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PubMedDate not supplied

Ethanol exposure during the last week of gestation in the rat: inhibition of the prenatal testosterone surge in males without long-term alterations in sex behavior.

In utero ethanol exposure decreases the prenatal testosterone (T) surge in male rats. To determine the functional significance of this suppression, we measured sex behavior in adult litter representatives of pregnant rats that were administered a fortified liquid diet containing 35% ethanol-derived calories from day 15 of gestation through parturition. Control dams were pair-fed an isocaloric liquid diet with the ethanol calories replaced by sucrose. Results from the behavioral studies showed that gonadally intact fetal alcohol-exposed (FAE) males exhibited little masculine sex behavior in the first of four weekly sessions. However, their behavior in the subsequent three tests was indistinguishable from pair-fed controls. Lordosis quotients in the same males following castration and estrogen and progesterone treatment were under 10%. In castrated FAE females, no effects of prenatal ethanol exposure were observed in masculine behaviors following androgen replacement or feminine sex behaviors following estrogen and progesterone replacement. Additional studies measured the duration of prenatal ethanol exposure necessary to inhibit the prenatal T surge in order to determine whether the inhibition was due to a direct effect of the drug. Results revealed an inhibition of the surge in males exposed to ethanol from days 14 through 20 of pregnancy, days 14 through 16 of pregnancy, or days 17 through 20 of pregnancy. A normal surge of T was observed on days 18-19 of gestation in control fetuses. These findings indicate that ethanol does not have to be present in blood at the time of the surge to have an inhibitory effect. They also reveal that the surge can be inhibited with as little as 24-36 h of ethanol exposure prior to its normal appearance on day 18 of gestation. In spite of this inhibition of the prenatal T surge, the behavioral results indicate that normal masculinization and defeminization of sex behavior occurs in FAE males exposed to ethanol after the beginning of the period of differentiation of the hypothalamus and testes.

Animals↗
PubMed1986

Sex behavior and the sexually dimorphic hypothalamic nucleus in male Zucker rats.

To determine whether or not impaired male sex behavior in obese male Zucker rats is accompanied by any anatomical alterations in a hypothalamic area implicated in the control of sex behavior, 6 lean and 5 obese male Zucker rats were studied behaviorally and anatomically at 14 months of age. Obese males showed markedly decreased male sex behavior relative to lean males, in spite of serum levels of testosterone and testicular weights comparable to those of lean rats. Obese rats had significant decreases in brain weight and volumes of sexually dimorphic nuclei per g of brain, relative to lean rats; volumes per g brain of other structures (paraventricular and suprachiasmatic nuclei) were not different between groups. It is suggested that an incomplete expression of sexually dimorphic features of the preoptic area-anterior hypothalamus, due perhaps to an impaired process of perinatal brain androgenization, may contribute to decreased male sex behavior in adult obese rats.

Animals↗
PubMed1995

Gender differences of reported safer sex behaviors within a random sample of college students.

This study investigated the frequency of safer sex behaviors with a random sample of sexually active college students (N = 315) at a university in the Northwest. The most frequent safer sex behaviors were discussion of contraceptives (58.6%), being more selective (46.5%), and reducing the number of sexual partners (43.6%). The least frequent safer sex behaviors included discussion of partner's sexual health prior to sexual behavior (26.1%), using condoms or dental dams (24.4%), one sexual partner (22.6%), and abstaining from sex as a safer sex practice (12.3%). The only two behaviors which indicated gender differences were (a) if they were being more selective as a safer sex practice and (b) reducing number of sexual partners as a safer sex practice. Women were more likely to state that they were " almost always" more selective than their male peers. Findings from this study indicated that a substantial number of students reported "risk factors" sexual practices. These findings indicated a need for HIV-prevention efforts.

Adult↗
PubMed1983

Effects on male sex behavior and preoptic dopamine neurons of hyperprolactinemia induced by MtTW15 pituitary tumors.

We have earlier reported that dopamine (DA) activity in the preoptic anterior hypothalamic (POA-AH) region of castrated rats is inhibited by testosterone and accelerated by PRL. These results suggested that dopaminergic neurons may play an important role in male copulatory behavior, particularly in the attenuation of sex behavior reported to be associated with hyperprolactinemia. We have now examined the effects of severe hyperprolactinemia on the POA-AH DA activity in association with any modifications of copulatory behavior. Sexually experienced adult male rats were castrated and implanted sc with Silastic implants containing testosterone to maintain serum testosterone levels in the range found in intact rats. Hyperprolactinemia was induced by inoculation of minced MtTW15 PRL secreting pituitary tumor fragments. Copulatory behavior was assessed at weekly intervals in hyperprolactinemic and control rats. During the period of tumor growth serum PRL levels increased logarithmically. Whereas sexual activity continued to improve in control rats, there was a marked decrease in several important parameters of copulatory behavior in hyperprolactinemic rats. The most dramatic decrease occurred in the percentage of tumor-bearing rats ejaculating which decreased progressively to zero at 6 weeks after tumor inoculation. Ejaculation frequency decreased and ejaculation latency increased in tumor-bearing rats before the complete disappearance of ejaculatory behavior. The deficits in copulatory behavior of hyperprolactinemic rats were accompanied in parallel studies by significant depletions of DA concentrations in the POA-AH. Further, neuronal activity, as evidenced by the turnover rates measured by rate of loss of DA after tyrosine hydroxylase inhibition with alpha-methyl paratyrosine, was markedly augmented in the POA-AH of hyperprolactinemic rats as compared to control animals. These findings disclose a close association between the acceleration in POA-AH DA activity and the attenuation of copulatory behavior induced by hyperprolactinemia and suggest the probability of an underlying role of the POA-AH DA neurons in male sex behavior normally induced by testosterone.

Animals↗
PubMed2006

Rat RFamide-related peptide-3 stimulates GH secretion, inhibits LH secretion, and has variable effects on sex behavior in the adult male rat.

A recently described avian neuropeptide, gonadotropin inhibitory hormone (GnIH), has been shown to have seasonal regulatory effects on the hypothalamic-pituitary-gonadotropin axis (HPG) in several avian species. In the bird, GnIH expression is increased during the photorefractory period and has inhibitory effects on the HPG. A recently described mammalian neuropeptide, RF-amide-related peptide-3 (RFRP-3), may be genetically related and functionally similar to this avian neuropeptide. The purposes of this study were to first see if rat RFRP-3 is expressed in the male rat brain and second to determine if ICV injections of RFRP-3 will have effects on feeding and sex behaviors, as well as hormone release from the anterior pituitary. Results confirm other studies in that immunoreactive cell bodies and fibers are observable in areas of the male rat brain known to control the HPG and feeding and sex behaviors. RFRP-3 fibers are also observed in close proximity to GnRH immunoreactive cell bodies. Behavioral tests indicate that high but not low ICV RFRP-3 (500 vs. 100 ng, respectively) significantly (p<0.05) suppressed all facets of male sex behavior while not having any observable effects on their ability to ambulate. Sex behavior was later exhibited when those same male rats received the ICV vehicle. While suppressing sex behavior, ICV RFRP-3 significantly (p<0.05) increased food intake compared to controls. ICV RFRP-3 also significantly reduced plasma levels of luteinizing hormone but increased growth hormone regardless of the time of day; however, at no time did RFRP-3 alter plasma levels of FSH, thyroid hormone, or cortisol. These results indicate that although RFRP-3 has similar effects on LH as observed with GnIH in avian species, in the rat RFRP-3 has additional roles in regulating feeding and growth.

Animals↗
PubMed2006

Immunolesions of glucoresponsive projections to the arcuate nucleus alter glucoprivic-induced alterations in food intake, luteinizing hormone secretion, and GALP mRNA, but not sex behavior in adult male rats.

Metabolic signals such as insulin, leptin and glucose are known to alter hypothalamic function. Although insulin and leptin are known to directly alter hypothalamic areas that regulate reproduction, the mechanisms by which glucose alters reproductive function are not as clear. Catecholaminergic neurons in the A1/C1 region in the hindbrain are glucose-responsive and project to the arcuate nucleus. To determine if this pathway is involved in the regulation of sex behavior and luteinizing hormone (LH) secretion, this catecholaminergic pathway was lesioned with injections of saporin conjugated with anti-dopamine-beta-hydroxylase (DSAP) or unconjugated saporin (SAP) in adult male rats. Rats were given glucoprivic challenges and feeding and sex behavior was observed. As was expected, the DSAP-treated rats showed decreased feeding during glucoprivation (250 mg/kg 2-deoxy-D-glucose, 2DG) compared to SAP controls. Glucoprivation caused a significant reduction in sex behavior in both SAP and DSAP animals equally, compared to saline treatments (p < 0.05). At the end of the experiment, animals were given a final challenge with 2DG or saline, euthanized by decapitation and trunk blood was assayed for plasma LH levels. In situ hybridization analysis revealed that 2DG treatment caused a significant reduction in GALP mRNA in SAP controls compared to saline treatment. This reduction in GALP mRNA was prevented with DSAP treatment. In SAP animals, 2DG elicited a significant decrease in plasma LH levels (p < 0.05); this reduction in plasma LH was absent in the DSAP-treated male rats. These data indicate that the A1/C1 efferents to the ventromedial hypothalamus are involved in the glucostatic regulation of GALP mRNA, feeding behavior and LH secretion, but not sex behavior in the adult male rat.

Animals↗
PubMed1995

Same-sex behavior, sexually transmitted diseases and HIV risks among young northern Thai men.

OBJECTIVES: To assess the risks for HIV infection and sexually transmitted diseases (STD) among young northern Thai men who have sex with men (MSM), and to examine the possible role of male same-sex behavior in the northern Thai HIV/AIDS epidemic. METHODS: Two cohorts of northern Thai military conscripts and one cohort of recently discharged conscripts, a total of 2047 men, were studied. Data were collected by interview on behavioral risk factors, and sera were examined for syphilis and HIV-1 antibodies. Univariate and multiple logistic regression analyses were used to determine risk factors associated with HIV and STD, and to assess the frequency and patterns of same-sex behaviors among these men. RESULTS: Of 2047 men, 134 (6.5%) reported one or more male lifetime sex partners. Of these MSM, 130 (97.0%) also had female partners, and four (3.0%) had exclusively male partners. Compared with men who reported only female sex partners, MSM had a higher number of lifetime sex partners, a higher mean number of female sex partners, more female and male commercial sex worker (CSW) partners, and were more likely to be married. MSM were significantly more likely than exclusively heterosexual men to report having had any STD [odds ratio (OR), 2.72], gonorrhea (OR, 2.05), syphilis (OR, 3.17), non-gonococcal urethritis (OR, 4.54) and penile discharges (OR, 6.24). They were at borderline increased risk for HIV infection [OR, 1.51; 95% confidence interval (CI), 0.95-2.41]. Men with more than one lifetime male sex partner compared with those with only one partner were significantly more likely to be HIV-infected (OR, 2.81; 95% CI, 1.09-7.19). CONCLUSIONS: Northern Thai MSM are a high-risk population for STD, including HIV. Reported same-sex behavior in this population appears to vary considerably with data collection techniques. HIV and STD prevention strategies aimed at changing unsafe sexual practices may need to be targeted to the general population of young Thai men.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Methoxychlor induces estrogen-like alterations of behavior and the reproductive tract in the female rat and hamster: effects on sex behavior, running wheel activity, and uterine morphology.

The current investigation was designed to determine if the pesticide methoxychlor (M) mimicked the effects of estrogen in the brain and on behavior. Running wheel activity (RWA) and sex behaviors were evaluated in this study because the role of estrogen in the regulation of these behaviors has been thoroughly established. M exposure at 400 mg/kg/day (90% pure) induced high levels of acyclic RWA and persistent vaginal estrus in the female rats. Following ovariectomy (ovx), RWA declined precipitously in controls but remained at high levels in M-treated-ovx females. M also produced estrogen-like alterations of the uterine endometrial epithelium, the ovary, and growth after ovx. In another study, ovx female rats were dosed with M at 200 mg/kg/day and then with progesterone (P). P acts as an antiestrogen and specifically suppresses estrogen-induced RWA. P blocks the synthesis of estrogen receptors in the CNS and reproductive tract but does not lower RWA induced by nonestrogenic mechanisms. After 14 days of M administration RWA was increased fourfold over the ovx-oil-treated females. Subsequently, P injections reduced RWA levels far below those seen when the ovx-M-treated rats were injected with oil. The P-induced decline represents a 95% inhibition of the M-induced increase in RWA. Subsequently, M-treated-ovx rats and hamsters were injected with P and tested for their ability to display reproductive behaviors when paired with a stud male. Female sexual behaviors are induced by the administration of estrogen followed by progesterone. In this study the M-treated females displayed reproductive behaviors, in contrast to the oil-treated rats and hamsters. The observation that the high levels of RWA induced by methoxychlor treatment in ovx rats can be suppressed by concurrent progesterone injections demonstrates that the increase in RWA is due to the estrogenic effects of methoxychlor on the CNS. The fact that methoxychlor, followed by P injections, induces behavioral estrus in the rat and hamster extends this estrogenicity to other areas in the CNS.

Animals↗
PubMed1983

Induction of male sex behavior in pony mares with testosterone propionate.

Two pony mares were administered 150 mg of testosterone propionate every other day for 20 days (ten injections) and every ten days there-after. An additional two mares and one stallion were not treated and served as controls. Testosterone propionate was dissolved in absolute ethanol and administered subcutaneously. Sex behavior tests were conducted 26 and 40 days after the first injection. Control mares exhibited very little male sex behavior. Both testosterone propionatetreated mares, however, exhibited mounting, sniffing, flehmen, biting and vocalization behavior in the presence of an estrous mare. The testosterone propionate-treated mares mounted and bit estrous mares more frequently than the stallion but exhibited less sniffing, flehmen and vocalization behavior in the presence of an estrous mare than the stallion. Testosterone propionate-treated mares and the stallion mounted an estrous mare 23.3 +/- 9.7 seconds and 172.5 +/- 22.5 seconds, respectively, after being introduced into the pen. Mares in estrus were mounted by the testosterone propionate-treated mares and the stallion an average of 4.0 +/- 1.3 and 1.0 +/- 0 times, respectively, during a ten-minute test. None of the non-estrous mares was ever mounted by the testosterone propionate-treated mares. In summary, testosterone propionate induced male sex behavior in intact mares and the testosterone propionate-treated mares effectively detected estrous mares.

Journal Article↗
PubMed2001

CNS region-specific oxytocin receptor expression: importance in regulation of anxiety and sex behavior.

The oxytocin receptor (OTR) is differentially expressed in the CNS. Because there are multiple mechanisms by which the OTR can be transcriptionally induced, we hypothesized that differences in OTR expression may be explained by activation of distinct signal transduction pathways and may be critical for the control of anxiety and sex behaviors. To determine the regulation and functional significance of this expression, we infused female rats with modifiers of protein kinases before assaying for behavior and oxytocin receptor binding. In the ventromedial nucleus of the hypothalamus (VMH), estrogen-dependent induction of oxytocin receptors required protein kinase C activation, and oxytocin infused here promoted female sex behavior but had no effect on anxiety. In contrast, dopamine controlled tonic oxytocin receptor expression in the central nucleus of the amygdala (cAmyg) through activation of protein kinase A, and oxytocin infused here was anxiolytic but had no effect on female sex behavior. Therefore, we have identified brain region-specific regulation of the OTR in the VMH and cAmyg. Distinct signal transduction pathways regulating receptor expression and binding in each brain region may mediate in part the ability of oxytocin to exert these differential behavioral effects.

Animals↗
PubMed1996

Effects of androgens and estrogens on sexual differentiation of sex behavior, scent marking, and the sexually dimorphic area of the gerbil hypothalamus.

Mating, marking and the sexually dimorphic area (SDA) were studied in male gerbils that were castrated or sham-operated on the day of birth and in females given testosterone (T) propionate or oil 1 day later. Other females received dihydrotestosterone (DHT), R1881, estradiol benzoate (EB), R2858, DHT and EB, or DHT and R2858. Females and control males were castrated as adults. Then half of each group was given T and tested for marking and male sex behavior. They were still exposed to T at perfusion. The rest were given EB and progesterone and were tested for marking and lordosis. They were perfused 1 month after hormone treatment ended. Neonatal castration eliminated mounting, decreased T-induced marking and increased lordosis in males. Neonatal exposure to TP decreased lordosis and increased mounting, intromission patterns and T-induced marking in females. DHT and R1881 did not affect marking or mating when given alone. EB and R2858 decreased lordosis and increased mounting. DHT enhanced the former effect but not the latter. Only combined treatments increased T-induced marking. Total SDA volume was not affected by neonatal treatments, but "dark volume" was largest in control males. The SDA pars compacta (SDApc) was seldom seen in females unless they received steroid neonatally but was present in males that were castrated neonatally. SDApcs of neonatal castrates and steroid-treated females differed, though, from SDApcs of control males in that they were smaller in the absence of T and did not enlarge when exposed to T. Another cell group, the cmSDApc, was affected by T neonatally but was not seen consistently in either sex. SDApc volume correlated positively with T-induced marking and an index of male sex behavior. Both SDApc and cmSDApc volumes correlated negatively with lordosis. The correlations with marking and male sex behavior probably reflect constraints on sexual differentiation rather than causal relationships since these behaviors persist when the SDApc is gone. The effects of direct manipulations of the SDApc on lordosis have not been studied.

Androgens↗
PubMed1975

Vitamin E and sex behavior in mice.

C57BL/6J male mice responded to dietary deficiency of vitamin E with reduction in spermatogenesis. Sex behavior and seminal vesicle weight were unaffected. Supplements of alphabeta-tocopherol (vitamin E) at 0.33 or 72 IU per day maintained spermatogenesis but did not affect seminal vesicles or sex behavior.

Animals↗
PubMed1981

Male sex behavior and testosterone concentrations in gilts administered testosterone propionate.

Two gilts were administered testosterone propionate and their subsequent plasma testosterone concentrations and male sex behavior were recorded. These were compared to testosterone concentrations and male sex behavior in boars. Testosterone propionate (75 mg) was administered to the gilts every other day for 20 days (induction scheme) and every 10 days there-after (maintenance scheme). Concentrations of testosterone in plasma were elevated to concentrations detected in the boars during the induction scheme. During the maintenance scheme, concentrations of testosterone appeared to be lower than in boars. At 20, 30 and 40 days following the first injection, sniffing, nosing and mating song behaviors were exhibited by the testosterone treated gilts similar in frequency to the boars. Mounting behavior was first detected 30 days following the first testosterone propionate injection, and by day 40, the frequency of mounting was greater than observed in boars.

Journal Article↗
PubMed2000

Drug use and HIV risk--related sex behaviors: a street outreach study of black adults.

BACKGROUND: Our street outreach project investigated the relationship between use of noninjecting drugs (alcohol, marijuana, cocaine) and human immunodeficiency virus (HIV) risk-related sex behaviors of black adults. The study focused on three HIV-related risks: multiple sex partners, unprotected sex, and drugs during sex. METHODS: Data for this study were collected in a street outreach community survey for a drug abuse and HIV intervention study in Birmingham, Ala. A total of 780 black men and women completed the survey. RESULTS: High-risk sex behaviors were far more prevalent among cocaine users than marijuana or alcohol users. A greater number of cocaine users reported having multiple sex partners, not using condoms, and using drugs during sex. Female cocaine users showed the same risk level for HIV infection as male cocaine users. CONCLUSIONS: Increased risk of HIV infection through sexual transmission is associated with use of noninjecting cocaine for both men and women. Condom use should be considered as a major component of HIV prevention programs.

Adult↗
PubMed1996

Nature needs nurture: the interaction of hormonal and social influences on the development of behavioral sex differences in rhesus monkeys.

Thirty years of research on early social and hormonal environments and their relationship to the expression of behavioral sex differences in rhesus monkeys are reviewed. These studies demonstrate that whether aggressive and submissive behaviors are sexually dimorphic depends primarily on the social and not the hormonal environment. Early rearing environments without mothers or allowing brief periods of peer interaction produced higher levels of male aggression and female submission. Presenting behavior was expressed more by females than males in environments with high male aggressivity and female submissiveness. No sex differences in presenting occurred in low aggressivity environments, unless monkeys were reared isosexually, when males presented more than females. Rough and tumble play and foot-clasp mounting were consistently exhibited more by males than females across all rearing environments studied, but rearing environment affected the degree of the sex difference. When reared isosexually males displayed less, and females more, foot-clasp mounting than when heterosexually reared. No social environment increased the low frequency of female rough and tumble play. Suppressing neonatal androgen in males did not effect any sexually dimorphic behavior. Prenatal androgen administration to genetic females masculinized many aspects of their juvenile behavior, consistently increasing rough and tumble play and foot-clasp mounting across different social environments. Thus the sexually dimorphic behaviors which showed the smallest variability across social contexts were the most profoundly affected by the prenatal hormonal environment. These studies demonstrate that the expression of consistent juvenile behavioral sex differences results from hormonally induced predispositions to engage in specific patterns of juvenile behavior whose expression is shaped by the specific social environment experienced by the developing monkey.

Animals↗
PubMed1982

Induction of male sex behavior in ewes with silastic implants containing testosterone propionate.

In the first of two experiments, ovariectomized ewes with silastic implants containing testosterone propionate had higher concentrations of plasma testosterone than ovariectomized ewes with silastic implants containing testosterone (4.0+/-.2 vs .8+/-.1 ng/ml). In the second experiment, one or two 10 cm silastic implants filled with testosterone propionate increased concentrations of plasma testosterone and induced male sex behavior in ovariectomized ewes similar to plasma testosterone levels and male sex behavior in rams. The interval from initiation of the treatment to the first behavior test in which mounting was consistently observed was 14.4+/-2.9 days and once mounting behavior was consistently induced, the testosterone treated ewes mounted estrous ewes an average of 10.7+/-1.3 times during a 10-minute test.

Journal Article↗