Appetitive and Consummatory Sexual Behaviors of Female Rats in Bilevel Chambers: I. A Correlational and Factor Analysis and the Effects of Ovarian Hormones

This study investigated measures of sexual behavior displayed by female rats in bilevel chambers, the statistical relationships among the measures, and their dependency on hormone priming. Normative data from a standard 35-min test of sexual behavior were gathered from 82 fully primed sexually experienced Long-Evans females and subjected to multiple correlational and factor analyses. Several consummatory measures of copulation were related significantly, whereas appetitive level changing was statistically independent of consummatory measures. Factor analyses were conducted using orthogonal rotations of correlational matrices derived either from (a) measures of female behavior alone or (b) measures of female and male behavior together. The first analysis revealed five factors that accounted for 84% of the intersubject variance: Receptivity, Pacing, Appetitive Level Changing, Lordosis Reflex, and Solicitation. The second factor analysis with male data included revealed seven factors that accounted for 95% of the intersubject variance: Pacing, Copulatory Rate, Mount Count, Receptivity, Appetitive Level Changing, Solicitation, and Lordosis Reflex. Subsequently, subsets of these females were maintained on different steroid priming regimens (oil, low estrogen, high estrogen, high estrogen and progesterone) prior to a standard test of sexual behavior. Although the expression of all sexual behaviors required estrogen priming, appetitive level changing, solicitation, and pacing required progesterone for their full expression. Finally, appetitive level changing developed following hormone treatment alone, regardless of whether the females received access to sexually active males, inactive castrated males, or other females. Use of bilevel chambers allows complex patterns of sexual behavior to be observed in female rats and may thus facilitate the identification of neurochemical or endocrine mechanisms associated with different aspects of female sexual motivation and performance.     

Effects of the nonsteroidal aromatase inhibitor, Fadrozole, on sexual behavior in male rats.

The new nonsteroidal aromatase inhibitor, Fadrozole (CGS 16949A, CIBA-Geigy Corp.), was tested for its ability (i) to inhibit the conversion of testosterone (T) to estradiol (E2) in brain and (ii) to suppress male sexual activity. Sprague-Dawley rats were castrated and immediately given sc Silastic T-implants and osmotic minipumps delivering 2.5 mg/kg/day Fadrozole (N = 4), 0.25 mg/kg/day Fadrozole (N = 4), or water (N = 4 controls). T-implants were removed after 6 days and, 3 days later, 3H-T (1 microCi/g) was given as an iv bolus. No 3H-E2 was detected in hypothalamic or amygdaloid nuclear pellets from Fadrozole-treated males but this metabolite predominated in controls. However, nuclear concentrations of 3H-T and [3H]dihydrotestosterone were similar in all groups. In another group of males (N = 18), brain aromatase activity was reduced by more than 96% at the 0.25 mg/kg dose level. Additional castrated, T-implanted males received minipumps delivering 0.25 mg/kg/day Fadrozole (six males) or water (six behaviorally matched controls) and were tested weekly with receptive females. After 2 weeks, ejaculations were reduced by 77% compared with controls (P less than 0.01) and, after 4 weeks, intromissions were also significantly reduced (P less than 0.05) but less so (48%). Radioenzymatic estimates of plasma aromatase inhibitor levels remained elevated throughout Fadrozole treatment. These males were then given Silastic E2 implants: intromissions increased significantly in 1 week (P less than 0.01), but ejaculations remained below control values. Results supported the view that aromatization is important for sexual behavior in male rats and suggested that Fadrozole has utility for studying the mechanisms by which testosterone affects behavior.     

Conversion of testosterone to estradiol may not be necessary for the expression of mating behavior in male Syrian hamsters (Mesocricetus auratus)

Male sexual behavior is mediated in part by androgens, but in several species, mating is also influenced by estradiol formed locally in the brain by the aromatization of testosterone. The role of testosterone aromatization in the copulatory behavior of male Syrian hamsters is unclear because prior studies are equivocal. Therefore, the present study tested whether blocking the conversion of testosterone to estradiol would inhibit male hamster sexual behavior. Chronic systemic administration of the nonsteroidal aromatase inhibitor Fadrozole (2.0 mg/kg/day) for 5 or 8 weeks did not significantly increase mount latency or reduce mount frequency, intromission frequency, ejaculation frequency, or anogenital investigation relative to levels shown by surgical controls. However, Fadrozole effectively inhibited aromatase activity, as evidenced by the suppression of estrogen-dependent progesterone receptor immunoreactivity in the male hamster brain. The JZB39 anti-progesterone receptor antibody labeled significantly more neurons in brains of sham-treated hamsters than in brains of Fadrozole-treated hamsters. These data suggest that aromatization of testosterone to estradiol is not necessary for normal mating behavior in Syrian hamsters.     

Rapid effects of aromatase inhibition on male reproductive behaviors in Japanese quail

Non-genomic effects of steroid hormones on cell physiology have been reported in the brain. However, relatively little is known about the behavioral significance of these actions. Male sexual behavior is activated by testosterone partly through its conversion to estradiol via the enzyme aromatase in the preoptic area (POA). Brain aromatase activity (AA) changes rapidly which might in turn be important for the rapid regulation of behavior. Here, acute effects of Vorozole, an aromatase inhibitor, injected IP at different doses and times before testing (between 15 and 60 min), were assessed on male sexual behavior in quail. To limit the risk of committing both types of statistical errors (I and II), data of all experiments were entered into a meta-analysis. Vorozole significantly inhibited mount attempts (P < 0.05, size effect [g] = 0.527) and increased the latency to first copulation (P < 0.05, g = 0.251). The treatment had no effect on the other measures of copulatory behavior. Vorozole also inhibited appetitive sexual behavior measured by the social proximity response (P < 0.05, g = 0.534) or rhythmic cloacal sphincter movements (P < 0.001, g = 0.408). Behavioral inhibitions always reached a maximum at 30 min. Another aromatase inhibitor, androstatrienedione, induced a similar rapid inhibition of sphincter movements. Radioenzyme assays demonstrated that within 30 min Vorozole had reached the POA and completely blocked AA measured in homogenates. When added to the extracellular milieu, Vorozole also blocked within 5 min the AA in POA explants maintained in vitro. Together, these data demonstrate that aromatase inhibition rapidly decreases both consummatory and appetitive aspects of male sexual behavior.     

Appetitive and consummatory sexual behaviors of female rats in bilevel chambers. II. Patterns of estrus termination following vaginocervical stimulation

Copulation with intromission or manual vaginocervical stimulation (VCS) shortens the duration that intact female rats maintain lordosis responding during estrus. The present study examined whether VCS could shorten the duration of both appetitive and consummatory measures of female sexual behavior, and whether these effects occur differentially in time and across different hormone priming intervals. Ovariectomized, sexually experienced female rats were administered subcutaneous injections of estradiol benzoate 48 h and progesterone 4 h, before receiving 50 manual VCSs with a lubricated glass rod distributed over 1 h. Control females received sham VCSs distributed over the same time. The females were then tested for sexual behavior in bilevel chambers with two sexually vigorous males (to one ejaculatory series or 10 min with each male, separated by 5 min) 12, 16, and 20 h after VCS. Prior to the final hormone treatment, different groups of females had been given the same hormone treatment either 28, 14, 7, or 4 days before. In females tested at 28- and 14-day hormone intervals, VCS induced both active and passive rejection responses at 12, 16, and 20 h. In contrast, females that received sham VCS displayed relatively normal sexual behavior at 12 h, although by 16 and 20 h these females displayed active and passive rejection. Females tested at 7- or 4-day intervals displayed normal levels of lordosis at all testing times, regardless of VCS treatment. These data indicate that VCS facilitates rejection responses that precede the decrease in lordosis responsiveness. However, the effects of VCS are dependent on the frequency of hormone priming, suggesting that hormone treatment may block some of the long-term inhibitory effects of VCS on female sexual behavior.     

Aromatization and androgen stimulation of sexual behavior in male and female rats

6α-Fluorotestosterone, an androgen that is not aromatized in a standard assay system, stimulated sexual behavior in both male and female rats. In males, it was as effective as testosterone. 19-Nortestosterone also stimulated more male sexual behavior than would be expected on the basis of its aromatizability in standard assays. In other tests of the aromatization hypo we used the anti-estrogen, CI-628. This drug inhibited androgen-induced sexual receptivity in female rats, but did not inhibit androgen-induced sexual behavior in male rats. In females, CI-628 antagonized testosterone and 6α-fluorotestosterone equally. These data suggest that the structures of androgens, rather than their abilities to be aromatized, determine behavioral effectiveness.     

Effects of ovarian hormones on the behavior of captive Macaca fascicularis

To examine the effects of ovarian hormones on the behavior of female Macaca fascicularis and their male partners, daily 1-hr behavior tests were conducted while ovariectomized females were (1) untreated, (2) given estradiol benzoate (EB) (5 μg subcutaneously [s.c.]/day), (3) given estradiol benzoate together with increasing doses of progesterone (P) (5 mg, 10 mg, and 20 mg. s.c./day), and (4) given testosterone propionate (TP) (0.25 mg s.c./day) (six pairs, 540 tests). Weekly blood samples were analyzed by radioimmunoassay for plasma hormone levels (81 samples). Estrogen treatment produced plasma estradiol levels similar to those of intact females during the late follicular phase of the menstrual cycle. Additional progesterone at the lowest dose produced plasma progesterone levels similar to or somewhat higher than those during the midluteal phase, while higher doses produced supraphysiological levels. Androgen treatment resulted in plasma levels well above the physiological range. Hormone treatments produced highly significant effects on the sexual, social, and aggressive interactions of the pairs. As in rhesus monkeys, estrogen increased male and female sexual activity, and increasing doses of additional progesterone reversed these effects. Unlike in rhesus monkeys, testosterone propionate increased both female sexual motivation (invitations) and also male sexual activity and ejaculatory performance. The direction of the hormone-dependent changes in grooming and aggressive interactions confirmed earlier results with intact females and indicated that aggressive interactions and male grooming times were highest, and female grooming times were lowest, when copulatory activity was at its height.     

Aromatase inhibition blocks the expression of sexually-motivated cloacal gland movements in male quail

In Japanese quail (Coturnix japonica), activation of appetitive and consummatory aspects of male sexual behavior requires aromatization of testosterone (T) into estrogens. Appetitive male sexual behavior (ASB) is usually assessed with the use of a learned social proximity procedure. In the present experiment, we investigated the role of estrogens in the activation of an another index of ASB, the female-induced activation of rhythmic cloacal sphincter movements (RCSMs) that are produced in reaction to the visual presentation of a female. Consummatory sexual behavior (CSB) was also assessed by the frequency and latency of copulatory behaviors. Castrated male quail were treated with Silastic implants filled with T in association with chronic injections of the aromatase inhibitor Vorozole (R83842; 1mg/kg twice a day; CX + T + VOR group). Control birds were implanted with T capsules only (CX + T group). CSB was almost completely blocked by injections of the aromatase inhibitor. The RCSM frequency decreased progressively in the CX + T + VOR group by comparison with the CX + T group and was therefore significantly reduced at the end of the experiment. These results demonstrate that the frequency of RCSM, a second measure of ASB is, like the social proximity response and CSB, blocked by inhibition of estrogen production. It was shown previously that lesions of the preoptic area inhibit both aspects of the appetitive sexual behavior (proximity response and RCSM). It is therefore, likely that both responses are controlled, like copulation, by aromatase-containing neurons of the preoptic area.     

Homotypical sexual behavior in gonadectomized female and male rats treated with 5α-19-hydroxytestosterone: Comparison with related androgens

Ovariectomized female rats were treated in turn over several weeks with estradiol benzoate (EB), testosterone (T), 19-hydroxytestosterone (19HT), dihydrotestosterone (DHT) and 5α-19-hydroxytestosterone (5α19HT). EB was given as a single dose, the androgens were given over 3 days, and progesterone (P) was given 48 hr after the last injection. Each week, rats were tested for lordosis behavior 4–6 hr after P. High levels of receptivity were seen after EB + P, 19HT + P and T + P. Rats treated with DHT + P or 5α19HT + P were unreceptive. Four groups of castrated male rats were treated with T, 19HT, DHT and 5α19HT for 4 weeks starting from castration. In weekly sexual behavior tests, only T and 19HT maintained normal copulatory performance throughout the experiment. 19HT and 5α19HT had negligible effects on peripheral androgen target organs. The failure of 5α19HT to stimulate sexual behavior in rats of either sex supports the view that this steroid does not undergo central aromatization.     

Some contrasting effects of surgical and “chemical” castration on the behavior of male cynomolgus monkeys (Macaca fascicularis)

In nonhuman primates, surgical castration reduces plasma testosterone levels and male sexual behavior, and testosterone replacement restores them. Chemical castration with compounds that lower plasma testosterone levels is used clinically in the treatment of certain forms of cancer and to reduce aberrant sexual behavior in male sex offenders. In the United States, medroxyprogesterone acetate (MPA) is the drug most used to help reduce serious sexual behavioral problems in men. We were therefore interested in comparing the behavioral effects of MPA treatment (40 mg once a week) in 4 intact male cynomolgus monkeys (4 pairs, 120 tests) with data from an earlier study in our laboratory on 4 males observed before and after surgical castration (16 pairs, 192 tests). Both MPA treatment and surgical castration reduced plasma testosterone to very low levels and decreased ejaculatory activity, but MPA treatment additionally affected measures of male sexual motivation (decreased numbers of male mounting attempts and increased mounting attempt latencies) which were not primarily affected by surgical astration. However, surgical castration decreased intromission ability (percentage of intromitted thrusts per test) and male yawning behavior more rapidly than did MPA treatment. This suggested a hypothesis that different mechanisms could be involved in the behavioral effects—namely, that surgical castration may act primarily via testosterone-dependent peripheral mechanisms, while chemical castration with MPA does so primarily via central mechanisms regulating sexual motivation.     

Pre- and postnatal bisphenol A treatment results in persistent deficits in the sexual behavior of male rats, but not female rats, in adulthood

Perinatal administration of the endocrine disruptor bisphenol A (BPA) reportedly inhibits the sexual behavior of sexually naïve adult male rats. In order to evaluate the effects of BPA administration during early development on later reproductive behavior, we administered one of five doses of bisphenol A daily to pregnant female rats throughout gestation and lactation, and quantified the appetitive and consummatory sexual behaviors of the resultant male and female offspring over multiple sexual encounters in adulthood. Males receiving low dose perinatal BPA (50 μg/kg bw/day) showed persistent deficits in sexual behavior in adulthood. Males receiving the highest dose (5 mg/kg bw/day), however, were indistinguishable from controls with respect to consummatory sexual behaviors but showed decreased latencies to engage in those behaviors when sexually naïve, with significant non-linear, or U-shaped, dose-response relationships observed on the first and last day of testing. Adult female sexual behavior was not affected by early BPA administration at any dose tested. These results are consistent with previous reports that BPA exerts behavioral effects especially at low doses, and further indicates that BPA can cause lasting impairment of sexual behavior in males, but does not alter the normal development of female appetitive or consummatory sexual behaviors. To our knowledge, this is the first report indicating that adult sexual performance is impaired in sexually experienced animals following perinatal exposure to bisphenol A.     

Adult partner preference and sexual behavior of male rats affected by perinatal endocrine manipulations

Intact adult male rats, in which aromatization of testosterone to estradiol was prevented pre- and/or neonatally by ATD (1,4,6-androstatriene-3,17-dione), were repeatedly tested for partner preference behavior (choice: estrous female vs active male). In consecutive tests increasing preference scores for the female were found. Neonatal ATD males showed significantly lower preference scores for an estrous female than controls or prenatal ATD males. Prenatal ATD caused preference scores only slightly lower than those of controls. Ejaculation frequencies were markedly reduced or even absent in neonatal ATD males. Prenatal ATD treatment only had no or a moderately lowering effect on ejaculation frequency. Lordosis behavior of adult intact males was more facilitated following neonatal ATD treatment than following prenatal ATD treatment. In a number of tests the serotonergic drug 8-OH-DPAT was injected prior to testing for sexual partner preference and copulatory behavior. DPAT significantly increased preference for an estrous female in all groups of males when interaction was possible, but had no effect when sexual interaction was prevented by wire mesh. DPAT was able to increase the number of ejaculators in nonejaculating groups (i.e., perinatally ATD-treated males). "Premature ejaculations," i.e., ejaculations with the first intromission, were frequently observed with DPAT treatment in all groups of males. In conclusion, the availability of neonatal estrogen (derived from testosterone) organizes, at least partially, the preference for an estrous female normally shown by adult male rats. The lack of neonatal estrogen causes males to be less masculinized, both in partner preference behavior and ejaculatory behavior, and less defeminized in lordosis behavior.(ABSTRACT TRUNCATED AT 250 WORDS)     

Administration of an oxytocin receptor antagonist attenuates sexual motivation in male rats

In male rats, oxytocin impacts both sexual arousal and certain types of consummatory sexual behaviors. However, the role of oxytocin in the motivational aspects of sexual behavior has received limited attention. Given the role that oxytocin signaling plays in consummatory sexual behaviors, it was hypothesized that pharmacological attenuation of oxytocin signaling would reduce sexual motivation in male rats. Sexually experienced Long-Evans male rats were administered either an oxytocin receptor antagonist (L368,899 hydrochloride; 1 mg/kg) or vehicle control into the intraperitoneal cavity 40 min prior to placement into the center chamber of a three-chambered arena designed to assess sexual motivation. During the 20-minute test, a sexually experienced stimulus male rat and a sexually receptive stimulus female rat were separately confined to smaller chambers that were attached to the larger end chambers of the arena. However, physical contact between test and stimulus rats was prevented by perforated dividers. Immediately following the sexual motivation test, test male rats were placed with a sexually receptive female to examine consummatory sexual behaviors. Although both drug and vehicle treated rats exhibited a preference for the female, treatment with an oxytocin receptor antagonist decreased the amount of time spent with the female. There were no differences between drug and vehicle treated rats in either general activity, exploratory behaviors, the amount of time spent near the stimulus male rat, or consummatory sexual behaviors. Extending previous findings, these results indicate that oxytocin receptors are involved in sexual motivation in male rats.     

Lesions to the Medial Preoptic Area Affect Singing in the Male European Starling (Sturnus vulgaris)

The aromatization of testosterone (T) in the medial preoptic nucleus (POM) is known to regulate male courtship and sexual behaviors expressed prior to, and in anticipation of, copulation. Singing in male European starlings is used to attract mates prior to physical sexual contact, suggesting that the POM might be involved. The present study was performed to examine the effects of lesions targeting the POM on singing and courtship behavior in reproductively active male starlings. A significant decrease in song output and the gathering of green nest materials was observed in males with lesions to the POM compared to males with damage to brain areas outside of the POM. Lesions did not affect a male's tendency to remain near a female or to occupy a nestbox, suggesting that the effects of POM lesions were specific to courtship behaviors. Behavioral differences were not related to testis mass or volume, and GnRH immunoreactivity was observed within the hypothalamus and median eminence for each male, suggesting that the effects of POM lesions were related specifically to POM involvement in song expression rather than to a disruption of the GnRH axis. These results suggest a general role for the POM in the expression of behaviors related to sexual arousal or anticipation, including song.     

Glutamate release in the ventromedial hypothalamus of the female rat during copulation: Modulation by estradiol

Binding of glutamate or its ionotropic receptor agonists in the ventromedial hypothalamus (VMH) of female rats inhibits both appetitive and consummatory aspects of sexual behavior. Because vaginocervical stimulation activates glutamate neurons in the VMH, and administration of estradiol benzoate (EB) and progesterone (P) delays this effect, the present study examined the effects of hormonal priming on glutamate release within the VMH of female rats paired with sexually vigorous males. Ovariectomized, sexually experienced rats were implanted with guide cannula aimed at the ventrolateral VMH, through which microdialysis probes were inserted prior to testing. Females were assigned randomly to one of three hormone treatment conditions: EB + P, EB alone, or the oil vehicle. Testing was conducted over 5 h, including a 120-min period of habituation to the testing chamber, a 60-min period of baseline sample collection, and a 120-min period during which a sexually vigorous male was introduced into the testing chamber. Dialysates were collected every 20 min during the test and were analyzed for glutamate using HPLC. Females primed with oil had large and significant increases in glutamate release from baseline once the male was introduced to the chamber. Treatment with EB alone decreased glutamate release in response to male cues. Although treatment with EB + P did not differ significantly from EB alone, the degree of reduced glutamate release was less than with EB alone. These results indicate that priming with EB reduces glutamate transmission in the VMH in response to male cues. Taken together with our previous findings, estradiol blunts the activation of glutamate neurons in the VMH thus allowing female rats to copulate.     

Testosterone modulation of reproductive indices vs. morphine antinociception in male rats

The purpose of this study was to determine whether testosterone (T) concurrently modulates reproductive and nociceptive systems in the adult male. Male Sprague-Dawley rats were orchidectomized, and then 28 days later implanted with capsules containing T or nothing (blanks). After 2, 7, 14 or 28 days' exposure to T-filled or blank capsules, rats were tested for male sexual and nociceptive behaviors in a counter-balanced design. As the duration of T exposure lengthened, the percentage of rats showing male sexual behaviors and the weights of steroid-sensitive organs systematically increased, and latencies to show sexual behaviors decreased. T treatment did not affect basal nociception on either the hotplate or tail withdrawal tests, but significantly increased morphine's antinociceptive potency on the tail withdrawal test -- however, this effect was small, and independent of duration of T exposure. Thus, T treatment that altered male sexual behavior and reproductive physiology in a systematic, duration-dependent manner did not similarly alter basal nociception or morphine antinociception. These findings suggest that in adult male rats, although T may modulate both male sexual behaviors and opioid antinociceptive sensitivity, these T effects do not occur in concert.     

Previous sexual experience alters the display of paced mating behavior in female rats

The present study tested whether the display of paced mating behavior in female rats over four weekly tests is affected by sexual experience and whether test parameters, i.e., ending the test based on time or number of stimulations received, influence behavioral changes. In Experiment 1A rats with nonpaced sexual experience returned to the male more quickly overall compared to sexually naïve rats in a 30-min test of paced mating behavior. In Experiment 1B, rats received four weekly 30-min tests with one, different, male rat partner each week. Over the four tests, rats returned to the male significantly more quickly after intromissions, but significantly more slowly after ejaculations. Experiment 2A tested whether sexual experience would influence paced mating behavior in tests with a 15-intromission end criterion and the male replaced after ejaculation. Rats tested weekly under 15-intromission test conditions returned to the male significantly more quickly after intromissions, but no behavioral change was observed after ejaculations. When those same rats were given a 30-min test of paced mating behavior (Experiment 2B), they returned to the male significantly more slowly after ejaculations. Collectively, these data show that sexual experience influences the display of paced mating behavior in female rats and that the test parameters interact with sexual experience to influence the nature of the changes. Sexual experience may facilitate behaviors that promote reproductive success in female rats.     

Persistence of sexual behavior in ovariectomized stumptail macaques following dexamethasone treatment or adrenalectomy

Daily administration over a period of 6 weeks of increasing doses of dexamethasone sodium phosphate (DEX) to seven long-term ovariectomized female stumptail monkeys significantly lowered circulating levels of testosterone without reducing any aspect of the females' sexual behavior or that of their male partners. Since treatment with DEX failed to suppress serum testosterone levels completely an additional experiment was performed in which the sexual behavior of five ovariectomized stumptails was compared before and after bilateral adrenalectomy, combined with chronic administration of both gluco- and mineralocorticoids. Serum levels of both testosterone and estradiol were reduced to very low levels in females after ovariectomy and adrenalectomy, yet no significant depression of females' sexual performance or that of their male partners occurred. Subsequent sc administration of estradiol or estradiol + testosterone in Silastic capsules to ovariectomized, adrenalectomized stumptails had little effect on sexual interaction. In a third experiment five ovariectomized stumptails which initially were relatively unreceptive and unattractive to males were given first testosterone and then testosterone + estradiol sc in Silastic capsules. One of the three indexes of females' receptivity increased significantly after testosterone; however, no other essential aspect of sexual interaction was affected. These findings suggest that sex steroids are normally not required in the female stumptail macaque for activation of preceptive and receptive sexual behaviors or for maintenance of sexual attractivity.     

Neonatal hormonal influences on the development of proceptive and receptive feminine sexual behavior in rats

The objective of this study was to examine the influence of androgen and of the inhibiting of aromatization of androgen to estrogen during the early neonatal period on the development of receptive (lordosis and acceptance of stimulus male mounting attempts) and proceptive (affiliation with and solicitation of stimulus males) feminine sexual behavior. Within 8 hr of birth, male rats were castrated or received subcutaneous implants of the aromatase inhibitor androst-1,4,6-triene-3, 17-dione (ATD) while females received injections of testosterone propionate (TP). At 90 days of age all treated animals and controls were tested for receptive and proceptive feminine sexual behavior. It was found that androgen present neonatally blocked proceptive as well as receptive behavior patterns in adult rats. The proceptive and receptive feminine sexual behavior patterns displayed by adult males deprived of the effects of androgen neonatally either by castration or by treatment with ATD were comparable to those of normal females.