamic studies were carried out on adult mice with deletion of either eNOS or iNOS genes. We found that in eNOS-/- mice, lung development was normal in fetal, newborn, and adult lungs. Pulmonary arterial muscularity was greater than normal in both male and female eNOS-/- during fetal life and at birth, but the abnormality persisted only in male mice. Right ventricular hypertrophy was present in 14-day-old and adult male eNOS-/- but not in female mice. Adult male eNOS-/- mice had higher mean right ventricular and systemic pressures than female eNOS-/- mice (P < 0.05). Thus deletion of the eNOS gene was associated with structural evidence of pulmonary hypertension in both sexes during fetal life, but pulmonary hypertension persisted only in the male. In neither sex did iNOS or neuronal NOS appear to compensate for the eNOS deletion. Adult iNOS-/- mice did not have structural or hemodynamic evidence of pulmonary hypertension. Possible compensatory mechanisms are discussed.     

Schistosoma mansoni: mortality, pathophysiology, and susceptibility differences in male and female mice.

In parallel studies of Schistosoma mansoni infections in male and female CBA/J mice, major sex-related differences are seen in the development of infection and disease. Upon equal subcutaneous exposures to 45 cercariae female mice present a more severe clinical course with consequent higher mortality than male mice. By 12 weeks of infection, more than 80% of female mice die, while less than 20% of infected males succumb to infection. This greater index of mortality is apparently due to the higher susceptibility of female mice to the development of adult worms. Exposed to 45 cercariae, virtually all females develop patent infections, but 8-34% of male mice do not do so. Also, the recovery rate of adult worms per cercariae from female mice is much higher than that from males, indicating that schistosomula are more successful in developing into adult worms in female mice. Additional studies indicate that this dichotomy of schistosomiasis in the sexes is not restricted to mice of the CBA/J strain, but also occurs in C57BL/6 and outbred CF1 strain mice.     

Female Mice Are More Susceptible to Nonalcoholic Fatty Liver Disease: Sex-Specific Regulation of the Hepatic AMP-Activated Protein Kinase–Plasminogen Activator Inhibitor 1 Cascade,but Not the Hepatic Endotoxin Response

As significant differences between sexes were found in the susceptibility to alcoholic liver disease in human and animal models, it was the aim of the present study to investigate whether female mice also are more susceptible to the development of non-alcoholic fatty liver disease (NAFLD). Male and female C57BL/6J mice were fed either water or 30% fructose solution ad libitum for 16 wks. Liver damage was evaluated by histological scoring. Portal endotoxin levels and markers of Kupffer cell activation and insulin resistance, plasminogen activator inhibitor 1 (PAI-1) and phosphorylated adenosine monophosphate–activated protein kinase (pAMPK ) were measured in the liver. Adiponectin mRNA expression was determined in adipose tissue. Hepatic steatosis was almost similar between male and female mice; however, inflammation was markedly more pronounced in livers of female mice. Portal endotoxin levels, hepatic levels of myeloid differentiation primary response gene (88) (MyD88) protein and of 4-hydroxynonenal protein adducts were elevated in animals with NAFLD regardless of sex. Expression of insulin receptor substrate 1 and 2 was decreased to a similar extent in livers of male and female mice with NAFLD. The less pronounced susceptibility to liver damage in male mice was associated with a superinduction of hepatic pAMPK in these mice whereas, in livers of female mice with NAFLD, PAI-1 was markedly induced. Expression of adiponectin in visceral fat was significantly lower in female mice with NAFLD but unchanged in male mice compared with respective controls. In conclusion, our data suggest that the sex-specific differences in the susceptibility to NAFLD are associated with differences in the regulation of the adiponectin–AMPK–PAI-1 signaling cascade.     

Sex difference in thermal preference of adult mice does not depend on presence of the gonads

Background

The thermoneutral zone (TNZ) is a species-specific range of ambient temperature (T _a), at which mammals can maintain a constant body temperature with the lowest metabolic rate. The TNZ for an adult mouse is between 26 and 34 °C. Interestingly, female mice prefer a higher T _a than male mice although the underlying mechanism for this sex difference is unknown. Here, we tested whether gonadal hormones are dominant factors controlling temperature preference in male and female mice.

Methods

We performed a temperature preference test in which 10-week-old gonadectomized and sham-operated male and female C57BL/6J mice were allowed to choose to reside at the thermoneutral cage of 29 °C or an experimental cage of 26, 29, or 32 °C.

Results

All mice preferred a T _a higher than 26 °C, especially in the inactive phase. Choosing between 29 and 32 °C, female mice resided more at 32 °C while male mice had no preference between the temperatures. Hence, the preferred T _a for female mice was significantly higher (0.9?±?0.2 °C) than that for male mice. However, gonadectomy did not influence the T _a preference.

Conclusions

Female mice prefer a warmer environment than male mice, a difference not affected by gonadectomy. This suggests that thermal-sensing mechanisms may be influenced by sex-specific pathways other than gonadal factors or that the thermoregulatory set point has already been determined prior to puberty.

     

Female courtship summation in Drosophila melanogaster

To examine the concept of female courtship summation in Drosophila melanogaster, two experiments previously reported in the literature, the first involving repeated matings of females and the second progressive removal of the males' wings, were repeated. The present results do not convincingly support the concept of female summation of stimuli provided by the males' courtship. The results of the first experiment also refute the idea that low male courtship intensity leads to long courtships. These results also fail to support an earlier suggestion that females summate the sine rather than pulse song component of the males' wing vibration. Instead, the variation in courtship duration appeared to result from the inverse hyperbolic relationship between the male latency to courtship and the subsequent courtship duration. Thus short male latencies led to longer courtship durations. This is interpreted as resulting from a female latency period during which the female is too agitated to receive the male's courtship, and after which she mates upon recognizing the male as conspecific. In addition, very long courtships largely resulted from additional agitation of the female by the male's courtship. Long courtships therefore appear to be an artifact of the experimental situation and the established concept of female courtship summation, which is supposed to explain them, is unnecessary. The implications of this conclusion are discussed.     

The Maestro (Mro) Gene Is Dispensable for Normal Sexual Development and Fertility in Mice

The mammalian gonad arises as a bipotential primordium from which a testis or ovary develops depending on the chromosomal sex of the individual. We have previously used DNA microarrays to screen for novel genes controlling the developmental fate of the indifferent embryonic mouse gonad. Maestro (Mro), which encodes a HEAT-repeat protein, was originally identified as a gene exhibiting sexually dimorphic expression during mouse gonad development. Wholemount in situ hybridisation analysis revealed Mro to be expressed in the embryonic male gonad from approximately 11.5 days post coitum, prior to overt sexual differentiation. No significant expression was detected in female gonads at the same developmental stage. In order to address its physiological function, we have generated mice lacking Maestro using gene targeting. Male and female mice homozygous for a Mro null allele are viable and fertile. We examined gonad development in homozygous male embryos in detail and observed no differences when compared to wild-type controls. Immunohistochemical analysis of homozygous mutant testes of adult mice revealed no overt abnormalities. Expression profiling using DNA microarrays also indicated no significant differences between homozygote embryonic male gonads and controls. We conclude that Maestro is dispensable for normal male sexual development and fertility in laboratory mice; however, the Mro locus itself does have utility as a site for insertion of transgenes for future studies in the fields of sexual development and Sertoli cell function.     

鳄蜥对熟悉和陌生个体气味的辨别

个体辨别对于减少同种争斗以及配偶选择具有重要意义。我们用棉棒粘取鳄蜥(Shinisaurus crocodilurus)尿液作为气味源,以香水作为对照,测定鳄蜥对熟悉个体气味、陌生个体气味以及香水的舔舌次数和舔舌潜伏期,来探讨鳄蜥通过化学信息辨别熟悉和陌生个体的能力。结果显示,不论是雌性还是雄性,对不同个体尿液的舔舌次数均显著高于对香水的,舔舌潜伏期显著短于香水的;尽管雄性对陌生同性个体气味与熟悉同性个体气味的舔舌次数无显著差异,但对前者的舔舌潜伏期显著短于后者;雄性对陌生雌性气味的舔舌次数显著多于熟悉雌性气味的,对前者的舔舌潜伏期显著短于后者;雌性对陌生雄性气味的舔舌潜伏期显著短于对熟悉雄性气味的;雄鳄蜥对陌生雌性气味的舔舌次数显著多于雌鳄蜥对陌生雄性的。结果表明,鳄蜥能辨别同种个体的化学信息,并能通过化学信息来辨别熟悉和陌生个体,推测鳄蜥的这种辨别能力对其领域分配以及繁殖交配有重要作用。     

Sex-specific phenotypes of hyperthyroidism and hypothyroidism in aged mice

Background

Sex and age play a role in the prevalence of thyroid dysfunction (TD), but their interrelationship for manifestation of hyper- and hypothyroidism is still not well understood. Using a murine model, we asked whether sex impacts the phenotypes of hyper- and hypothyroidism at two life stages.

Methods

Hyper- and hypothyroidism were induced by i.p. T4 or MMI/ClO₄-/LoI treatment over 7 weeks in 12- and 20-months-old female and male C57BL/6N mice. Control animals underwent PBS treatment (n?=?7–11 animals/sex/treatment). Animals were investigated for impact of sex on body weight, food and water intake, body temperature, heart rate, behaviour (locomotor activity, motor coordination and strength) and serum thyroid hormone (TH) status.

Results

Distinct sex impact was found in eu- and hyperthyroid mice, while phenotypic traits of hypothyroidism were similar in male and female mice. No sex difference was found in TH status of euthyroid mice; however, T4 treatment resulted in twofold higher TT4, FT4 and FT3 serum concentrations in adult and old females compared to male animals. Hyperthyroid females consistently showed higher locomotor activity and better coordination but more impairment of muscle function by TH excess at adult age. Importantly and in contrast to male mice, adult and old hyperthyroid female mice showed increased body weight. Higher body temperature in female mice was confirmed in all age groups. No sex impact was found on heart rate irrespective of TH status in adult and old mice.

Conclusions

By comparison of male and female mice with TD at two life stages, we found that sex modulates TH action in an organ- and function-specific manner. Sex differences were more pronounced under hyperthyroid conditions. Importantly, sex-specific differences in features of TD in adult and old mice were not conclusively explained by serum TH status in mice.