Evidence for the involvement of ERbeta and RGS9-2 in 17-beta estradiol enhancement of amphetamine-induced place preference behavior.
ABSTRACT: Estrogen enhances dopamine-mediated behaviors, which make women and female rats more sensitive to the effects of the psychostimulant drugs, cocaine and amphetamine. How cocaine and amphetamine elicit more robust behavioral responses in females remains unclear, but studies have shown that the Regulator of G-protein Signaling 9-2 (RGS9-2) protein is an important modulator of the behavioral responses to these drugs. Previously, we reported that 17-beta estradiol reduced RGS9-2 mRNA expression in the shell of the nucleus accumbens, but not the core. The present studies were designed to further evaluate the involvement of RGS9-2 in estradiol enhancement of amphetamine-induced place preference behavior and to examine which estrogen receptor subtype mediates the effect of estradiol. Female Sprague-Dawley rats were ovariectomized and treated for 14 days with an inert vehicle or 17-beta estradiol (by Silastic implant or injection [80 microg/kg]). 17-beta-Estradiol-treated female rats had enhanced amphetamine-induced conditioned place preference behavior compared to vehicle-treated, ovariectomized female rats. In situ hybridization histochemistry and Western blotting identified an inverse relationship between RGS9-2 protein expression in the nucleus accumbens shell and the hormonal enhancement of amphetamine-induced place preference behavior. A similar relationship was not found between place preference behavior and RGS9-2 expression in the accumbens core. Moreover, treatment of ovariectomized female rats with the selective estrogen receptor-beta agonist, diarylpropionitrile (1 mg/kg), for 2 weeks also facilitated amphetamine-induced place preference behavior and selectively reduced nucleus accumbens shell RGS9-2 protein expression. These data provide insight into a potential mechanism by which estrogen and/or sex modulate mesoaccumbal dopamine receptor signaling and possibly, addictive behaviors.
Project description:Background:Females are more vulnerable to developing cocaine addiction compared with males, a phenomenon that may be regulated by the steroid hormone 17?-estradiol. 17?-Estradiol enhances cocaine reward as measured by the conditioned place preference test. It is currently not known which estrogen receptor is involved or the neuroanatomical locations in which estrogen receptors act to enhance cocaine responses. The purpose of this study was to determine if the estrogen receptors ER? and ER? regulate cocaine conditioned place preference in mice and whether they act in the nucleus accumbens, a brain region critically involved in the development of cocaine abuse. Methods:Ovariectomized mice were treated with 17?-estradiol or agonists selective for ER? or ER? and tested for cocaine conditioned place preference and for c-fos expression in the nucleus accumbens. Female mice with intact ovaries were also tested for cocaine conditioned place preference after RNA interference-mediated knockdown of ER? or ER? in the nucleus accumbens. Results:We found that mice treated with 17?-estradiol or an ER? agonist exhibited increased cocaine conditioned place preference, while knockdown of ER?, but not ER?, in the nucleus accumbens of females with intact ovaries abrogated cocaine conditioned place preference. Acute treatment with 17?-estradiol or an ER? agonist induced expression of the immediate-early gene c-fos in the nucleus accumbens, whereas the ER? agonist did not. Conclusions:These data indicate that ER? in the nucleus accumbens regulates the development of cocaine conditioned place preference in female mice. 17?-Estradiol may activate neurons in the nucleus accumbens via ER?. We speculate that this might increase the saliency of cocaine cues that predict drug reward.
Project description:<h4>Background</h4>Temporomandibular disorders (TMDs) have the highest prevalence in women of reproductive age. The role of estrogen in TMDs and especially in TMDs related pain is not fully elucidated. Voltage-gated sodium channel 1.7 (Nav1.7) plays a prominent role in pain perception and Nav1.7 in trigeminal ganglion (TG) is involved in the hyperalgesia of inflamed Temporomandibular joint (TMJ). Whether estrogen could upregulate trigeminal ganglionic Nav1.7 expression to enhance hyperalgesia of inflamed TMJ remains to be explored.<h4>Methods</h4>Estrous cycle and plasma levels of 17?-estradiol in female rats were evaluated with vaginal smear and enzyme linked immunosorbent assay, respectively. Female rats were ovariectomized and treated with 17?-estradiol at 0 ?g, 20 ?g and 80 ?g, respectively, for 10 days. TMJ inflammation was induced using complete Freund's adjuvant. Head withdrawal thresholds and food intake were measured to evaluate the TMJ nociceptive responses. The expression of Nav1.7 in TG was examined using real-time PCR and western blot. The activity of Nav1.7 promoter was examined using luciferase reporter assay. The locations of estrogen receptors (ER? and ER?), the G protein coupled estrogen receptor (GPR30), and Nav1.7 in TG were examined using immunohistofluorescence.<h4>Results</h4>Upregulation of Nav1.7 in TG and decrease in head withdrawal threshold were observed with the highest plasma 17?-estradiol in the proestrus of female rats. Ovariectomized rats treated with 80 ?g 17?-estradiol showed upregulation of Nav1.7 in TG and decrease in head withdrawal threshold as compared with that of the control or ovariectomized rats treated with 0 ?g or 20 ?g. Moreover, 17?-estradiol dose-dependently potentiated TMJ inflammation-induced upregulation of Nav1.7 in TG and also enhanced TMJ inflammation-induced decrease of head withdrawal threshold in ovariectomized rats. In addition, the estrogen receptor antagonist, ICI 182,780, partially blocked the 17?-estradiol effect on Nav1.7 expression and head withdrawal threshold in ovariectomized rats. ER? and ER?, but not GPR30, were mostly co-localized with Nav1.7 in neurons in TG. In the nerve growth factor-induced and ER?-transfected PC12 cells, 17?-estradiol dose-dependently enhanced Nav1.7 promoter activity, whereas mutations of the estrogen response element at -1269/-1282 and -1214/-1227 in the promoter completely abolished its effect on the promoter activity.<h4>Conclusion</h4>Estradiol could upregulate trigeminal ganglionic Nav1.7 expression to contribute to hyperalgesia of inflamed TMJ.
Project description:The acute effects of marijuana consumption on brain physiology and behaviour are well documented, but the long-term effects of its chronic use are less well known. Chronic marijuana use during adolescence is of increased interest, given that the majority of individuals first use marijuana during this developmental stage , and adolescent marijuana use is thought to increase the susceptibility to abusing other drugs when exposed later in life. It is possible that marijuana use during critical periods in adolescence could lead to increased sensitivity to other drugs of abuse later on. To test this, we chronically administered ? 9-tetrahydrocannabinol (THC) to male and female Long-Evans (LER) and Wistar (WR) rats directly after puberty onset. Rats matured to postnatal day 90 before being exposed to a conditioned place preference task (CPP). A subthreshold dose of d-amphetamine, found not to induce place preference in drug naïve rats, was used as the unconditioned stimulus. The effect of d-amphetamine on neural activity was inferred by quantifying cfos expression in the nucleus accumbens and dorsal hippocampus following CPP training. Chronic exposure to THC post-puberty had no potentiating effect on a subthreshold dose of d-amphetamine to induce CPP. No differences in cfos expression were observed. These results show that chronic exposure to THC during puberty did not increase sensitivity to a sub-threshold dose of d-amphetamine in adult LER and WR rats. This supports the concept that THC may not sensitize the response to all drugs of abuse.
Project description:Genistein is an active soy isoflavone with anticancer activities, but it is unknown why it has a higher oral bioavailability in female than in male rats. Our study determined the effects of estrus cycle on genistein's oral bioavailability. Female rats with various levels of estrogen were orally administered with genistein or used in a four-site rat intestinal perfusion experiment. Rats in "proestrus" group (with elevated estrogen) had significantly reduced (57% decrease, p < 0.05) oral bioavailability of total genistein (aglycone + conjugates) than those in "metoestrus" group (with basal level of estrogen). Female ovariectomized rats, due to lack of estrogen, showed oral bioavailability of total genistein similar to the "metoestrus" group but higher (155% increase, p < 0.05) than the "proestrus" group. On the basis of intestinal perfusion studies, the increased bioavailability was partially attributed to the higher (>100% increase, p < 0.05) hepatic disposition via glucuronidation and possibly more efficient enterohepatic recycling of genistein in the "metoestrus" group. Furthermore, chronic exogenous supplementation of estradiol in ovariectomized rats significantly reduced (77%, p < 0.05) the oral bioavailability of total genistein, mostly via increased sulfation (>10-fold) in liver, to a level comparable to those in the "proestrus" group. In conclusion, the oral bioavailability of total genistein was inversely proportional to elevated estrogen levels in female rats, which is partially mediated through the regulation of hepatic enzymes responsible disposition of genistein.
Project description:The integration of metabolism and reproduction involves complex interactions of hypothalamic neuropeptides with metabolic hormones, fuels, and sex steroids. Of these, estrogen influences food intake, body weight, and the accumulation and distribution of adipose tissue. In this study, the effects of estrogen on food intake, serum leptin levels, and leptin mRNA expression were evaluated in ovariectomized rats. Seven-week-old female Wistar-Imamichi rats were ovariectomized and divided into three treatment groups: group 1 (the control group) received sesame oil, group 2 was given 17?-estradiol benzoate, and group 3 received 17?-estradiol benzoate plus progesterone. The body weight and food consumption of each rat were determined daily. Serum leptin levels and leptin mRNA expression were measured by ELISA and quantitative RT-PCR, respectively. Food consumption in the control group was significantly higher (P<0.05) than that in groups 2 and 3, although body weight did not significantly differ among the three groups. The serum leptin concentration and leptin mRNA expression were significantly higher (P<0.05) in groups 2 and 3 than in group 1, but no significant difference existed between groups 2 and 3. In conclusion, estrogen influenced food intake via the modulation of leptin signaling pathway in ovariectomized rats.
Project description:The nucleus accumbens plays a major role in the response of mammals to cocaine. In animal models and human studies, the addictive effects of cocaine and relapse probability have been shown to be greater in females. Sex-specific differential expression of key transcripts at baseline and after prolonged withdrawal could underlie these differences. To distinguish between these possibilities, gene expression was analyzed in four groups of mice (cycling females, ovariectomized females treated with estradiol or placebo, and males) 28 days after they had received seven daily injections of saline or cocaine. As expected, sensitization to the locomotor effects of cocaine was most pronounced in the ovariectomized mice receiving estradiol, was greater in cycling females than in males, and failed to occur in ovariectomized/placebo mice. After the 28-day withdrawal period, RNA prepared from the nucleus accumbens of the individual cocaine- or saline-injected mice was subjected to RNA sequencing analysis. Baseline expression of 3% of the nucleus accumbens transcripts differed in the cycling female mice compared with the male mice. Expression of a similar number of transcripts was altered by ovariectomy or was responsive to estradiol treatment. Nucleus accumbens transcripts differentially expressed in cycling female mice withdrawn from cocaine exhibited substantial overlap with those differentially expressed in cocaine-withdrawn male mice. A small set of transcripts were similarly affected by cocaine in the placebo- or estradiol-treated ovariectomized mice. Sex and hormonal status have profound effects on RNA expression in the nucleus accumbens of naive mice. Prolonged withdrawal from cocaine alters the expression of a much smaller number of common and sex hormone-specific transcripts.
Project description:<h4>Introduction</h4>Acute kidney injury is a serious,sexually dimorphic perioperative complication, primarily attributed to hypoperfusion. We previously found that estradiol is renoprotective after cardiac arrest and cardiopulmonary resuscitation in ovariectomized female mice. Additionally, we found that neither estrogen receptor alpha nor beta mediated this effect. We hypothesized that the G protein estrogen receptor (GPR30) mediates the renoprotective effect of estrogen.<h4>Methods</h4>Ovariectomized female and gonadally intact male wild-type and GPR30 gene-deleted mice were treated with either vehicle or 17?-estradiol for 7 days, then subjected to cardiac arrest and cardiopulmonary resuscitation. Twenty four hours later, serum creatinine and urea nitrogen were measured, and histologic renal injury was evaluated by unbiased stereology.<h4>Results</h4>In both males and females, GPR30 gene deletion was associated with reduced serum creatinine regardless of treatment. Estrogen treatment of GPR30 gene-deleted males and females was associated with increased preprocedural weight. In ovariectomized female mice, estrogen treatment did not alter resuscitation, but was renoprotective regardless of GPR30 gene deletion. In males, estrogen reduced the time-to-resuscitate and epinephrine required. In wild-type male mice, serum creatinine was reduced, but neither serum urea nitrogen nor histologic outcomes were affected by estrogen treatment. In GPR30 gene-deleted males, estrogen did not alter renal outcomes. Similarly, renal injury was not affected by G1 therapy of ovariectomized female wild-type mice.<h4>Conclusion</h4>Treatment with 17?-estradiol is renoprotective after whole-body ischemia-reperfusion in ovariectomized female mice irrespective of GPR30 gene deletion. Treatment with the GPR30 agonist G1 did not alter renal outcome in females. We conclude GPR30 does not mediate the renoprotective effect of estrogen in ovariectomized female mice. In males, estrogen therapy was not renoprotective. Estrogen treatment of GPR30 gene-deleted mice was associated with increased preprocedural weight in both sexes. Of significance to further investigation, GPR30 gene deletion was associated with reduced serum creatinine, regardless of treatment.
Project description:Testosterone can be safely and effectively administered to estrogen-treated post-menopausal women experiencing hypoactive sexual desire. However, in the United States and Canada, although it is often administered off-label, testosterone co-administered with estradiol is not a federally approved treatment for sexual arousal/desire disorder, partly because its mechanism is poorly understood. One possible mechanism involves the aromatization of testosterone to estradiol. In an animal model, the administration of testosterone propionate (TP) given in combination with estradiol benzoate (EB) significantly increases sexually appetitive behaviors (i.e., solicitations and hops/darts) in ovariectomized (OVX) Long-Evans rats, compared to those treated with EB-alone. The goal of current study was to test whether blocking aromatization of testosterone to estradiol would disrupt the facilitation of sexual behaviors in OVX Long-Evans rats, and to determine group differences in Fos immunoreactivity within brain regions involved in sexual motivation and reward. Groups of sexually experienced OVX Long-Evans rats were treated with EB alone, EB+TP, or EB+TP and the aromatase inhibitor Fadrozole (EB+TP+FAD). Females treated with EB+TP+FAD displayed significantly more hops and darts, solicitations and lordosis magnitudes when compared to EB-alone females. Furthermore, TP, administered with or without FAD, induced the activation of Fos-immunoreactivity in brain areas implicated in sexual motivation and reward including the medial preoptic area, ventrolateral division of the ventromedial nucleus of the hypothalamus, the nucleus accumbens core, and the prefrontal cortex. These results suggest that aromatization may not be necessary for TP to enhance female sexual behavior and that EB+TP may act via androgenic pathways to increase the sensitivity of response to male-related cues, to induce female sexual desire.
Project description:Olanzapine is an orexigenic antipsychotic drug associated with serious metabolic adverse effects in humans. Development of valid rodent models for antipsychotic-induced metabolic adverse effects is hampered by the fact that such effects occur in females only. Estradiol is a predominant female hormone that regulates energy balance. We hypothesized that the female-specific hyperphagia and weight gain induced by olanzapine in the rat are dependent on the presence of estrogens.Female sham-operated or ovariectomized rats were treated with a single injection of olanzapine depot formulation. Food intake, body weight, plasma lipids, lipogenic gene expression, energy expenditure, and thermogenic markers including brown adipose tissue uncoupling protein 1 protein levels were measured. Olanzapine was also administered to ovariectomized rats receiving estradiol replacement via the subcutaneous (peripheral) or intracerebroventricular route.Orexigenic effects of olanzapine were lost in ovariectomized female rats. Ovariectomized rats treated with olanzapine had less pronounced weight gain than expected from their food intake. Accordingly, brown adipose tissue temperature and protein levels of uncoupling protein 1 were elevated. Replacement in ovariectomized rats with either peripherally or centrally administered estradiol reduced food intake and body weight. Cotreatment with olanzapine blocked the anorexigenic effect of peripheral, but not central estradiol.Our results indicate that the ovarian hormone estradiol plays an important role in olanzapine-induced hyperphagia in female rats and pinpoint the complex effects of olanzapine on the balance between energy intake and thermogenesis.
Project description:Epidemiological studies have indicated that postmenopausal women have a higher incidence of intracranial aneurysms than men in the same age group.To investigate whether estrogen or estrogen receptors (ERs) mediate protective effects against the formation of intracranial aneurysms.Intracranial aneurysms were induced in mice by combining a single injection of elastase into the cerebrospinal fluid with deoxycorticosterone acetate salt hypertension. The mice were treated with estrogen (17?-estradiol), an ER? agonist (propyl pyrazole triol), and an ER? agonist (diarylpropionitrile) with and without a nitric oxide synthase inhibitor.The ovariectomized female mice had a significantly higher incidence of aneurysms than the male mice, which was consistent with findings in previous epidemiological studies. In ovariectomized female mice, an ER? agonist, but not an ER? agonist or 17?-estradiol, significantly reduced the incidence of aneurysms. The protective effect of the ER? agonist was absent in the ovariectomized ER? knockout mice. The protective effect of the ER? agonist was negated by treatment with a nitric oxide synthase inhibitor.The effects of sex, menopause, and estrogen treatment observed in this animal study were consistent with previous epidemiological findings. Stimulation of estrogen receptor-? was protective against the formation of intracranial aneurysms in ovariectomized female mice.