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PubMed1984

Estradiol benzoate treatment of an XY gonadal dysgenetic chacma baboon.

Behavioral studies of an XY gonadal dysgenetic chacma baboon under estradiol benzoate treatment were carried out. The dysgenetic individual and two ovariectomized conspecific control females were given a total of three testing series. The dysgenetic individual showed progressive success in her sexual interactions with her male partners and during her third testing series she was copulated with to ejaculation by five of the eight male partners. This study provides the first supportive evidence from a nonhuman primate for the predicted development of female sexual behavior in a genetic male deprived of testes prior to the sensitive period for sexual differentiation.

Animals↗
PubMed1985

Behavioral and physiological control of yolk synthesis and deposition in the female red-sided garter snake (Thamnophis sirtalis parietalis).

Ovarian recrudescence in female garter snakes, Thamnophis sirtalis parietalis, follows spring emergence from hibernation and mating. In the laboratory, courtship and mating stimuli significantly increased the proportion of female garter snakes becoming pregnant, although some noncourted nonmated controls also became pregnant. Females given artificial mating stimuli under anesthetic, without courtship stimuli, were no more likely than either noncourted, nonmated or anesthetized controls to become pregnant. Hormonal changes and yolk synthesis rapidly followed mating in both laboratory and field females; serum estradiol increased more than 10-fold in 2 days and serum calcium, a measure of yolk precursor lipoprotein (vitellogenin) concentration, increased more than two times in 10 days. Administration of exogenous estradiol stimulated yolk synthesis, but did not result in yolk deposition into ovarian follicles. However, administration of ovine follicle-stimulating hormone induced both hepatic yolk synthesis and yolk deposition. Our results are consistent with the hypotheses that courtship and copulation are facilitatory to ovarian recrudescence but neither alone nor in combination is necessary nor sufficient, and in this species yolk synthesis and yolk deposition are separately regulated.

Animals↗
PubMed1985

Studies of pericopulatory pregnancy blockage and the gestation period in deer mice (Peromyscus maniculatus).

It has previously been shown that female deer mice in cycling estrus that copulate with or are exposed to more than one male at the time of mating have a lower probability of delivering a litter than when mating with and being exposed to just one male. In the present research the effect of post-mating exposure to the bedding of a strange versus a familiar male was studied in females in postpartum estrus. In four experiments females in postpartum estrus were protected from pericopulatory pregnancy blockage, presumably by suckling-induced elevated prolactin levels. Varying female experience, number of ejaculations, and the presence of suckling pups had no effect on this protection. Thus, both the pericopulatory block and the Bruce effect (a more delayed type of pregnancy blockage) occur in cycling, but not suckling, females. This suggests that the two may have a common mechanism and leads to a new perspective in the search for adaptive significance. In addition, the subsequent gestation periods were prolonged in females nursing young; the length was affected by the number of pups weaned from the previous litter and the number of pups being carried.

Adaptation, Physiological↗
PubMed1988

Sexual coloration, plasma concentrations of sex steroid hormones, and responses to courtship in the female keeled earless lizard (Holbrookia propinqua).

The reproductive condition, steroid hormone concentrations in the plasma, and behavior of bright and plain female Holbrookia propinqua were examined. Bright females performed significantly more aggressive rejection of courtship than plain females. Bright females were significantly more likely than plain females to have follicles larger than 5.0 mm or oviductal eggs; females with large follicles or oviductal eggs had significantly higher concentrations of progesterone and androgen than those with small follicles and lacking oviductal eggs. Plasma progesterone, androgen, and estradiol levels in the females studied behaviorally were significantly higher for the bright females than for the plain ones. Females undergoing rapid brightening were significantly more likely to be sexually receptive and copulate than were either plain or fully brightened females. The role of sex steroid hormones in coloration and behavior and the adaptive value of chromatic signalling by females are discussed.

Aggression↗
PubMed1989

The influence of androgenic and estrogenic hormones on sexual behavior in castrated adult male pigs.

The objectives of these studies were to evaluate the influence of testosterone propionate (TP), estradiol cypionate (EC), dihydrotestosterone propionate (DHTP), EC + TP, EC + DHTP, and TP + DHTP on traits of masculine sexual behavior in castrated adult male pigs of different breeds. Masculine sexual behavior was restored and maintained by TP, whereas EC initially activated sexual behavior, including copulation and ejaculation, but was unable to sustain copulatory behavior for the 8- to 18-week periods that were evaluated. Treatment with DHTP was ineffective for stimulation of sexual behavior; thus, it is suggested that testosterone promotes some aspects of masculine sexual behavior in male pigs via aromatization to estrogen, but both androgen and estrogen are required for maintenance of the full complement of masculine sexual behavior traits.

Androgens↗
PubMed1990

Adrenal suppression and sexual initiation in group-living female rhesus monkeys.

Eight female rhesus monkeys living in an outdoor social group were studied for two menstrual cycles during the breeding season. During one cycle, adrenal steroids were suppressed for an average of 24 days using dexamethasone (0.6 mg/day) administered via subcutaneous osmotic minipumps. During the other cycle females were implanted with control pumps containing sterile water. Observers were blind to the treatments and treatment order was counterbalanced. Female sexual behavior was observed daily with each of two adult rhesus males. During dexamethasone treatment, cortisol levels were suppressed to less than 10% of control levels, and testosterone and androstenedione levels were suppressed to less than 50% of control, suggesting nearly total elimination of adrenal contribution to circulating androgen. All females showed hormonal evidence of ovulation. Adrenal suppression had no significant effect on female behavior, including approaches to the male and sexual solicits. In addition, no differences in any male behavior, including number of ejaculations, were seen between the two treatments. The continued cyclic copulation during adrenal suppression demonstrates that ovarian hormones are sufficient to modulate female rhesus sexual behavior and that adrenal androgens have little effect on the sexual behavior of intact, group-living rhesus females.

Adrenal Glands↗
PubMed1990

Sexual differentiation of behavior in the zebra finch: effect of early gonadectomy or androgen treatment.

Treatment of nestling zebra finches with estradiol benzoate (EB) has been shown to masculinize singing in females and demasculinize copulatory behavior in males, suggesting that sexual differentiation of these behaviors is under hormonal control such that testicular hormones induce the capacity for song and ovarian hormones suppress the capacity for mounting. Two experiments were carried out to obtain a more complete picture of sexual differentiation in this species. In Experiment 1, nestlings were injected daily for the first 2 weeks after hatching with testosterone propionate (TP), dihydrotestosterone propionate (DHTP), or a combination of DHTP and EB. As adults, birds were gonadectomized and implanted with TP prior to testing, then tested again after implantation with EB. Singing was not increased in females by any of the treatments. The only effect of either TP or DHTP given alone was defeminization of female proceptive behavior by DHTP. Thus androgens appear to have less influence than estrogens on sexual differentiation of behavior in this species. The combination of DHTP and EB demasculinized mounting in males. In Experiment 2, nestlings were gonadectomized at 7-9 days of age and implanted with TP prior to testing in adulthood. Early gonadectomy had little effect on later behavior; early castrated males sang, danced, and copulated normally and early ovariectomized females neither sang nor mounted.

Animals↗
PubMed1990

Effects of the nonsteroidal inhibitor R76713 on testosterone-induced sexual behavior in the Japanese quail (Coturnix coturnix japonica).

A new triazole derivative, R76713 (6-[4-chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1-methyl-1H- benzotriazole), was recently shown to inhibit aromatase selectively without affecting other steroid-metabolizing enzymes and without interacting with estrogen, progestin, or androgen receptors. This compound was tested for its capacity to intefere with the induction of copulatory behavior by testosterone (T) in castrated Japanese quail (Coturnix coturnix japonica). In a first experiment, R76713 inhibited (range 0.01 to 1 mg/kg) the activation of sexual behavior by T silastic implants and hypothalamic aromatase activity in castrated male quail in a dose-dependent manner. The 5 alpha- and 5 beta- reductases of T were not systematically affected. Stereotaxic implantation of R76713 in the medial preoptic area similarly blocked the behavior activated by systemic treatment with T, demonstrating that central aromatization of androgen is implicated in the activation of behavior. These inhibiting effects of R76713 on behavior were observed when implants were placed in the medial part of the nucleus preopticus medialis, confirming the implication of this brain area in the control of male copulatory behavior. Finally, the behavioral inhibition produced by R76713 could be reversed by simultaneous treatment with a dose of estradiol, which was not behaviorally effective by itself. This suggests that the behavioral deficit induced by the inhibitor was specifically due to the suppression of estrogen production. This also shows that the activation of copulatory behavior probably results from the interaction of androgens and estrogens at the brain level, as the two treatments separately providing these hormonal stimuli (T with the aromatase inhibitor on one hand and a low dose of estradiol on the other hand) had almost no behavioral effects but they synergized to activate copulation when given concurrently. These data confirm the critical role of preoptic aromatase in the activation of reproductive behavior and demonstrate that R76713 is a useful tool for the in vivo study of estrogen-dependent processes.

Animals↗
PubMed1992

Seasonal fluctuations in hormones and behavior of free-living male California ground squirrels (Spermophilus beecheyi).

Plasma testosterone (T), prolactin (PRL), and behavior were monitored concurrently in free-living male California ground squirrels (Spermophilus beecheyi). Male plasma T peaked in January, 2-3 months after males emerged from their annual period of estivation. PRL peaked 6 to 10 weeks after T. Temporal patterns of space use by males were directly correlated with plasma T levels, but seasonal maxima in rates of most monitored male behaviors occurred 4 weeks after the T peak. No monitored behavior rates were correlated with plasma PRL values. Yearling and adult males did not differ with respect to circulating levels of either T or PRL. Both groups of males mated in our study population, and did not differ significantly with respect to rates of most monitored behaviors. However, yearlings pursued fewer females, mated less frequently, and required more mounts to complete each copulation than did adults. We suggest that T serves an important priming function for various seasonally fluctuating behaviors, but also that mating experience might influence the efficiency of copulatory behavior in this species.

Animals↗
PubMed1994

Impairment of male copulatory behavior in rhesus monkeys following acute administration of cocaine.

Although numerous studies in nonhuman primates have demonstrated an influence of cocaine on behavior, no studies have yet examined whether cocaine affects sexual behavior in nonhuman primates. The objective of the present study was to examine the acute effects of cocaine on male copulatory behavior of rhesus monkeys. Administration of cocaine produced dose-dependent effects on male copulatory behavior, with monkeys taking significantly longer to initiate copulation (mount latency) and achieve an ejaculation (ejaculation latency) after receiving 200-800 micrograms/kg cocaine. Male copulatory behavior was not affected by cocaine at doses below 200 micrograms/kg. These results indicate that cocaine can acutely impair sexual behavior performance of male rhesus monkeys. Further study is needed to determine the possible long-term consequences of chronic cocaine administration on male sexual behavior.

Animals↗
PubMed1975

Copulatory behavior of golden hamsters: effects on pregnancy.

Two experiments were conducted to study the role of male copulatory behavior in initiating physiological responses necessary for pregnancy in female hamsters. In Experiment 1, it was found that copulation beyond the first ejaculatory series is critical to attainment of maximal probabilities of pregnancy. Whereas all females became pregnant when mated to a criterion of sexual satiety, only 20 percent were pregnant after one ejaculatory series. The relationship between increased copulatory stimulation and increased probability of pregnancy was further refined in Experiment 2. Females required more than 4 ejaculatory series to maximize the probability of pregnancy. Mounts without intromission had no effect. Neither parturition number of ova shed, nor little size appeared affected by amount of copulatory stimulation. A coadaptation between the copulatory pattern of the males and the response systems of the females of several rodent species appears to have evolved and to aid successful reproduction.

Animals↗
PubMed1976

Effects of variations in copulatory behavior on pregnancy in two species of Peromyscus.

Stimulation requirements for the initiation of pregnancy were studied in cotton mice, Peromyscus gossypinus, and white-footed mice, P. leucopus. Mating to satiety rather than for one ejaculatory series significantly increased the per cent of P. gossypinus females pregnant (63% vs 0%). Among females mated to satiety, those which became pregnant received significantly more copulations than those which did not. While no P. leucopus female mated for one ejaculatory series became pregnant, the increase in the probability of pregnancy following tests continued to satiety (or satiety plus overnight) was not significant, as just 20% of females in the satiety groups became pregnant. The multiple ejaculation pattern in these species appears to be an integral part of pregnancy initiation.

Animals↗
PubMed1982

Age differences in Copulatory behavior and serum 17 beta-estradiol in female rhesus monkeys.

Young, sexually mature female rhesus monkeys housed in outdoor groups have been found to exhibit significantly longer mating periods associated with first conception compared with the duration of the annual period exhibited by older, multiparous females. An analysis of the sexual behavior and corresponding serum concentration of 17 beta-estradiol (E2) a progesterone, (P) in two age groups of rhesus females revealed that young females copulated on significantly more days prior to the E2, ovulatory peak than did older females. Serum concentrations of E2 were significantly higher from -30 to Day- 10 prior to the E2 peak (Day 0) in young females. Estradiol concentrations were similar for both age groups during the remaining follicular and periovulatory period. No age differences in serum P were observed between the two groups. Serum E2 levels associated with the onset of mating were similar in the two age groups with levels rising from 73.5 +/- 4.0 pg/ml prior to mating to 97.2 +/- 4.6 pg/ml. Thus the hormonal profile associated with the onset of mating is similar for both age groups, and the earlier occurrence of mating behavior prior to ovulation in young females is accounted for by an earlier rise in serum E2.

Aging↗
PubMed1982

Effects of medroxyprogesterone acetate on socio-sexual behavior of stumptail macaques.

Two studies assessed (1) the effect of medroxyprogesterone acetate (MPA), Depo-Provera, on socio-sexual behaviors, and (2) the interaction between socio-environmental conditions and MPA treatment effects. Study One utilized two males and eight female members of a semi-free-ranging island colony. Females received 30 or 100 MPA IM or were untreated. Study Two used three laboratory-housed pairs of tubal-ligated females, observed during 30 min behavior tests with one of three males. Sexually preferred females received 30 mg MPA IM. Semi-free-ranging treated females received fewer ejaculations than untreated females and did not copulate for up to 68 days post-treatment. Rates of grooming were not affected. In the laboratory tests, mean rates of ejaculations per test were reduced for treated females but increased for untreated females, and untreated females groomed males more than did treated females. Contrary to previous studies, these results suggest that stumptail macaque sexual behavior can be influenced by hormones but this influence is modulated by socio-environmental factors.

Animals↗
PubMed1983

Penile reflexes in intact rats following anesthetization of the penis and ejaculation.

Application of the topical anesthetic pontocaine (tetracaine hydrochloride) to the penis and preputial sheath virtually abolished the display of penile reflexes by intact rats. When pontocaine was applied immediately following ejaculation in copula, however, normal genital reflexes were observed in the majority of rats, albeit with a prolonged latency to the first erection relative to the control test. These same animals were, nonetheless, unable to achieve intromission when returned to the mating arena despite repeated mounting attempts. These data suggest that sensory input to the genitalia is generally necessary for the display of penile reflexes in the rat. However, stimuli associated with copulation can override the suppressive effect of sensory loss of these reflexes, presumably due to removal of supraspinal inhibition.

Animals↗
PubMed1984

Sexual play and its functional significance in the domestic sheep (Ovis aries L.).

All the patterns of male sexual behavior were present from the first week of age in male and female lambs. The frequency of this sexual play increased considerably during the first month of life, and returned to a low level until early puberty. These behavioral changes could not be correlated with any hormonal changes. Rearing the lambs in the absence of adult females, in all-male groups or in physical isolation until weaning at 3 months of age, was without consequence for adult sexual behavior. However, despite the low level of sexual-like interactions during the pre and early pubertal period, i.e., between 3 and 6 months of age, the sexual segregation had a clear adverse effect on the development of the copulatory activity: the occurrence of the first copulation was delayed. However, after the first mating, the level of sexual activity was not affected by the treatment.

Aggression↗
PubMed1988

High dosage testosterone propionate induces copulatory behavior in the obese male Zucker rat.

Genetically obese male Zucker rats sire few litters compared with lean males. High dosage testosterone propionate (TP) dramatically improves their litter production. Here we report the effect of high dosage TP on the copulatory behavior of obese males. Subjects were placed with ovariectomized, hormonally-primed females 24 hr after receiving a subcutaneous injection of vehicle or 20 mg TP. Other obese males received three consecutive daily TP injections or TP once every three days for up to 30 days prior to being tested. While 90% of sham-injected lean males became sexually active, only 18.2% of sham-injected obese males did so. In contrast 50% to 62.5% of TP-injected obese males became active depending on TP exposure. The proportion of obese males which ejaculated was high for sham-injected males which copulated, but varied with TP exposure for TP-injected males. In other respects the copulatory performance of obese and lean males was similar. High dosage TP increases fertility by correcting a behavioral deficit. Three possible mechanisms of TP action are proposed.

Animals↗
PubMed1988

Retention of masculine sexual behavior following castration in male B6D2F1 mice.

The reduction of masculine sexual behavior following castration varies widely among genotypes. In contrast to the loss of sexual behavior by castrated males of other strains, males of the B6D2F1 genotype retain the ejaculatory reflex for many weeks after castration. The present study examined this retention phenomenon. Masculine sexual behaviors were measured before and after castration or sham operation in male C57BL/6J, DBA/2J, and B6D2F1 mice. Castrated C57BL/6J and DBA/2J males showed a rapid decline in copulatory behavior. In contrast, 30% of the B6D2F1 males continued to ejaculate 25 weeks after castration. Regardless of whether or not sexual behaviors were retained, levels of plasma testosterone and hypothalamic nuclear estrogen receptors were reduced by castration. These results suggest that the intra- and inter-strain differences in the retention of sexual behavior following castration are not due to differences in levels of steroid hormones. Further, some B6D2F1 males retain the ability to copulate in the absence of gonadal hormone levels required for the maintenance of sexual behavior in other genotypes.

Animals↗