Methamphetamine-induced conditioned place preference is facilitated by estradiol pretreatment in female mice

Ovarian hormones were well documented to modulate the dopamine release in the central dopaminergic systems. The dopamine-releasing effects in the nucleus accumbens, a major target of the mesolimbicortical dopaminergic system, were closely associated with the reinforcing effects of two psychomotor stimulants, cocaine and methamphetamine. This study aimed to examine the sex differences in the cocaine- and methamphetamine-reinforcing behavior, conditioned place preference. In addition, the modulating effects of estradiol and progesterone on methamphetamine-induced conditioned place preference were investigated in both sexes of adult gonadectomized mice. There was no sex difference in the sensitivity to the cocaine (5 mg/kg)-induced conditioned place preference. However, female mice exhibited a more potent methamphetamine (1 mg/kg)-induced conditioned place preference than did male mice. Moreover, pretreatment with estradiol for two consecutive days before the beginning of the conditioning and throughout the four daily conditionings (0.47 microg/day for totally six days) effectively facilitated methamphetamine-induced conditioned place preference in gonadectomized female mice, but not in gonadectomized male mice. Progesterone, under a similar treatment regimen (0.47 microg/day for six consecutive days), did not alter the methamphetamine-induced conditioned place preference in either sex of gonadectomized mice. Taken together, we conclude that the facilitating effects of estradiol on methamphetamine-induced conditioned place preference could be sex-dependent with an eminent sensitivity associated with the adult female mice.     

The effect of hormones on experimental moniliasis in mice

Summary By inoculating testosterone or estradiol alone and in combination with cortisone and somatotrophic hormone into male and female mice infected with moniliasis, it was shown that these sex hormones play a major role in modifying the course of the infection in these animals. The use of testosterone indicated that it had a marked synergistic activity with cortisone in enhancing the severity of the infection for both sexes. In addition, a mixture of testosterone and cortisone inoculated into normal mice at dosage levels which displayed no toxic effect when either agent was used alone, displayed a marked toxicity for male animals.These data also support the contention that the sex of the animal plays a major role in governing the response of normal or infected animals treated with cortisone and/or somatotrophic hormones.The possible implication of these data clinically is discussed.This paper is part of a study supported by Contract No. NONR 717(00) between the Office of Naval Research, Department of the Navy, and the Creighton University.A preliminary report of this work has been presented (Scherr, 1954a).     

Protection of mice against fission neutron irradiation by WR-2721 or WR-151327

Two phosphorothioate compounds, WR-2721 and WR-151327, were examined for their radioprotective efficacies against the effects of fission neutron irradiation in male and female mice. Within sex groups no significant difference in lethality at 30 or 100 days postirradiation was found between WR-2721 or WR-151327 pretreatment. The dose modification factors (DMFs) for male mice treated with either compound were 1.29 (LD50/30) and 1.24 (LD50/100), and those for drug-treated female mice were 1.21 (LD50/30) and 1.19 (LD50/100). Both WR-2721 and WR-151327 were found to be equally radioprotective when compared using DMFs as the end point. WR-151327 (500 mg/kg, ip) was found to be significantly more toxic to both male and female B6D2F1 mice than equimolar amounts of WR-2721. Small but significant sex differences in radioprotection were found: the DMFs for female mice pretreated with either compound were lower than those for similarly treated male mice; the incidence of mortality 31-100 days postexposure in male mice pretreated with WR-151327 was greater than for female mice. In addition, sex differences were noted in drug toxicity. Toxic death in female mice given WR-151327 (500 mg/kg, ip) is 2.6 times more probable than in males.     

Influence of testosterone on hydronephrosis in the inbred mouse strain DDD

Hereditary hydronephrosis was detected in all of the male mice of DDD inbred strain maintained at the National Institute of Animal Health Japan, but in only a few of the females. From the standpoint that male hormones are related to the development of hydronephrosis in this strain, the incidence and severity of the disease were investigated in gonadectomized mice treated with testosterone. In the males, the incidence of hydronephrosis was 50% (7/14) in the control (gonadectomized) group, and 73.3% (11/15), 100% (13/13) and 100% (12/12) in the 0.1 mg, 3.3 mg and 10 mg treatment groups respectively. The same tendency was observed in the female animals, though the incidence in each group was not so high. In both sexes the degree of severity increased in proportion to the dose of testosterone administrated. Blood testosterone levels were higher in intact DDD mice than in C57BL/6 mice, which had normal kidneys in both sexes. These results suggest that male hormones play a significant role in the development of hydronephrosis.     

Sex differences in ferric nitrilotriacetate-induced lipid peroxidation and nephrotoxicity in mice

Since male A/J mice are much more susceptible to both acute and subacute nephrotoxicity and the carcinogenic effect of ferric nitrilotriacetate than female mice, sex differences in the lipid peroxidation level after ferric nitrilotriacetate use were examined. The effects of orchiectomy and testosterone were also investigated. Male and female A/J mice were given a single intraperitoneal injection of ferric nitrilotriacetate (3 mg of iron/kg of body weight) and then thiobarbituric acid reactivity was determined in the liver and the kidney. Only male mice showed high thiobarbituric acid reactivity after 30 min, with the kidney showing higher activity than the liver. Castrated male mice showed a reduction in thiobarbituric acid reactivity, whereas testosterone-pretreated castrated male or testosterone-pretreated female mice showed increased thiobarbituric acid reactivity. In addition, daily intraperitoneal injections of ferric nitrilotriacetate resulted in the death of all normal male mice within 6 days, whereas all female and castrated male mice survived 3 months of treatment. Thus, male and female mice showed differences in ferric nitrilotriacetate-induced toxicity as reflected in the degree of lipid peroxidation and mortality.     

Sex chromosome complement affects nociception in tests of acute and chronic exposure to morphine in mice

We tested the role of sex chromosome complement and gonadal hormones in sex differences in several different paradigms measuring nociception and opioid analgesia using "four core genotypes" C57BL/6J mice. The genotypes include XX and XY gonadal males, and XX and XY gonadal females. Adult mice were gonadectomized and tested 3-4 weeks later, so that differences between sexes (mice with testes vs. ovaries) were attributable mainly to organizational effects of gonadal hormones, whereas differences between XX and XY mice were attributable to their complement of sex chromosomes. In Experiment 1 (hotplate test of acute morphine analgesia), XX mice of both gonadal sexes had significantly shorter hotplate baseline latencies prior to morphine than XY mice. In Experiment 2 (test of development of tolerance to morphine), mice were injected twice daily with 10 mg/kg morphine or saline for 6 days. Saline or the competitive NMDA antagonist CPP (3-(2-carboxypiperazin-4yl) propyl-1-phosphonic acid) (10 mg/kg) was co-injected. On day 7, mice were tested for hotplate latencies before and after administration of a challenge dose of morphine (10 mg/kg). XX mice showed shorter hotplate latencies than XY mice at baseline, and the XX-XY difference was greater following morphine. In Experiment 3, mice were injected with morphine (10 mg/kg) or saline, 15 min before intraplantar injection of formalin (5%/25 microl). XX mice licked their hindpaw more than XY mice within 5 min of formalin injection. The results indicate that X- or Y-linked genes have direct effects, not mediated by gonadal secretions, on sex differences in two different types of acute nociception.     

A Comparison of Spontaneous and Odor-induced Chin Marking in Male and Female Domestic Rabbits (Oryctolagus cuniculus domestica)

Chin marking by the European rabbit (Oryctolagus cuniculus) is one of the classic but still little understood examples of mammalian chemical communication. To investigate whether the sexes differ in performance of this behavior, we compared the frequency of spontaneous chinning and chinning in response to the chin marks of conspecifics in 20 intact male and 20 intact female chinchilla-breed rabbits, and in five gonadectomized animals of each sex. Contrary to the expectation of greater chinning activity in males, no significant sex differences were found. Frequencies of spontaneous chinning were similar in the two sexes, large and stable individual differences were observed in both, chinning increased in both when marks from unfamiliar conspecifics were present, and both directed chin marks to objects marked by conspecifics more than to unmarked objects. Individual chinning frequencies correlated positively with urination but not defecation in both sexes, and spontaneous and odor-induced chinning were significantly reduced both in castrated and ovariectomized animals. The findings suggest that chinning is an equally significant part of the communication system of male and female rabbits and that its expression may be regulated by similar olfactory, hormonal, and social mechanisms.     

Estradiol is responsible for reduced renal prostaglandin dehydrogenase activity in female rats

The contribution of sex steroids to sex-related differences in renal prostaglandin dehydrogenase activity and urinary prostaglandin excretion was examined in 7-8-week-old male and female rats subjected to sham-operation or gonadectomy at 3 weeks of age. Rats were injected subcutaneously twice over a 6-day interval with vehicle (peanut oil, 0.5 mg/kg) or with depot forms of testosterone (10 mg/kg), estradiol (0.1 mg/kg), progesterone (5 mg/kg), or with estradiol and progesterone combined (0.1 and 5 mg/kg). After the second injection, 24-h urine samples were collected for prostaglandin measurement by radioimmunoassay; the rats were killed, and renal and pulmonary prostaglandin dehydrogenase activities were determined by radiochemical assay. Renal prostaglandin dehydrogenase activity was 10-times higher in intact male rats than in intact females. Gonadectomy increased renal prostaglandin dehydrogenase activity 4-fold in females, but had no effect in males; estradiol, alone or combined with progesterone, markedly suppressed renal prostaglandin dehydrogenase activity in both sexes, while testosterone or progesterone alone had no effect. Pulmonary prostaglandin dehydrogenase did not differ between the sexes and was unaffected by gonadectomy or sex-steroid treatment. Intact female sham-operated rats excreted 70-100% more prostaglandin E2, prostaglandin F2 alpha, and 6-keto-prostaglandin F1 alpha in urine than did males; gonadectomy abolished the difference in urinary prostaglandin E2 excretion. Estradiol decreased urinary prostaglandin E2 in females but not in males; treatment with other sex steroids did not alter urinary prostaglandin excretion.     

Differential effects of 3,4,5,3',4',5' -hexachlorobiphenyl (hcb) on interrenal steroidogenesis in male and female rainbow trout Oncorhynchus mykiss

1. The conversion of progesterone to 17α-hydroxyprogesterone (17α-OHP), 11-deoxycortisol (11-DOCR) and deoxycorticosterone (DOC) was significantly higher in female rainbow trout than in male trout; in contrast, the interrenal production of cortisol (CR) plus cortisone (CN) was higher in males than in females.2. Following treatment with 1 mg/kg of HCB, the interrenal conversion of progesterone to 17α-OHP and 11-DOCR was significantly increased in male and female trout but at 20 mg/kg of HCB, the production of these metabolites was increased in males and decreased in females; CR + CN production was unchanged after HCB treatment in both sexes.     

Changes in the renin-angiotensin-aldosterone system in rats of both sexes submitted to chronic hypobaric hypoxia

The effect of moderate chronic hypobaric hypoxia (CHH) on the renin-angiotensin-aldosterone system has been analysed in male and female intact and castrated rats. The experimental animals were submitted to a simulated altitude of 4,400 m during ten weeks. Half of the experimental and half of the control animals were castrated at three weeks of age. Arterial pressure (AP) was measured once a week during the whole experimental period. Blood samples were obtained by decapitation at the end of the study. Red cell volume, plasma renin activity (PRA), plasma angiotensinogen (Ao) and aldosterone concentration (ALDO) were determined in the blood samples. Results have shown that the female animals subjected to CHH had lower levels of AP than the control female rats during all the studied periods whereas the AP of male hypoxic rats was only transiently diminished. All these changes were abolished by castration. PRA was not altered in either sex. The enzymatic complex was higher in male than in female control animals and decreased after castration in both hypoxic and control male rats. Ao was decreased by CHH in both sexes of intact rats and in female castrated animals. The renin substrate was higher in male than in female intact rats and decreased after castration in male animals. ALDO was increased after CHH only in male rats. Control female rats have higher levels of ALDO than male animals. Changes in the renin-angiotensin-aldosterone system related to CHH and also significant differences between sexes suggest that adrenal and gonadal corticosteroids may be involved in the main alterations presently observed.     

Testosterone and estrogen differently effect Th1 and Th2 cytokine release following trauma-haemorrhage.

The object of the study was to determine whether male and female sex steroids produce divergent effects on Th1 and Th2 cytokine release following trauma-haemorrhage. Recent studies indicate that androgens are responsible for the depressed splenocyte Th1 cytokine release in males following trauma-haemorrhage. In contrast, female mice maintain their Th1 cytokine release capacity following trauma-haemorrhage. Nonetheless, the effect of male and female sex steroids on Th1 and Th2 cytokine release following trauma-haemorrhage remains unknown. Male C3H/HeN mice were castrated and treated with pellets containing either vehicle, 5alpha-dihydrotestosterone (DHT), 17beta-estradiol (estradiol), or a combination of both steroid hormones, for 14 days prior to soft-tissue trauma (i.e. laparotomy) and haemorrhagic shock (35+/-5 mmHg for 90 min followed by adequate fluid resuscitation) or sham operation. Untreated male and female mice, as well as DHT treated female mice, served as control groups. Twenty-four hours later the animals were sacrificed, plasma obtained and splenocytes harvested. Plasma DHT and estradiol levels in treated animals were comparable with intact male and female mice, respectively. A significant depression of splenocyte Th1 cytokines, i.e. IL-2, IFN-gamma, was observed in DHT treated castrated animals, DHT treated females, and untreated males following trauma-haemorrhage, as opposed to maintained Th1 cytokine release in estradiol treated and estradiol/DHT treated castrated animals and females. The release of the anti-inflammatory cytokine IL-10 was markedly increased in DHT treated mice and males subjected to trauma-haemorrhage compared to shams, but decreased in estrogen treated mice and females under such conditions. These results suggest that male and female sex steroids differentially affect the release of Th1 and Th2 cytokines following trauma-haemorrhage and should be further studied for their potential to modulate splenocyte function in trauma victims.     

Effects of long term low dose acrylamide exposure on rat bone marrow polychromatic erythrocytes

Abstract

I investigated whether long term low dose exposure to acrylamide increased micronucleus frequency in rat bone marrow polychromatic erythrocytes (PCEs). Twenty-five male and 25 female Wistar rats were used. Animals of each sex were segregated into two treatment groups and one control group. Each treatment group consisted of ten animals and each control group consisted of five animals. Acrylamide, 2 or 5 mg/kg/day, was administered to the treatment groups in their drinking water for 90 days. Twenty-four hours after the last treatment, bone marrow samples were obtained and analyzed for the frequency of micronucleated polychromatic erythrocytes (MNPCEs). The cytotoxic effect of acrylamide on bone marrow also was tested by assessing the polychromatic erythrocyte/normochromatic erythrocyte (PCE/NCE) ratio. Both doses of acrylamide significantly increased the frequency of MNPCEs in both male and female rats. Acrylamide also decreased the PCE/NCE ratio in both sexes compared to the control group. My study showed that chronic low dose exposure to acrylamide increased the formation of micronuclei in PCEs of male and female rat bone marrow.     

Transient sex-related changes in the mice hypothalamo-pituitary-adrenal (HPA) axis during the acute phase of the inflammatory process

The potential role of endogenous sex hormones in regulating hypothalamo-pituitary-adrenal (HPA) axis function was investigated after a single injection of endotoxin in adult (8 week old) BALB/c mice of both sexes. The effect of LPS on plasma ACTH, corticosterone (B), testosterone and oestradiol (E) levels and on anterior pituitary (AP) ACTH and adrenal B contents at different times after treatment was studied. The results indicate that: (a) basal B but not ACTH plasma levels were significantly higher in female than in male mice; (b) LPS significantly increased both ACTH and B plasma levels over the baseline 2 h after injection, both hormone levels being higher in female than in male mice; (c) although plasma ACTH concentrations recovered the basal value at 72 h after LPS in animals of both sexes, plasma B levels returned to the baseline only at 120 h after treatment; (d) E plasma levels significantly increased 2 h after LPS and returned to the baseline at 72 h post-treatment, in both sexes; (e) at 2 h after LPS, testosterone plasma levels significantly decreased in male mice and increased in female mice, recovering the baseline level at 120 and 72 h after LPS, respectively; (f) AP ACTH content was similar in both sexes in basal condition and it was significantly diminished 72 h post-treatment without sex difference; whereas AP ACTH returned to basal content 120 h after LPS in males, it remained significantly decreased in females; (g) basal adrenal B content was higher in female than in male mice, and it significantly increased in both sexes 2 h post-LPS, maintaining this sex difference. Whereas adrenal B returned to basal content 72 h after treatment in male mice, it remained significantly enhanced up to 120 h post-LPS in female animals. The data demonstrate the existence of a clear sexual dimorphism in basal condition and during the acute phase response as well as in the recovery of the HPA axis function shortly after infection.     

Sex differences in lifespan extension with acarbose and 17‐α estradiol: gonadal hormones underlie male‐specific improvements in glucose tolerance and mTORC2 signaling

Interventions that extend lifespan in mice can show substantial sexual dimorphism. Here, we show that male‐specific lifespan extension with two pharmacological treatments, acarbose (ACA) and 17‐α estradiol (17aE2), is associated, in males only, with increased insulin sensitivity and improved glucose tolerance. Females, which show either smaller (ACA) or no lifespan extension (17aE2), do not derive these metabolic benefits from drug treatment. We find that these male‐specific metabolic improvements are associated with enhanced hepatic mTORC2 signaling, increased Akt activity, and phosphorylation of FOXO1a – changes that might promote metabolic health and survival in males. By manipulating sex hormone levels through gonadectomy, we show that sex‐specific changes in these metabolic pathways are modulated, in opposite directions, by both male and female gonadal hormones: Castrated males show fewer metabolic responses to drug treatment than intact males, and only those that are also observed in intact females, while ovariectomized females show some responses similar to those seen in intact males. Our results demonstrate that sex‐specific metabolic benefits occur concordantly with sexual dimorphism in lifespan extension. These sex‐specific effects can be influenced by the presence of both male and female gonadal hormones, suggesting that gonadally derived hormones from both sexes may contribute to sexual dimorphism in responses to interventions that extend mouse lifespan.     

4-chloro-o-phenylenediamine induces a dose-related increase in G:C > T:A transversions and one major DNA adduct in the liver of Big Blue mice after 26 weeks in feed treatment

The monocyclic aromatic amine 4-chloro-o-phenylenediamine (4-C-o-PDA), a known mutagen and mouse hepatocarcinogen, was tested for its in vivo mutagenic potential in the Big Blue transgenic mouse assay system. Genomic DNA was isolated from liver tissue of control and treated animals and lacI mutants were recovered. In an initial 2-week study 4-C-o-PDA was administered daily per os to groups of male and female C57BL/6 Big Blue mice at doses of 0 and 200 mg/kg for 2 weeks (on working days) followed by a treatment free expression time of 10 days. Only a weak increase in the mutant frequencies in females was observed. In a 26-week study, where 4-C-o-PDA was given to groups of male and female Big Blue mice in feed at dietary concentrations of 0, 5,000 and 10,000 ppm, 4-C-o-PDA was found to induce a pronounced dose-dependent increase in mutant frequencies in either sex. In the present work, we analyzed the mutation spectrum by automated DNA sequencing of lacI mutants from both studies. Following the 2-week administration of 4-C-oT:A transversions in both sexes. In addition, upon 26-week treatment with 4-C-o-PDA, one major DNA adduct was detected by 33P postlabelling and subsequent multidimensional thin layer chromatography. It is concluded that 4-C-oT:A transversions after 26 weeks in feed treatment. This result indicates that the sensitivity of the Big Blue transgenic assay system, in detecting a unique chemically induced mutation spectrum, is dependent on experimental parameters, such as treatment time. The data suggest that the formation of one major DNA adduct upon 4-C-o-PDA treatment may be critical for its mutagenicity.     

Nippostrongylus brasiliensis: effects of testosterone on reproduction and establishment

Gonadectomy of the host reduced the establishment of Nippostrongylus brasiliensis in male mice, but elevated the recovery of worms from female hosts. Similarly, production of eggs by individual females of N. brasiliensis decreased and increased in gonadectomized male and female animals, respectively. Implantation of testosterone-filled capsules caused a dosage-dependent release of eggs by helminths in gonadectomized hosts of both sexes. Maximal production of eggs by nematodes was found when plasma testosterone in the host exceeded 20 ng/ml. Treatment of gonadectomized mice of both sexes with testosterone implants gave recoveries of worms that were similar to the number of helminths in intact male mice. Ligation of the bile duct of male mice that were implanted with testosterone reduced both establishment and reproduction of N. brasiliensis.     

Stimulation of pituitary corticotrophs in the rat--ultrastructural studies

The ultrastructural changes occurring in the corticotrophs of adult male and female Sprague-Dawley rats at 2 and 6 weeks after bilateral adrenalectomy were assessed on both a qualitative and quantitative basis. Qualitative changes were similar to those previously described but at both time points, female rats showed more marked changes than males. Corticotroph hypertrophy reached a plateau in male animals between 2 and 6 weeks, but continued to increase in females. There was an increase in mean granule diameter in both sexes at 2 weeks after adrenalectomy. The changes induced by the daily administration of CRF for 2 weeks by intraperitoneal injection were also examined in male rats. CRF induced corticotroph hypertrophy at both 25 micrograms/Kg and 50 micrograms/Kg body weight and increased the granule content. The addition of vasopressin (VP) to the higher dose of CRF induced a further increase in cell area and reduction in granule content. Low dose CRF was associated with an increase in mean granule diameter, whereas a decrease was seen after high dose.     

Influence of age and sex on hepatotoxic and hypothermic effects of estrogole in mice

Some physiological effects of estragole under a single intraperitoneal injection in oil solution were studied in GR mice; elevation of blood aminotransferases activity, body temperature and animals lethality were registered. At a dose of 600 mg/kg, estragole killed 100% sucklings of both sexes and 90% adult females but no any adult male. The males aquire resistance to estragole at the time of maturation. Exogenous testosterone administered at the dose of 50 mg/kg 4-2 days earlier increases the resistance of female mice to estragole up to its level in males. However, neonatally androgenized females are as sensitive to the toxic action of estragole as the males. At the dose of 900 mg/kg, estragole defeats adult males as well: significant elevation of aminotransferase activities in their blood is indicative of this. In this case, the enzyme activity reaches its peak after 2-3 days, not at the 1st day as in the case of carbon tetrachloride administration. We have discovered a strong hypothermic effect of estragole which appears to be unrelated to its hepatotoxicity and testosteron level.