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PubMed2001

Effects of humidity on reproductive behavior in male and female zebra finches (Taeniopygia guttata).

Zebra finches (Taeniopygia guttata) are regarded as opportunistic breeders with reproductive behaviors mediated by short-term proximal environmental conditions. This article provides experimental evidence for the role of humidity in reproductive behaviors. Zebra finches were subjected to experimentally manipulated high levels of relative humidity. Males gathered more nest material and sang more. Females showed no relationship between humidity and gathering nest materials, egg laying, or changes in rates of vocalization.

Animals↗
PubMed2001

Progesterone blockade of estrogen activation of mu-opioid receptors regulates reproductive behavior.

The mu-opioid receptor (MOR), a G-protein-coupled receptor, is internalized after endogenous agonist binding. Although receptor activation and internalization are separate events, internalization is a good assay for activation because endogenous opioid peptides all induce internalization. Estrogen treatment of ovariectomized rats induces MOR internalization, providing a neurochemical signature of estrogen activation of the medial preoptic nucleus. MOR activation appears to be the mechanism via which estrogen acts in the medial preoptic area to prevent the display of female reproductive behavior during the first 20-24 hr after estrogen treatment. Naltrexone, an alkaloid universal opioid receptor antagonist, prevented MOR internalization, suggesting that estrogen induces the release of endogenous opioid peptides that in turn activate the MOR. Enkephalins and beta-endorphin are nonselective endogenous MOR ligands. The most selective endogenous MOR ligands are the endomorphins. Infusions of selective MOR agonists, H-Tyr-d-Ala-Gly-N-Met-Phe-glycinol-enkephalin (DAMGO) or endomorphin-1, into the medial preoptic nucleus attenuated lordosis, and their effects were blocked with the MOR antagonist H-d-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP). Infusion of endomorphin-1 internalized MOR. To determine whether progestin also acts via the MOR system to facilitate reproductive behavior, ovariectomized rats were primed with 17beta-estradiol and progesterone. Progestin facilitation of lordosis was correlated with a reduction of estrogen-induced MOR internalization. Progestin reversed estrogen-induced MOR internalization, suggesting that progesterone blocked estrogen-induced endogenous opioid release, relieving estrogen inhibition and facilitating lordosis. These results indicate a central role of MOR in the mediation of sex steroid activation of the CNS to regulate female reproductive behavior.

Analgesics, Opioid↗
PubMed1993

Changes in plasma androgen levels associated with changes in male reproductive behavior in a brood cycling marine fish.

Like many paternal-caring fishes, male garibaldi (Hypsypops rubicundus) exhibit changes in reproductive behavior during the course of a brood cycle. The purpose of this study was to compare plasma levels of testosterone and 11-ketotestosterone among males in different phases of the brood cycle. These phases are characterized by differences in male courtship, nest maintenance, and egg fanning behavior. Blood samples were taken from wild-caught males, and plasma androgen levels were measured using radioimmunoassay techniques. Androgen levels among males in different phases of the brood cycle were concordant with differences in courtship behavior and also showed a general, positive correspondence with nest maintenance behavior. Levels were nearly inversely related to egg fanning rates. These relationships were independent of seasonal or population level environmental effects. These data suggest a strong three-way relationship among androgen levels, reproductive behavior, and stimuli associated with the progressing brood cycle.

Androgens↗
PubMedDate not supplied

Sexual dimorphism in the vomeronasal pathway and sex differences in reproductive behaviors.

Several years ago we hypothesized that the vomeronasal system (VNS), a complex neural network involved in the control of reproductive behavior, might be sexually dimorphic. This hypothesis sprung from several facts; (a) the existence of steroid receptors in the VNS; (b) sexual dimorphism was already described in some structures that receive vomeronasal input, such as the medial preoptic area, the ventromedial hypothalamic nucleus, the ventral region of the premammillary nucleus and the medial amygdaloid nucleus; and (c) the vomeronasal organ, which is the receptor organ of the VNS, was also sexually dimorphic. After that point, the accessory olfactory bulb (AOB), the bed nucleus of the accessory olfactory tract (BAOT) and the bed nucleus of the stria terminalis were found to be sexually dimorphic. The aim of the present review is to show the experimental facts that confirm our earlier hypothesis and, consequently, to present the existence of a sexually dimorphic multisynaptic pathway for the first time in mammals. Sexual dimorphism in the VNS might provide a comprehensive approach to understanding the neural bases of sexually dimorphic reproductive behavior and it is suggested here that the greater number of neurons which male rats present in relation to females in most VNS structures might contribute to the inhibition of the expression of feminine copulatory behavior (lordosis) and maternal behavior in males. In addition, the mechanisms that control the development of sexual dimorphism in the VNS are discussed. The discussion takes into account the two patterns of sexual dimorphism found in the rat brain. Estrogens seem to promote the development of sexual dimorphism in both male and female rats. However, an inhibitory role of androgens might be necessary to hypothesize when males or females present a lower number of neurons and/or volume than the opposite sex. There are experimental data supporting this hypothesis in the female, since dihydrotestosterone seems to facilitate neuronal death in VNS structures, such as the AOB and the BAOT, in which females present a lower number of neurons and volume than male rats. Finally, since the lateral division of the bed nucleus of the stria terminalis, which belongs to the main olfactory system (MOS), is sexually dimorphic and presents anatomical relationships with some VNS structures the MOS might be sexually dimorphic.

Animals↗
PubMed2004

The appearance of a protein kinase A-regulated splice isoform of slo is associated with the maturation of neurons that control reproductive behavior.

In response to brief synaptic stimulation that activates protein kinase A (PKA), the bag cell neurons of Aplysia trigger the onset of reproductive behaviors by generating a prolonged afterdischarge. In juvenile animals, such afterdischarges are inhibited by a high density of Ca2+ -activated K+ (BK) channels, encoded by the slo gene. An increase in this current also follows an afterdischarge in mature animals, contributing to a subsequent refractory state that limits reproductive behaviors. Using a bag cell cDNA library, we have isolated two alternative transcripts of the slo gene, differing in the presence (slo-a) or absence (slo-b) of a consensus phosphorylation site for PKA. Expression of either isoform in Chinese hamster ovary cells produced Ca2+ - and voltage-dependent channels with macroscopic and unitary properties matching those in bag cell neurons. The isoforms differed, however, in their response to application of the catalytic subunit of PKA, which reduced the open probability of Slo-a, an effect that was reversed by a PKA inhibitor. In contrast, PKA had no effect on Slo-b. By immunocytochemistry, we determined that the PKA-regulated Slo-a subunit is present in adult, but not juvenile, bag cell neurons. Patch clamp recordings from adult and juvenile bag cell neurons confirmed that PKA decreases BK channel activity only in adults. Our findings suggest that a change in the identity of Slo isoforms expressed during development allows mature neurons to generate afterdischarges that are required for reproduction.

Alternative Splicing↗
PubMed1992

Effects of prenatal testosterone and ATD on reproductive behavior in guinea pigs.

Most sexual dimorphisms in reproductive behavior are hormonally organized in the guinea pig. The study sought to determine whether the sexually dimorphic requirement for the aromatization of testosterone in the activation of mounting is organized by testosterone prenatally and whether aromatization of testosterone contributes to the organization of mounting behavior. Pregnant females were treated with testosterone, the aromatase inhibitor ATD, or vehicle from days 28-65 of gestation. The offspring were gonadectomized and tested as adults for lordosis and androgen-activated mounting behavior. Prenatal testosterone treatments altered the hormonal requirements for androgen-activated mounting in females such that they resembled normal males, and did not require aromatization as adults. Prenatal inhibition of aromatase activity decreased mounting activity in females but not in males. This treatment had no influence on lordosis in either sex. The results support the hypothesis that the same hormones that activate mounting behavior in the adult guinea pig are responsible for the organization of mounting behavior.

Androstatrienes↗
PubMed2004

Gonadal hormones masculinize and defeminize reproductive behaviors during puberty in the male Syrian hamster.

Three experiments were conducted to test whether testicular hormones secreted during puberty masculinize and defeminize the expression of adult reproductive behavior. Experiment 1 tested the hypothesis that gonadal hormones during puberty masculinize behavioral responses to testosterone (T) in adulthood. Male hamsters were castrated either before puberty (noTduringP) or after puberty (TduringP). All males were implanted with a 2.5-mg T pellet 6 weeks following castration and tested once for masculine reproductive behavior 7 days after the onset of T replacement. TduringP males displayed significantly more mounts, intromissions, and ejaculations than noTduringP males. Experiment 2 tested the hypothesis that gonadal hormones during puberty defeminize behavioral responses to estrogen (EB) and progesterone (P). Eight weeks following castration, noTduringP and TduringP males were primed with EB and P and tested for lordosis behavior with a stud male. Behavioral responses of males were compared to that of ovariectomized (OVX) and hormone primed females. NoTduringP males and OVX females displayed significantly shorter lordosis latencies than TduringP males. Experiment 3 investigated whether prolonged T treatment or sexual experience could reverse the deficits in masculine behavior caused by the absence of T during puberty. Extending the T treatment from 7 to 17 days did not ameliorate the deficits in masculine behavior caused by absence of T during puberty. Similarly, when the level of sexual experience was increased from one to three tests, the deficits in masculine behavior persisted. These studies demonstrate that gonadal hormones during puberty further masculinize and defeminize neural circuits and behavioral responsiveness to steroid hormones in adulthood.

Animals↗
PubMed1987

Effects of the antiandrogens cyproterone acetate and flutamide on male reproductive behavior in a lizard (Anolis sagrei).

This study examined the effects of the antiandrogens cyproterone acetate (CA) and flutamide (F) on male reproductive behavior in the lizard Anolis sagrei. Reproductively active males were implanted with subcutaneous pellets of either CA, F, or placebo (P). Pellets delivered CA and F at a constant rate of 0.1 mg/day. Three weeks after implantation, males were tested with stimulus males and two days later with stimulus females. Cyproterone acetate inhibited aspects of male aggressive and sexual behavior, and reduced testis weight and size of the renal sex segment. Plasma testosterone (T) levels in CA-treated males were not significantly different than those of P-treated males. Flutamide did not inhibit aggressive or sexual behavior, but did decrease testis weight as well as the size of the renal sex segment. Plasma T levels were significantly higher in F-treated males than in P-treated males. These data suggest that CA, an antiandrogen with antigonadotropic activity, may be used to inhibit reproductive behavior in male lizards.

Aggression↗
PubMed1986

Effect of flutamide (an antiandrogen) and diethylstilbestrol on the reproductive behavior of Japanese quail.

Three experiments were conducted in order to investigate the role of brain androgen and estrogen receptors in sex hormone activated male reproductive behavior in Japanese quail. In Experiment 1, castrated male quail were injected with oil, testosterone propionate (TP), flutamide (FLUT), an androgen antagonist, or TP+FLUT. Males given TP+FLUT, compared with birds receiving TP alone, strutted much less and had smaller proctodeal (foam) glands. Copulation was reduced by FLUT only on the last test day and only on one measure (number of head grabs + mounts). These results suggest that binding of testosterone or one of its metabolites to an androgen receptor is part of the mechanism of TP activated strutting, and therefore that central nervous system androgen receptors are involved in a male reproductive behavior pattern. In Experiment 2, castrated male quail were injected with oil, with 50 micrograms estradiol benzoate (EB), or with 25, 50 or 100 micrograms diethylstilbestrol (DES), a synthetic estrogen that does not bind to androgen receptors. EB but not DES activated copulation to a significant extent. In Experiment 3 male and female quail with photically regressed gonads were given intraperitoneal Silastic implants of DES, estradiol (E) or cholesterol. DES was highly effective at activating male-typical copulation in males and receptivity in both sexes. Thus hormonal interaction with estrogen receptors alone is sufficient for the activation of male-typical as well as female-typical copulatory behavior in this species.

Anilides↗
PubMed1999

Influence of family tradition on reproductive behavior of Gypsy population.

INTRODUCTION: Stability of traditional opinion in different ethnic communities determines to a great degree the demographic behavior of their members. AIM: To analyze the influence of family traditions and system of values on the reproduction of gypsy population. MATERIALS AND METHODS: The opinions of 495 Gypsy women in reproductive age was studied by direct individual questionnaire. The answers characterizing the reproductive behavior of two successive generations were analyzed. The following statistical analyzes were applied: descriptive statistics, chi-square and t-tests. All p-values are two-tailed. The statistical analyses were made on a PC using SPSS 5.0.2. RESULTS: Mean age at marriage in different generations under study was similar (it is 15.50 +/- 0.10 years in the present generation vs. 15.58 +/- 0.09 years in the previous generation, p > 0.05). The same is valid for the mean age at the first birth (16.98 +/- 0.11 years vs. 17.04 +/- 0.10 years, respectively, p > 0.05). However, there was a statistically significant difference in the mean number of live-births between the generations (2.37 +/- 0.05 vs. 4.10 +/- 0.09, respectively, p < 0.001). The latter finding might be explained by fact that the women from the present generation are still in their reproductive period. CONCLUSION: It is obvious that family traditions may have, to a certain extent, an influence on the patterns of reproductive behavior in gypsy population. These traditions represent an indispensable part of their lifestyle and their intentions to have many children.

Adult↗
PubMed2003

Pituitary adenylate cyclase-activating peptide: a pivotal modulator of steroid-induced reproductive behavior in female rodents.

Pituitary adenylate cyclase-activating polypeptide (PACAP) regulates the secretion of GnRH into the hypothalamic hypophysial portal system and sensitizes the pituitary for release of hormones that trigger ovulation. Because reproductive behavior is synchronized with GnRH release, the present study was undertaken to determine whether PACAP in the ventromedial nucleus (VMN) plays a role in receptivity. To this end, we used rat and mouse reproductive behavioral models to determine the biological relationship between PACAP and steroid receptor function in females. We provide evidence for the requirement of PACAP in the VMN for progesterone (P)-dependent sexual behavior in estrogen (E)-primed females. We clarify the biological and molecular mechanisms of PACAP activity by showing 1) that inhibition of endogenous PACAP suppresses P receptor (PR)-dependent sexual behavior facilitated by the steroid P or D1-like agonist SKF38393 and 2) that PR, steroid receptor coactivators-1 and -2, and new protein synthesis are essential for ligand independent PACAP-facilitated behavior. These findings are consistent with convergence of PACAP-mediated cellular signals on PR for genomic activation and subsequent behavioral changes. Further, we show that steroids regulate both endogenous PACAP mRNA in the VMN and immunoreactive PACAP in the medial basal hypothalamus and cerebral spinal fluid for ligand-dependent, steroid receptor-dependent receptivity. The present findings delineate a novel, steroid-dependent mechanism within the female hypothalamus by which the neuropeptide PACAP acts as a feed-forward, paracrine, and/or autocrine factor for synchronization of behavior coordinate with hypothalamic control of ovulation.

Animals↗
PubMed1991

Thyrotropin-releasing hormone facilitates display of reproductive behavior and locomotor behavior in an amphibian.

In the amphibian brain, thyrotropin-releasing hormone (TRH) is present in many regions outside the hypothalamus. The functions of this extrahypothalamic TRH however are unknown. We sought to determine whether TRH or its metabolites altered reproductive behaviors (amplectic clasping behavior) or locomotor behaviors of the male South African clawed frog, Xenopus laevis. TRH-injected (100 micrograms; dorsal lymph sac injection) male Xenopus displayed significantly fewer amplectic clasp attempts and longer clasp durations than saline-injected controls. The TRH metabolites, TRH acid and histidylproline diketopiperazine, similarly altered clasping behavior. Several hormones released by TRH, including thyroid-stimulating hormone, melanocyte-stimulating hormone, prolactin, and dopamine, had no significant effect on clasp frequency or duration. Locomotor activity in Xenopus males was increased significantly after 15 min following TRH injection (150 micrograms); this effect persisted for at least 1 hr. The metabolites did not alter locomotion. These studies indicate that TRH can facilitate the display of two behaviors in the South African clawed frog. Effects of TRH on locomotor and reproductive behaviors thus appear in several vertebrate classes. These behavioral actions of TRH likely occur through different mechanisms or at different sites.

Animals↗
PubMed1991

Reproductive behavior of thalassemic couples segregating for Cooley anemia.

The reproductive behavior in 1984 of families segregating for Cooley anemia in Ferrara was compared with that of a control group of families, matched for some biological variables which affect fertility. At the resolution power of the sample, it was found that there is no significant difference in these variables due to segregation for Cooley anemia, and it appears that there is no longer significant reproductive compensation in thalassemic couples, although a tendency to compensate does still exist. The increased life span of children affected by Cooley anemia, due to improvements in treatment in the past decade, is probably the main reason why the compensatory reproductive behaviour of the past has almost disappeared.

Adult↗
PubMed1986

Hormonal regulation of male reproductive behavior in the lizard Anolis sagrei: a test of the aromatization hypothesis.

This study examined the hypothesis that aromatization of testosterone (T) to estradiol (E) is required to activate reproductive behavior in castrated male lizards (Anolis sagrei). Adult, reproductively active males were assigned to an intact control group or to one of four treatment groups. Treatment males were castrated and 1 week later three of the four castrated groups were implanted with subcutaneous pellets containing either 0.05 mg of E, 0.5 mg of T, or 0.5 mg of dihydrotestosterone (DHT). Two weeks after pellet implantation, males were tested with stimulus males, and 2 days later were tested with stimulus females. Behavioral tests were of 15-min duration and were videotaped. Significantly fewer E-treated castrates erected a crest in tests with stimulus males than did intact males. In tests with stimulus females, significantly fewer E-treated castrates displayed, neck-gripped, and intromitted than did intact males. Estradiol-treated castrates also showed significantly less display behavior than did intact males. However, aggressive and sexual behavior of DHT-treated castrates was not significantly different from that of intact males. The same was true for T-treated castrates with the exception that display behavior in tests with stimulus females was reduced compared to that of intact males. The results suggest that aromatization of T to E is not required for induction of androgen-dependent reproductive behavior in this lizard.

Aggression↗
PubMed1984

Women's program impact on village women's contraceptive and reproductive behavior in rural Bangladesh.

The author examines the impact on contraceptive and reproductive behavior of a social program designed to teach trade skills and family planning to women in rural Bangladesh. The focus is on "whether a social program that is designed to use a particular group as catalysts brings about any change in [the] contraceptive and reproductive behaviour of the community that is indirectly exposed to the program." A sample of 625 women indirectly exposed to the program and 312 women from non-program, control villages were interviewed; baseline data are from the 1976 Bangladesh Fertility Survey. It is found that "the indirectly exposed and unexposed women are very similar in their contraceptive and reproductive behaviour. The impact of the directly exposed women (trained women) in family planning was trivial even after three years of program operation. Socio-economic and demographic characteristics of both the groups are also similar....The current use among the indirectly exposed women was only 12% as compared to 10% for the unexposed women."

Asia↗
PubMed1994

Effects of intrahypothalamic administration of antisense DNA for progesterone receptor mRNA on reproductive behavior and progesterone receptor immunoreactivity in female rat.

Since reproductive behaviors of female rats can be correlated with estrogen-induced increases in progestin binding by hypothalamic neurons, we hypothesized that specific progesterone receptor (PR) antisense DNA sequences might decrease these behaviors. Antisense oligonucleotides (15 bases), spanning the translation start site of rabbit PR mRNA, were microinjected directly among ventromedial hypothalamic neurons, and their behavioral effects were compared to control oligonucleotides composed of the same nucleotide bases in scrambled order. When applied 12 but not 24 hr after estradiol, the PR antisense treatment significantly reduced iordosis behavior, measured either as a reflex or in a mating behavior test. Notably, proceptive behaviors, which are strongly progesterone dependent, were greatly reduced in their occurrence (80% decrease). To see if PR protein was also reduced, antisense DNA was administered near the ventromedial hypothalamus on one side of the brain, while the other side received the scrambled control sequence or vehicle. The total number of PR-immunoreactive cells on the antisense side was significantly lower in the ventromedial nucleus, but not in control measurements from the medial preoptic area. Interrupting gene expression for PR, a transcription factor, in hypothalamic neurons, can have behavioral and immunocytochemical effects.

Animals↗
PubMedDate not supplied

The evolution of bourgeois, parasitic, and cooperative reproductive behaviors in fishes.

Among vertebrate classes, fishes exhibit by far the greatest variability in competitive and cooperative behaviors in male reproduction. Scramble competition between reproductive males is one possibility. Another possibility occurs when resources, mates, or locations can be monopolized, in which case males may invest in primary access to fertilizations by adopting a "bourgeois" strategy, or they may employ alternative mating tactics to evade the reproductive monopoly of other males. Adaptations in morphology, physiology, and behavior to bourgeois and alternative phenotypes are highly divergent. Here I review the functional characteristics that differ between bourgeois and parasitic phenotypes, and discuss the variability of alternative reproductive tactics at the levels of plasticity, determination, and selection. Examples will illustrate the importance of ecology, and will suggest that variation in reproductive tactics is largely adaptive. Behavioral solutions to competition for mates and fertilizations often involve agonistic behavior and conflict, but also cooperation among competitors (e.g., when subordinate males pay a price to bourgeois males for gaining access to fertilizable eggs). Application of molecular genetic tools has helped to uncover intricate sexual and social relationships in various fish species, including species that display some of the most complex reproductive and social patterns known among the vertebrates.

Agonistic Behavior↗