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At least 91 records · Page 5Linked to original sources
PubMed1977

Portions of the central nervous system controlling reproductive behavior in Drosophila melanogaster.

Drosophila melanogaster sex mosaics were tested in their courtship interactions with females and then with males. The distribution of genetically male and female tissues in each mosaic was determined with respect to an external cuticle marker and an internal enzyme marker. Performance of malelike courtship was correlated with the genotype of various tissues, with special attention being paid to the genotypes of head and thoracic ganglia. Male tissue in the left or right dorsal brain is necessary and nearly always sufficient to trigger early courtship actions--following of females and wing extension at them--but male tissue in both the dorsal brain and thoracic ganglia is necessary for attempted copulation to occur. Female tissue on or in the abdomen is nearly always necessary and sufficient for a mosaic to be courted by a male.

Animals↗
PubMed1987

Central and peripheral metabolism of 5 alpha-dihydrotestosterone in the male Japanese quail: biochemical characterization and relationship with reproductive behavior.

An in vitro radioenzymatic assay and purification procedure by thin-layer chromatography were used to study the metabolism of dihydrotestosterone (DHT) into 3 alpha- and 3 beta-androstanediols by the brain and cloacal gland of Japanese quail. Kinetic studies showed that these 2 metabolites are produced in a linear fashion with respect to time of incubation for up to 15 min but that they continue to accumulate for up to 4 h. The maximum velocity of these reactions is high (nmol/mg protein/15 min), but the affinities of the enzymes for DHT are low (in the microM range). The enzymatic activities are not evenly distributed in the brain: they are high in the tuberal hypothalamus and lobus parolfactorius but low in the preoptic area and anterior hypothalamus. Enzyme activities are not markedly affected by treatment of the birds with either testosterone or DHT. The activity of these enzymes is lower in the preoptic area and tuberal hypothalamus of DHT-treated birds which display female-directed sexual behavior than in the same brain areas of birds which are sexually inactive. We discuss the relationships between this reductive metabolism of DHT and the activational effects of the steroid on sexual behavior.

Androstane-3,17-diol↗
PubMed1988

Bethanechol-induced increase in hypothalamic estrogen receptor binding in female rats is related to capacity for estrogen-dependent reproductive behavior.

Neuroactive agents associated with different neurotransmitter systems can modulate the number of hypothalamic estrogen binding sites. It has been demonstrated previously that the muscarinic cholinergic agonist, bethanechol, administered 30 min prior to in vitro estrogen receptor assays increases the concentration of hypothalamic estrogen binding sites by 30-35% in female rats. Bethanechol was without effect on male hypothalamic preparations. In order to investigate further this sex difference and in an attempt to determine a relationship between the modulation of estrogen binding sites and a sexually differentiated function, bethanechol was given to female rats rendered either anovulatory and capable of displaying lordosis or anovulatory and behaviorally insensitive to estrogen. The results showed that bethanechol significantly increased the number of estrogen binding sites in females capable of displaying lordosis but not in females which did not show this estrogen-dependent behavior. It is possible that the capacity for drug-induced modulation of estrogen binding sites could be related functionally to the ability to display lordosis behavior.

Animals↗
PubMed1989

Central implants of diluted estradiol: independent effects on ingestive and reproductive behaviors of ovariectomized rats.

The present experiment was undertaken to evaluate the hypothesis that the effects of estrogens on feeding and sexual behaviors are organized separately within the brain. Thirty-three ovariectomized rats were implanted with bilateral guide cannulae aimed at either the paraventricular nucleus (PVN), medial preoptic area (MPOA), or posterior hypothalamus (PH). Subjects that received PVN implants were stimulated with either undiluted estradiol, a 3:1, or 10:1 mixture of cholesterol and estradiol. Animals in the other groups were treated with undiluted estradiol. All females were stimulated unilaterally with cholesterol and estradiol, yielding a total of 66 stimulation sites. Histological analysis revealed that, compared to cholesterol implants, undiluted estradiol in the PVN reduced food intake and body weight. More importantly, diluted estradiol implants in the PVN significantly lowered food intake and body weight. In contrast, undiluted estradiol in the MPOA, PH, or ventromedial hypothalamus (VMH) had no significant effects on feeding or body weight. Analyses of variance revealed significant main effects of implant location on female sexual behavior. Newman-Keuls tests indicated that diluted estradiol implants in the PVN produced lordosis quotients and quality scores that were significantly lower than those obtained with VMH implants. The possibility that the behavioral changes observed were due to peripheral rather than central effects of the hormone was evaluated by comparing the results of implants that produced vaginal cell cornification to those that did not. There were no significant differences between these groups on any of the other dependent variables, indicating that peripheral estradiol sufficient to induce vaginal cell cornification was neither necessary nor sufficient to account for the behavioral changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Progestins affect reproductive behavior and androgen receptor dynamics in male guinea pig brain.

The present study extends previous studies of ours by comparing the anti-androgenic effect of a progestin agonist (R5020) with progesterone (P). Intact male guinea pigs treated with P (1 and 10 mg/day) and R5020 (100 micrograms/day) had greater latency to mount and lower numbers of mounts and intromissions compared to controls. Ejaculation and plasma testosterone concentration were not affected. Specific brain regions were analyzed for androgen receptor (AR) content. Progestins produced fewer (P less than 0.01) nuclear AR in hypothalamus-preoptic area and pituitary without associated changes in cytosolic AR. These data are best interpreted by postulating an effect of P on AR dynamics mediated through the P receptor and not by competition for androgen binding to its receptor.

Animals↗
PubMed1992

A peptidergic circuit for reproductive behavior.

A projection from the medial amygdaloid nucleus to the hippocampus and septum probably uses vasopressin as a transmitter. The nucleus synthesizes vasopressin and activation of the nucleus has a hippocampal effect that is completely blocked by a vasopressin antagonist. The afferent and efferent projections of this peptidergic nucleus suggest a possible role for the system in sexual behavior. Stimulation of the nucleus inhibits the output of the hippocampus in both genders and reorganizes behavior for a period of 15-20 min. In males, the effect of peptidergic activation is to produce a behavior that resembles the post-ejaculatory interval in coitus. This state is characterized by an EEG that resembles slow-wave sleep and by ultrasonic vocalizations at a characteristic frequency of 22 kHz. Castration in either gender causes depletion of the peptide from the target fields and eliminates the peptidergic signal in the hippocampus after about 15 weeks. The effects of castration in males can be reversed by testosterone replacement. The fluctuation of estrogen levels in rat plasma during the estrus cycle happens too quickly to impact the peptidergic system, and thus there is no significant change in the strength of the peptidergic signal among the proestrus, estrus, metestrus and diestrus stages. This fact permits study of the physiology of the system without concern for stage of estrus but does not permit conclusions regarding its function in females.

Amygdala↗
PubMed1989

Sexual differentiation of reproductive behavior in pigs: defeminizing effects of prepubertal estradiol.

The present study sought to determine (1) whether estrogen by itself can defeminize the behavior of pigs during the late juvenile-early pubertal period, and (2) whether the progressive late defeminization reported for pigs is a true organizational effect, as opposed to an artifact of the time between castration and testing. Male pigs were castrated at 19-22 days or left intact and females were ovariectomized at 3 months. Additional males castrated at 19-22 days and females ovariectomized at 3 months were implanted with estradiol benzoate (EB) from 3 to 5.5 months. After castration of the previously intact males at the age of 5.5 months, all subjects were tested beginning at 6.5 months for proceptivity (choice of a male versus a female in a T-maze) and receptivity (immobilization to a mounting male) following an injection of EB. EB administered during development significantly defeminized proceptivity and receptivity in both sexes. The decrease in proceptivity was more pronounced in males than in females and was more pronounced than the decrease in receptivity, as if differentiation ends earlier for proceptivity than for receptivity; the decrease in receptivity was more pronounced in females. To see whether the capacity to display female-typical behavior is a function of time since castration, we castrated additional males at 4 months and tested for receptivity 9 days later following an injection of EB, then tested again with the other subjects at 6.5 months. The proceptivity and receptivity scores for males castrated at 4 months fell between those for intact males and males castrated at 3 weeks, and thus these animals were not completely defeminized. They were more receptive at 6.5 months than at 4 months, but the difference was not significant. These results indicate that in pigs estradiol defeminizes both receptive and proceptive behavior and that this defeminization can occur relatively late in development.

Animals↗
PubMed1989

Reproductive behavior and LH levels of cockatiels (Nymphicus hollandicus) associated with photostimulation, nest-box presentation, and degree of mate access.

To determine the relative contribution of mate access and environmental cues in stimulating egg-laying and plasma luteinizing hormone (LH) secretion in cockatiels (Nymphicus hollandicus), and of mate access on nest-inspection and bowl-formation, mated pairs were permitted different degrees of mate access (full contact, auditory plus visual contact, auditory contact only, or no contact) and sequentially exposed to three environmental conditions (8L:16D without nest-box access for 6 weeks; 15L:9D without nest-box access for 3 weeks; 15L:9D with nest-box access for 3 weeks). The results indicate that a high degree of mate access is essential for the performance of nesting behaviors, since birds allowed no mate access or only auditory mate access were significantly less likely to inspect the nest or form a nest-bowl. Furthermore, pairs permitted no contact, auditory contact only, or auditory and visual contact delayed nest-inspection and bowl-formation and were significantly less likely to lay eggs than pairs with total mate contact. LH levels were significantly elevated only in photostimulated females of pairs of permitted full mate and nest-box access. These results suggest that maximal sexual activity in cockatiels requires an array of behavioral and environmental cues and that a linear relationship exists between extent of social cues and sexual activity.

Animals↗
PubMed1987

Nonaromatizable androgens may stimulate a male mouse reproductive behavior by binding estrogen receptors.

Castrated DBA/2J male mice emitted 70 kHz vocalizations to female stimuli in response to 10 days of treatment with either testosterone (T, 300 micrograms/day), diethylstilbestrol (DES, 1 or 3 micrograms/day) or methyltrienolone (R1881, 900 micrograms/day). Lower dosages of R1881 (300 and 600 micrograms/day) and the oil vehicle were relatively ineffective in restoring vocalizations. The effects of these hormones on restoring seminal vesicle weight did not always parallel their effects upon behavior. In general T and R1881 (600 and 900 micrograms/day) were effective in restoring seminal vesicles while DES, the lowest dose of R1881 (300 micrograms/day), and the oil vehicle were ineffective. In receptor competition studies, R1881 pretreatment significantly reduced estrogen binding in hypothalamic-preoptic cytosol. In fact the most effective dose for restoring vocalizations (900 micrograms/day) reduced available estrogen binding sites by 91%. We propose that the male-typical vocalizations of mice may normally be stimulated through the activation of estrogen receptors following androgen aromatization and that the ability of a pharmacological dosage of R1881 (900 micrograms/day) to restore behavior may be due to interaction with estrogen receptors in the brain.

Androgens↗