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PubMed1992

Perinatal exposure to morphine affects adult sexual behavior of the male golden hamster.

Duromorph, a long-acting form of morphine, was administered to pregnant golden hamsters and/or their pups over the last 4 days of pregnancy and/or the first 4 days after birth. As adults, offspring were gonadectomized, primed with estrogen and progesterone, and tested for their ability to display feminine sexual behavior when placed with a stud male. They were then given testosterone over a 4-week period and tested for their ability to display masculine sexual behavior in the presence of a receptive female. Perinatal morphine exposure had little effect on the females' ability to display either feminine or masculine sexual behavior. In contrast, feminine sexual behavior was significantly enhanced in males exposed to morphine over the perinatal period. This suggests that exposure to opiates during the critical period of sexual differentiation may prevent the defeminization process in this species.

Animals↗
PubMed1980

Sexual behavior in male rats following intracerebral estrogen application.

The effects on sexual behavior and morphology of estradiol benzoate (EB) applied directly to the medial preoptic nucleus were assessed in three groups of male rats with varying sexual behavior potentials. High levels of lordotic behavior were observed in all EB-treated groups. Cholesterol was uniformly ineffective. Central EB failed to facilitate male copulatory behavior in any group. However, there was evidence that cannula implantation may have impaired the potential for male behavior. Significant reductions in testis and epididymis weights were evident in some but not all EB-treated males. It was concluded that EB can activate lordotic behavior consistently in male rats if applied in sufficient amounts to the medial preoptic region.

Animals↗
PubMed1987

Maintenance of progesterone-facilitated sexual behavior in female rats requires continued hypothalamic protein synthesis and nuclear progestin receptor occupation.

The role of ongoing progesterone-directed protein synthesis and hypothalamic cell nuclear progestin receptor occupation in maintaining the duration of the period of sexual receptivity was determined in ovariectomized rats treated with 500 micrograms progesterone 44 h after receiving 2 micrograms estradiol benzoate. Injection of the protein synthesis inhibitor anisomycin (100 mg/kg BW) either 2 or 10 h after progesterone treatment resulted in decreased levels of both receptive and proceptive sexual behavior. Similarly, injection of RU 486, an antiprogestin, 2, 6, or 10 h after progesterone injection resulted in inhibition of sexual behavior within 4-8 h after administration. Using a modified cell nuclear isolation technique for the exchange assay of nuclear-bound progestin receptors, elevated levels of progestin binding in hypothalamic cell nuclear fractions were detected as late as 14 h after progesterone injection. By 18 h after progesterone injection, nuclear progestin receptor levels had returned to baseline, a time when the period of sexual behavior had terminated in similarly treated animals. These data suggest that continued progesterone action in hypothalamic cell nuclei is required for the maintenance of progesterone-facilitated sexual behavior in the female rat. Furthermore, they suggest that progesterone action maintains sexual responsiveness by altering the synthesis of a short-lived protein or set of proteins.

Animals↗
PubMed1987

The effect of season on the induction of sexual behavior by estradiol in female rhesus monkeys.

Rhesus monkeys housed in an outdoor environment are seasonal breeders, with ovulations and concomitant sexual behavior limited to the fall and winter months. To determine if there is a seasonal difference in the capacity of physiological levels of estradiol (E2) to induce sexual behavior in ovariectomized rhesus monkeys housed outdoors, subjects living in a social group were treated with subcutaneous E2 implants in a counter-balanced design during the nonbreeding season (May-July) and during the breeding season (September-November). Serum E2 levels were monitored by obtaining blood samples twice a week. Three levels of E2 were studied: baseline (less than 30 pg/ml), follicular (100 pg/ml), and periovulatory (200 pg/ml). Two of five adult males in the group were injected with human chorionic gonadotropin (hCG) twice a week to insure that males with high testosterone levels were present during each season. Focal observations of behavior of 15 minutes' duration on each subject were conducted 5 days per week, with frequencies and durations of social, sexual, and solitary behaviors recorded. Concomitant 2-h group scans were made to record all occurrences of mounting behavior. Neither heterosexual serial mounting nor seminal plugs were ever observed in E2-treated females during the summer months. In contrast, copulation and seminal plugs were observed in subjects at both treatment levels during the fall. While E2-treated females engaged in homosexual mounting behavior during both summer and fall, E2 treatment resulted in heterosexual copulation only during the fall. Changes in patterns of social behavior paralleled changes in sexual behavior and were significantly affected by treatment and season, with more male-female interactions during the fall months.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Sexual behavior among adolescent women at high risk for sexually transmitted infections.

BACKGROUND: The temporal pattern of partners and sexual encounters may be key factors in the acquisition and transmission of sexually transmitted diseases (STDs). Behavior among adolescent women is of particular interest because they frequently have the highest prevalence and incidence of infection. GOAL: To examine coital diary data collected during a 7-month longitudinal study of young women at high risk of STDs and to describe their sexual behaviors, with particular attention to issues of partner sequence and overlap. STUDY DESIGN: A 7-month longitudinal study of young women infected with or having a sexual contact infected with Neisseria gonorrhoeae, Chlamydia trachomatis, or Trichomonas vaginalis attending the STD clinic or one of four neighborhood adolescent health clinics. Data were collected at enrollment and at 1, 3, 5, and 7-month follow-up visits. Coital diaries were kept between visits. RESULTS: The average frequency of coital events was 0.94 per week. The median number of sexual partners during the follow-up period was one, and overlapping of partnerships was an uncommon occurrence. The number of days between the last coital event of a current relationship and the first encounter of a new relationship differed for those choosing a new partner (mean, 20.6 days) and those who returned to a previous partner (mean, 7.9 days; P < 0.001). CONCLUSION: Although at high risk for STDs, high-risk behavior was not common among the study population. Partner choice and the behavior of these partners may be more important elements than personal high-risk behavior in accounting for the high prevalence of sexually transmitted infections among inner-city adolescent women.

Adolescent↗
PubMed2005

Further studies on the rat posterodorsal medial amygdala: dendritic spine density and effect of 8-OH-DPAT microinjection on male sexual behavior.

The rat posterodorsal medial amygdala (MePD) is a component of the neural network that modulates male sexual behavior. Dendritic spines were counted in Golgi-impregnated bitufted and stellate neurons and from cells located in the medial and lateral MePD subregions. It was also studied the effect of 8-OH-DPAT, a 5-HT1A receptor agonist, microinjected into the MePD on male sexual behavior. There were no significant differences in the dendritic spine density obtained from multipolar bitufted and stellate neurons (n = 48 cells in each group; p > 0.05) or in the data from the medial or the lateral MePD (n = 48 neurons per region; p > 0.05). Rats were stereotaxically microinjected into the MePD with saline (0.2 microl, n = 6) or 8-OH-DPAT (0.1 and 1.0 microg/0.2 microl, n = 6 and 5, respectively). Behavioral recordings prior to surgery and "non-target" microinjections served as additional control data. 8-OH-DPAT 1.0 microg decreased the latencies to intromission and ejaculation, the postejaculatory refractory period and the mount frequency when compared to control pre-surgery data (p < 0.05). When compared among groups, 8-OH-DPAT 1.0 microg promoted the highest percentage reduction in the postejaculatory refractory period. Saline and injections in the vicinity of MePD did not promote relevant effects on ejaculation (p > 0.05). Results indicate that a similar dendritic spine density can be found in morphologically different populations of MePD neurons and, 8-OH-DPAT can facilitate male sexual behavior by acting on postsynaptic 5-HT1A receptors in this brain area.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1999

Temporal aspects of female musk shrew (Suncus murinus) sexual behavior.

The effects of testing condition on sexual behavior were examined in female musk shrews (Suncus murinus). Females were tested in 2 conditions, a pair test and a paced test. The pair test was similar to traditional sex test conditions in which the female and male are placed into the same chamber together until mating occurs. The paced condition allowed the female to leave the male's chamber and revisit him at will, thus "pacing" the interaction. Females displayed receptivity continuously for 14 days in both conditions. In the paced condition, females were less likely to become receptive within 30 min and mate to ejaculation. However, few additional differences were found between test conditions. Because this is the 1st experiment to use a pacing test paradigm in a species with induced ovulation, the authors speculate that the absence of pacing behavior during mating may be shown by other species that have induced ovulation.

Animals↗
PubMed2005

Medroxyprogesterone acetate acutely facilitates and sequentially inhibits sexual behavior in female rats.

Medroxyprogesterone acetate (MPA), a synthetic progestin commonly used in contraception and hormone replacement therapy, appears to inhibit libido in women, but little is known about the mechanisms through which it may exert this effect. We compared the acute and sequential actions of MPA and natural progesterone (P4) on sexual behavior in female rats to test the hypothesis that MPA inhibits sexual behavior, at least in part, by acting as a potent progesterone receptor (PR) agonist. Ovariectomized females were placed in one of three dose groups (high, mid, or low), and each subject was tested under three different conditions (MPA, P4, and vehicle). The order of progestin treatment was balanced among subjects, and within each dose group equimolar quantities of MPA and P4 were administered. During each trial, females were injected with estradiol benzoate (EB, 4 mug) followed by one of three progestin treatments (MPA, P4, or vehicle) at +44 h, and behavioral testing at +48 h. On the next day, all females were given a standard 500-microg injection of P4 at +68 h and were tested again for sexual behavior at +72 h. On the first day of behavioral testing, both MPA and P4 induced a pronounced rise in receptive and proceptive behavior at the mid and high doses, but at the lowest dose MPA had a much greater effect in comparison to P4. On the second day of behavioral testing, MPA attenuated the expression of proceptive and receptive behavior at both the mid and high doses, whereas P4 only attenuated the expression of lordosis and only did so at the highest dose. These findings illustrate that MPA and P4 have a similar impact on sexual behavior in female rats and suggest that the inhibitory effects of MPA may be attributable, at least in part, to its potent effects at the progesterone receptor.

Animals↗
PubMed2004

Fertilization success and sexual behavior in male medaka, Oryzias latipes, exposed to tributyltin.

We evaluated the effects of tributyltin (TBT), polychlorinated biphenyls (PCBs), and a mixture of TBT and PCBs on reproduction, gonadal histology, and sexual behavior in Japanese medaka (Oryzias latipes). We administered TBT (1 microg g(-1) body weight [b.w.] daily), PCBs (1 microg g(-1) b.w. daily), or both to medaka for 3 weeks. We assessed reproductive success during week 3 and the sexual behavior of male medaka after the exposure period. Fertilization success was significantly decreased in groups that received TBT. The profiles of fertility developed a bimodal distribution in the TBT and TBT+PCBs groups, and the numbers of males that performed "following" and "dancing" were significantly decreased in the TBT+PCBs group. The frequency of "dancing" also decreased after treatment with TBT, whereas fish that received PCBs only showed no difference in sexual behavior. Testes that had oocytes showed normal spermatogenesis, even though two of the five males treated with TBT+PCBs had some indication of testis-ova, which did not occur in any other group. Our results indicate that TBT, but not PCBs, affects sexual behavior and reproduction in medaka.

Animals↗
PubMed1989

Sexual behavior and its pheromonal regulation in ascosporogenous yeasts.

We reviewed our investigations on sexual behaviors and interactions including sexual cell agglutination and pheromone action mainly in non-conventional yeasts, Hansenula anomala, H. wingei, Pichia amethionina, P. heedi, P. opuntiae, Saccharomyces kluyveri, S. globsus, S. exiguus, Saccharomycodes ludwigii. The techniques and genetic models including the cassette model and alpha 1-alpha 2 hypothesis which had been developed largely in S. cerevisiae were applicable to these yeasts in principle. The sexual agglutination was distinctly species-specific while sex pheromones were cross-reactive beyond species' barriers. The successful induction of heterothallic strains from homothallic strains in S. exiguus by mutagenesis enabled to the subsequent biochemical and genetical analysis of sexual behavior in the yeast. The phylogenetic consideration on sex differentiation is also included.

Agglutination↗
PubMed1985

Presence of a neural mechanism for the expression of female sexual behaviors in the male rat brain.

Facilitatory and inhibitory neural mechanisms involved in the expression of female sexual behaviors in male rats were examined with a dual operation technique. Male rats were castrated and the preoptic area was dorsally deafferented (anterior roof deafferentation, ARD) in order to remove the forebrain lordosis-inhibitory system. Male rats with ARD displayed not only lordosis but also soliciting behaviors in response to 2 micrograms estradiol benzoate (EB) and 0.5 mg progesterone (P). The ARD male rat then received a second operation involving the hypothalamus or lower brain stem, i.e., the ventromedial nucleus and the adjacent area (ventromedial hypothalamus, VMH) were damaged by a radiofrequency lesion generator; the hypothalamus de-efferented anterolaterally by means of a Halász knife cut posterior to the suprachiasmatic nucleus (ADC) or lesions of the pontine periventricular gray and the adjacent area (dorsomedial tegmental lesion, DMTL). The DMTL effectively suppressed lordosis in EB-P-primed male rats with ARD. Only 1 of 14 ARD-DMTL males showed lordosis. In contrast, the VMH lesions or the ADC failed to interfere with the facilitatory effect of ARD on female sexual behaviors in male rats tested with the same dose of EB-P. Thus, the pontine periventricular gray plays a critical role for lordosis regulation in males. These results suggest that the male rat brain possesses the minimal neural mechanism for the expression of female sexual behaviors associated with the development of the strong forebrain lordosis-inhibiting system.

Afferent Pathways↗
PubMed1984

Lisuride, LY-141865, and 8-OH-DPAT facilitate male rat sexual behavior via a non-dopaminergic mechanism.

In agreement with previous results from this laboratory, the ergot derivative lisuride (0.4 mg/kg IP) and the ergot congener 8-OH-DPAT (0.25 mg/kg IP) produced a marked facilitation of male rat sexual behavior. Furthermore, another ergot compound, the dopamine-2 selective agonist LY-141865 (2.5-20 mg/kg IP), was shown to facilitate male rat sexual behavior to the same degree. Neither the effects produced by LY-141865, nor the effects produced by lisuride or 8-OH-DPAT, were antagonized by pretreatment with the dopamine receptor blocking agent haloperidol, 0.16 mg/kg IP. A higher dose of haloperidol (0.32 mg IP), which produced clear extrapyramidal symptoms, was also ineffective in antagonizing the lisuride- or 8-OH-DPAT-induced facilitation of male rat sexual behavior. It is concluded that the stimulation of male rat sexual behavior produced by ergot and ergot-like drugs is mediated via a non-dopaminergic mechanism.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1998

Anatomical interrelationships of the medial preoptic area and other brain regions activated following male sexual behavior: a combined fos and tract-tracing study.

The medial preoptic nucleus (MPN) is an essential site for the regulation of male sexual behavior. Previous studies using c-fos as a marker for neural activation have shown that copulation increased c-fos expression in the MPN. Neural activation was also present in brain regions that are connected with the MPN and are involved in male sexual behavior, including the posteromedial bed nucleus of the stria terminalis (BNSTpm), posterodorsal preoptic nucleus (PD), posterodorsal medial amygdala (MEApd), and parvocellular subparafascicular thalamic nucleus (SPFp). The present study investigated whether the copulation-induced, activated neurons in these brain regions are involved in the bidirectional connections with the MPN. Therefore, mating-induced Fos expression was combined with application of anterograde (biotinylated dextran amine) or retrograde (cholera toxin B subunit) tracers in the MPN. The results demonstrated that neurons in the BNSTpm, PD, MEApd, and SPFp that project to the MPN were activated following copulation. However, in males that displayed sexual behavior but did not achieve ejaculation, few double-labeled neurons were evident, although both retrogradely labeled neurons and Fos-immunoreactive cells were present. In addition, retrograde neurons that expressed Fos were located in discrete subdivisions within the brain regions studied, where Fos is induced after ejaculation. Likewise, anterogradely labeled fibers originating from the MPN were not distributed homogeneously but were particularly dense in these discrete subdivisions. These results demonstrate that copulation-induced Fos-positive neurons in specific subdivisions of the BNSTpm, PD, MEApd, and SPFp have bidirectional connections with the MPN. Taken together with previous findings, this supports the existence of a discrete subcircuit within a larger neural network underlying male sexual behavior.

Afferent Pathways↗
PubMed1988

Control of feeding and sexual behaviors by neuropeptide Y: physiological implications.

Recent evidence suggests that a variety of hypothalamic neuropeptides may mediate interneuronal communication to coordinate diverse neuroendocrine and behavioral functions. In this work, we describe the effects of neuropeptide Y (NPY) on feeding and sexual behaviors. We observed that central administration of bolus NPY stimulated a robust, dose-related feeding response in satiated male and female rats. Continuous NPY receptor activation also evoked dose-related, intermittent feeding in a manner normally observed during nocturnal feeding. It appears that the paraventricular nucleus in the hypothalamus may be the primary site of NPY action because the anticipated reciprocal changes in NPY concentrations, in response to food deprivation followed by ad libitum food intake, occurred only in this site. Additional findings revealed that NPY-induced feeding may follow either substantial reduction or complete restraint of an inhibitory influence on feeding mediated by alpha 2-adrenoreceptor systems in satiated rats. Further, NPY was found to suppress male and female sexual behaviors. The suppressive effects on sexual behavior were apparent prior to or at the time of the onset of feeding after NPY administration. These observations may provide a neurochemical basis for clinical and animal studies on disorders of feeding associated with diminished reproductive functions.

Animals↗
PubMed1994

High risk sexual behavior and alcohol consumption among bar-going gay men.

OBJECTIVES: To determine whether alcohol use prior to sexual behavior influenced the occurrence of unprotected anal intercourse among bar-going gay men. METHODS: Anonymous AIDS behavioral risk surveys were administered to men entering gay bars in 16 cities on three nights in February 1993 in six states in the United States. RESULTS: Of the 1519 men who completed the survey, 85% were current alcohol drinkers. Men who had unprotected anal intercourse after consuming alcohol drank more and reported more incidents of unprotected anal intercourse than men who had unprotected anal intercourse but not after drinking. Overall, unprotected anal intercourse occurred less frequently after alcohol consumption than without prior consumption. CONCLUSIONS: This study found that heavy alcohol use and frequent high-risk sexual behavior occurred among the same individuals. However, we found no evidence for a causal link between alcohol use and unprotected sexual behavior in this sample of bar-going gay men.

Adult↗
PubMed1995

Regulation of masculine sexual behavior: involvement of brain opioids and dopamine.

In recent years much has become known about the substrates in the brain involved in the regulation of masculine sexual behavior and the involvement of specific neurochemicals in these brain areas. In the present paper the experimental data concerning the involvement of a number of brain areas in sexual behavior are reviewed, in relation to an incentive motivational theory of sexual behavior. The review is restricted to the involvement of opioids and dopamine, of which the role in sexual motivation and behavior is best documented. Opioids in the medial preoptic area (mPOA) impair sexual performance, although the endogenous opioids systems may be quiescent in normal, sexually active rats. Dopamine in the mPOA has a facilitative role in the masculine sexual performance. The corticomedial amygdala is involved in processing of sensory information, especially olfactory stimuli, which are subsequently directed towards the mPOA. Local beta-endorphin infusion interferes with this processing. Endogenous opioids in the ventral tegmental area activate the mesoaccumbens dopamine system and stimulate the sexual motivation. Increased dopamine transmission in the nucleus accumbens correlates with increased sexual motivation and vice versa. The basolateral amygdala plays an essential role in the association of environmental stimuli with reward and therefore in the expression of conditioned sexual motivation. Finally, the reviewed data are integrated and a comprehensive view on the relations between various neural substrates is composed.

Animals↗
PubMed1996

Fos immunoreactivity in the rat brain following consummatory elements of sexual behavior: a sex comparison.

In the present study a comparison was made between the distribution of Fos immunoreactivity in the brain of female and male rats following successive elements of sexual behavior. The distribution of Fos immunoreactivity following either mounting, eight intromissions or one or two ejaculations was compared with that in control animals. In both females, Fos immunoreactivity was induced in the medial preoptic nucleus, posteromedial part of the bed nucleus of the stria terminalis, posterodorsal part of the medial amygdala, and the parvicellular part of the subparafascicular thalamic nucleus. In addition, Fos immunoreactivity in females was induced in the ventrolateral part and the most caudoventral part of the ventromedial nucleus of the hypothalamus and in the premammillary nucleus. Differences between females and males were detected in the phases of sexual activity that resulted in Fos immunoreactivity in these brain areas, allowing more insight in the nature of the sensory and hormonal stimuli leading to the induction of Fos immunoreactivity. The posteromedial bed nucleus of the stria terminalis appears to be involved in chemosensory investigation, while specific distinct subregions are only activated following ejaculation. In addition, the parvicellular subparafascicular nucleus and the lateral part of the posterodorsal medial amygdala appear to be involved in the integration of viscero-sensory input. The neural circuitries underlying sexual behavior in males and females appear to be similar in terms of integration of sensory information. In males the medial preoptic nucleus may be regarded as the brain area where the integration of sensory and hormonal stimulation leads to the onset of male sexual behavior, while in females the ventrolateral part of the ventromedial hypothalamic nucleus appears to have this function. In addition, Fos immunoreactivity was distributed in distinct clusters in subregions with various brain areas in males and females. This was observed especially in the posteromedial bed nucleus of the stria terminalis and posterodorsal medial amygdala, but also in the parvicellular subparafascicular nucleus, ventromedial hypothalamic nucleus and ventral premammillary nucleus. It appears that relatively small subunits within these nuclei seem to be concerned with the integration of sensory and hormonal information and may play a critical role in sexual behavior.

Amygdala↗