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PubMed1994

Early postnatal diazepam treatment of rats and neuroimmunocompetence in adulthood and senescence.

Functional teratogenic risk of perinatal diazepam (D) treatment was studied in animal model experiments using early postnatal D administration in rats (single dose of 10 mg/kg sc in 7-day-old pups) and long-term follow-up till the age of 18 months with monitoring of behavior, reproductive functions, brain biochemical variables, and immune system reactivity. Behavioral tests carried out at the age of 6, 12, and 18 months indicated higher emotionality and deviations of novelty reaction in D rats in comparison with controls, and these differences decreased with aging. However, no deficits were found in memory testing. D rats revealed some transitional alterations of monoamine neurotransmission in the hypothalamus (5-HT) and striatum (DA) and minor defects in reproductive functions (irregular estrous cycles in females). Significant depression of immune response in D rats persisting for the whole life may be considered as a serious risk of neonatal D treatment.

Aging↗
PubMed2006

Factors associated with the reproductive health risk behavior of high school students in the Republic of the Marshall Islands.

This study revealed factors associated with reproductive health risk behavior among high school students in the Republic of the Marshall Islands. The survey was conducted among high school students from grades 9 through 12 at 2 schools in Majuro, the capital of the Marshall Islands. The questions asked inquired about knowledge, attitude, and behavior related to reproductive health, experience of sexual acts and pregnancy. Multiple logistic regression analysis was performed to assess the association between risk behavior and knowledge, attitude, and other factors. Data obtained from 433 students were used in the analysis. Factors significantly associated with reproductive health risk behavior among both the boys and the girls were a negative attitude toward condom use (odds ratio of the risk group to the low-risk group: boys, 19.54; girls 4.10), not considering receiving public health information and services as a human right (8.10, 3.96), and not knowing where to go for consultation about questions and concerns related to sex (3.32, 4.73). A factor associated with risk behavior in boys alone was acceptance of sexual acts without love (8.46), and factors in girls alone were insufficient knowledge concerning routes of infection by sexually transmitted diseases (6.75) and lack of future life plans (5.00). Neither age nor sex education was a significant predictor. In conclusion, considering reproductive health not to be a personal right was associated with the risk behavior of high school students in the Marshall Islands in regard to reproductive health.

Access to Information↗
PubMed1991

Behavioral, hormonal, and morphological responses of free-living male pied flycatchers to estradiol treatment of their mates.

A field experiment was performed implanting female pied flycatchers (Ficedula hypoleuca) during the nest-building period with silastic tubes containing 17 beta-estradiol. Control females were given empty silastic tubes. The pied flycatcher is a polygamous and polyterritorial bird species. During two successive breeding seasons effects on reproductive behavior and the reproductive systems of males were studied. Reproductive success was not affected by the treatment. Estradiol treatment of females caused marked changes in the behavior of males, increasing aggressive and mate-guarding behavior. The results of the present study also support the idea that cuckoldry is a problem for the territory holder. Fewer males paired with estradiol-treated females established secondary territories, and significantly more of the polyterritorial males from the experimental population showed up in the home-territory when a simulated territorial intrusion was performed there. Control males were much more successful in getting a second female to breed. Spermatogenesis and hormonal cycles (DHT, LH, and testosterone) in males were not prolonged as a result of estradiol treatment of the females.

Agonistic Behavior↗
PubMed2004

The neural basis of puberty and adolescence.

The pubertal transition to adulthood involves both gonadal and behavioral maturation. A developmental clock, along with permissive signals that provide information on somatic growth, energy balance and season, time the awakening of gonadotropin releasing hormone (GnRH) neurons at the onset of puberty. High-frequency GnRH release results from disinhibition and activation of GnRH neurons at puberty onset, leading to gametogenesis and an increase in gonadal steroid hormone secretion. Steroid hormones, in turn, both remodel and activate neural circuits during adolescent brain development, leading to the development of sexual salience of sensory stimuli, sexual motivation, and expression of copulatory behaviors in specific social contexts. These influences of hormones on reproductive behavior depend in part on changes in the adolescent brain that occur independently of gonadal maturation. Reproductive maturity is therefore the product of developmentally timed, brain-driven and recurrent interactions between steroid hormones and the adolescent nervous system.

Adolescent↗
PubMed1995

Oxytocin and rodent sociosexual responses: from behavior to gene expression.

In most mammals, gonadal steroid hormones are required for the expression of species-typical reproductive behavior. Over the past few years it has become evident that neuropeptides, such as oxytocin (OT) and vasopressin (AVP), also play a key role in the regulation of both social and sexual behavior. Through studies of gonadal steroid/neuropeptide interactions, we have been able to discover species differences in behavioral and physiological responses to OT that may be associated with species-specific distributions of OT receptors or differential levels of OT gene expression in the central nervous system (CNS). However, the characterization of OT's behavioral effects has been conducted primarily in rats and the neural mechanisms underlying these behaviors are not clearly understood. The present paper will describe and discuss the biological significance of OT-mediated behavioral responses in both female and male prairie voles and rats, speculate on the neural mechanisms (OT receptor regulation) and reproductive physiology involved in species-specific sociosexual behavior, and present new methodologies for studying signal transduction mechanisms involved in OT gene expression in the CNS.

Animals↗
PubMed1998

Adaptations to subordinate status in female marmoset monkeys.

In singular cooperatively breeding mammals, social status is a key determinant of female reproductive success. Usually only one dominant female breeds in a social group. In the common marmoset (Callithrix jacchus), a cooperatively breeding primate, adaptations to nonbreeding subordinate status appear to parallel those found in social insect societies which demonstrate similar skew to the marmoset in female reproductive success. Female marmosets exhibit rank-related polyethism in behavior, reproductive neuroendocrinology and non-reproductive physiology, and subordinates participate in alloparental care and territory defense. Olfactory, visual and behavioral cues from dominant female marmosets provide important proximate cues regulating ovarian inhibition in female subordinates. Cooperatively breeding marmosets, therefore, appear to have developed specific neural and neuroendocrine adaptations to subordinate social status analogous to those found in social insects such as the lower wasps, bees and termites. Such parallel developments probably reflect the outcome of repeated convergent evolutionary attempts at adapting to environmental conditions not readily conducive to dispersal and independent breeding.

Adaptation, Psychological↗
PubMed2005

Reproductive success of broiler breeders in natural mating systems: the effect of male-male competition, sperm quality, and morphological characteristics.

In natural mating systems in which broiler breeder males compete for females, reproductive behavior plays an important role in male fertility, along with sperm competition and morphological and physiological characteristics. We investigated the effect of male-male competition compared with a noncompetitive situation on fertility, sperm quality, and morphological traits. Six groups of 3 males and 12 females were housed in mixed-sex pens. Their frequency of mating was recorded, and progeny of each male was determined through DNA fingerprinting. Males with the highest and the lowest mating frequencies were later placed into groups of 1 male and 4 females, their behavior was recorded, and their fertility was calculated. We collected data on semen quality (semen volume, sperm concentration, and mobility) and morphometrical characters. Finally, females were artificially inseminated with sperm from highest frequency, lowest frequency, or a mix, paternity and fertility were estimated. Our results indicate that heavier males had higher frequency of matings without cloacal contact, and males with smaller combs had more mating attempts. We also detected that males with high sperm concentration had lower fertility. However, we found an overall lack of association between mating behavior, morphometrical traits, sperm quality, and fertility. This, together with the discrepancy of results in fertility when compared with artificial insemination conditions, suggest a multifactorial nature of the fertility of broiler breeder males in natural mating systems. In addition we observed a high male fertility when housed individually, suggesting that male fertility is a relative parameter that depends upon the reproductive quality of the other male competitors within the group.

Animals↗
PubMed1994

Behavioral and neurobiological implications of sex-determining factors in Drosophila.

The function of the central nervous system as it controls sex-specific behaviors in Drosophila has been studied with renewed intensity, in the context of genetic factors that influence the development of sexually differentiated aspects of this insect. Three categories of genetic variations that cause anomalies in courtship and mating behaviors are discussed: (1) mutants isolated with regard to courtship defects, of which putatively courtship-specific variants such as the fruitless mutant are a subset; (2) general behavioral and neurological variants (including sensory and learning mutants), whose defects include subnormal reproductive performance; and (3) mutations of genes within the sex-determination regulatory hierarchy of Drosophila, the analysis of which has included studies of reproductive behavior. Recent studies of mutations in two of these categories have provided new insights into the control of neuronally based aspects of sex-specific behavior. The doublesex gene, the final factor acting in the sex-determination hierarchy, had been previously thought to regulate all aspects of sexual differentiation. Yet, it has been recently shown that doublesex does not control at least one neuronally-determined feature of sex-specific anatomy--a muscle in the male's abdomen, whose normal development is, however, dependent on the action of fruitless. These considerations prompted us to examine further (and in some cases re-examine) the influences exerted by sex-determination hierarchy genes on behavior. Our results--notably those obtained from assessments of doublesex mutations' effects on general reproductive actions and on a particular component of the courtship sequence (male "singing" behavior)--lead to the suggestion that there is a previously unrecognized branch within the sex-determination hierarchy, which controls the differentiation of the male- and female- specific phenotypes of Drosophila. This new branch separates from the doublesex-related one immediately before the action of that gene (just after transformer and transformer-2) and appears to control as least some aspects of neuronally determined sexual differentiation of males.

Animals↗
PubMed2000

Comparative thermoregulation of sympatric endothermic and ectothermic cicadas (Homoptera: Cicadidae: Tibicen winnemanna and Tibicen chloromerus).

Measurements of body temperature in the field demonstrated that endothermic cicadas regulate body temperature by behavioral mechanisms as well as by endogenous heat production. Regression analysis suggests both endothermic and ectothermic species are thermoregulating. Body temperature of endothermically active cicadas without access to exogenous heat is approximately the same as the body temperature of basking cicadas. Tibicen winnemanna (Davis) raises body temperature in the field with the heat produced in flight or through the activation of the flight musculature without the act of flight. T. chloromerus (Walker) uses solar radiation to elevate body temperature to the level necessary for activity. The thermal responses of each species are related to its activity patterns with minimum flight temperature and shade-seeking temperatures significantly lower in the endothermic T. winnemanna. Heat torpor temperature appears to be related to the environment rather than behavior pattern. Endothermy in cicadas may serve to uncouple reproductive behavior from environmental constraints; to circumvent possible thermoregulatory problems; to permit the utilization of habitats unavailable to strictly ectothermic cicadas; to reduce predation; to optimize broadcast coverage and sound transmission; and to decrease possible acoustic interference.

Adaptation, Physiological↗
PubMedDate not supplied

Reproductive motivation and family-size preferences among Nigerian men.

Data collected from 3,073 couples in four Nigerian cities and one semi-urban settlement were used to examine reproductive decision-making and male motivation for large family size. The report concludes that the characteristic male-dominant and patrilineal traditions support large family size and that men's reproductive motivation, to a large extent, affects the reproductive behavior of their wives. Therefore, the factors influencing men's reproductive outcomes and intentions are considered important for fertility transition in Nigeria. Male education, age at marriage, monogamy, interspousal communication, and intention not to rely on children for old-age support are significantly related to smaller actual family size and preferences for smaller families, while being in a male-dominant family setting has a strong relation with large family size and preferences for larger families. The policy implication of this study is the need for programs targeted at men and designed to change their attitudes about population matters and motivate them, and hence their wives, to produce smaller families.

Adult↗
PubMed1992

Photoperiod modulates pubertal shifts in behavioral responsiveness to testosterone.

This study examined the effect of photoperiod on pubertal maturation of steroid-dependent reproductive behaviors in male European ferrets (Mustela putorius furo). In the first experiment, levels of neck gripping, mounting, and pelvic thrusting in gonadally intact prepubertal (PRE) ferrets were compared with those of adults that had undergone puberty either while housed in short days (8 hr light/16 hr darkness per day; SD), or after transfer from SD to long days (18 hr light/6 hr darkness per day; LD) at 12 weeks of age. Both LD and SD adults demonstrated significantly greater amounts of neck gripping and mounting than PRE males. In addition, a significantly greater proportion of adults in both SD and LD displayed at least one incidence of the three behaviors compared to PRE ferrets. There were no statistically significant differences in behavior of the gonadally intact LD and SD adults. In the second experiment, dose-response curves for behavioral responses to subcutaneous injections of 0, 0.5, 1.25, 2.5, 5, and 10 mg/kg testosterone propionate (TP) in oil were generated in castrated PRE, SD, and LD males. The lowest dose of TP elicited significantly greater amounts of all three behaviors in LD adults than in PRE ferrets. In addition, levels of mounting and thrusting elicited by the lowest dose of TP were significantly greater in LD adults than in SD adults. These data indicate that pubertal activation of male sexual behavior in male ferrets is accompanied by a pubertal increase in responsiveness to the behavioral effects of testosterone. Furthermore, the degree of behavioral responsiveness of adult ferrets to testosterone is modulated by environmental photoperiod experienced during reproductive maturation.

Animals↗
PubMed2004

Hormonal symphony: steroid orchestration of gene modules for sociosexual behaviors.

Genes induced by estrogens in the mammalian forebrain influence a variety of neural functions. Among them, reproductive behavior mechanisms are very well understood. Their functional genomics provide a theoretical paradigm for linking genes to neural circuits to behavior. We propose that estrogen-induced genes are organized in modules: Growth of hypothalamic neurons; Amplification of the estrogen effect by progesterone; Preparative behaviors; Permissive actions on sex behavior circuitry; and Synchronization of mating behavior with ovulation. These modules may represent mechanistic routes for CNS management of successful reproduction. Moreover, new microarray results add estrogen-dependent genes, including some expressed in glia, suggesting possible hormone-dependent neuronal/glial coordination.

Animals↗
PubMed1993

Reproductive failure of dominant males in the poeciliid fish Limia perugiae determined by DNA fingerprinting.

Hierarchical structures among male individuals in a population are frequently reflected in differences in aggressive and reproductive behavior and access to the females. In general, social dominance requires large investments, which in turn then may have to be compensated for by high reproductive success. However, this hypothesis has so far only been sufficiently tested in small mating groups (one or two males with one or two females) due to the difficulties of determining paternity by conventional methods. DNA fingerprinting overcomes these problems by offering the possibility to determine genetic relationships and mating patterns within larger groups [Burke, T. (1989) Trends Ecol. Evol. 4, 139-144]. We show here that in the poeciliid fish Limia perugiae, in small mating groups the dominant male has a mating success of 100%, whereas in larger groups its contribution to the offspring unexpectedly drops to zero.

Animals↗
PubMed1992

The intrauterine position phenomenon and precopulatory behaviors of house mice.

The effects of intrauterine position on two sexually dimorphic, precopulatory, reproductive behaviors, were investigated in male and female mice of three different genetic strains. The two behaviors were: (i) urinary odor preference and (ii) ultrasonic mating vocalizations. In addition, anogenital distance was measured both at birth and later in adulthood as a morphological index of masculinization. The intrauterine positions of individual mice relative to male and female siblings were classified according to two different classification schemes based upon hypotheses of interfetal steroid transfer: (i) the contiguity hypothesis which is based on diffusion of steroids within the uterus and (ii) the transvasculature hypothesis which posits the movement of fetal steroids via the maternal vasculature. In contrast to expectations, intrauterine position defined by either the contiguity hypothesis or the transvasculature hypothesis, did not have a consistent effect on urinary odor preferences, ultrasonic mating vocalizations, or anogenital distance in male and female house mice.

Animals↗
PubMed1999

Functional dichotomy within the vomeronasal system: distinct zones of neuronal activity in the accessory olfactory bulb correlate with sex-specific behaviors.

Chemosensory neurons in the vomeronasal organ (VNO) detect pheromones that elicit social and reproductive behaviors in most terrestrial vertebrates. Vomeronasal receptor neurons are chemoarchitecturally divided into two populations based on their position in the VNO, the type of G-protein subunit expressed, the family of putative pheromone receptor expressed, and termination site of their axons in the accessory olfactory bulb (AOB). To investigate the functional implications of these two segregated VNO-AOB pathways, we stimulated mice with pheromonal cues associated with different behavioral contexts and examined cellular activation patterns in the AOB. Exposure of ICR male mice to BALB/c males resulted in aggressive behavior, accompanied by a VNO-dependent increase in c-fos immunoreactivity in a cluster of cells located almost exclusively in the caudal AOB in both strains. This caudal cluster of activated cells did not appear to require the overt display of aggressive behavior because it was present in both the dominant and submissive males and could be evoked when the stimulus animal was anesthetized. In contrast, exposure of an ICR male to an ICR female in diestrus resulted in activation of cells located predominantly in the rostral AOB. Our findings indicate that male-to-male interactions involving interstrain recognition activate a separate population of vomeronasal receptor neurons than chemosensory cues detected in a sexual context. The results suggest that the dichotomy in the peripheral vomeronasal system serves to separate pheromones based on the behaviors they drive. As such, the results provide a bioassay for identifying pheromone molecules.

Aggression↗
PubMed1994

Behavioral and hormonal responses of male song sparrows to estradiol-treated females during the non-breeding season.

Previous studies on several species have shown that behavior of female vertebrates given estradiol implants to maintain sexual receptivity resulted in elevated levels of testosterone in males and even delayed termination of breeding in their otherwise untreated mates. However, the efficacy of such treatment in the non-breeding season was unclear. In this study, female song sparrows, Melospiza melodia morphna, given implants of estradiol in autumn showed elevated sexual behavior--especially "chitters," a loud, female-specific vocalization used mostly during the breeding season. Males in autumn appeared to ignore the sexual behavior of these females, showed no difference in response to simulated territorial intrusion, and had basal circulating levels of testosterone when compared with males tested in an area of control females. However, by late winter (February) males in the area where females were treated with estradiol had elevated levels of testosterone compared to control males and those of both groups sampled in autumn. These data indicate that sexual behavior of females, experimentally induced by estradiol implants, failed to increase sexual and territorial behavior in males during the autumn. On the other hand, reproductive behavior of females did appear to accelerate the vernal increase in testosterone concentrations in blood of males.

Aggression↗
PubMed2006

Predicted seminal astacin-like protease is required for processing of reproductive proteins in Drosophila melanogaster.

During mating, males provide females with seminal fluids that include proteins affecting female physiology and, in some cases, reproductive behavior. In several species these male-derived modulators of reproduction are processed upon transfer to the female, suggesting molecular interaction between the sexes. Males could increase their reproductive success by contributing to regulation of this processing; consistent with this hypothesis, seminal fluids are rich in proteolysis regulators. However, whether these molecules carry out processing of male-derived reproductive modulators is unknown. We tested for this role using RNAi to knock down individually 11 Drosophila seminal fluid proteases and protease inhibitors. We found that CG11864, a predicted astacin-type metalloprotease in seminal fluid, is necessary to process two other seminal proteins: the ovulation hormone ovulin (Acp26Aa) and the sperm storage protein Acp36DE. This processing occurs only after all three proteins have entered the female. Moreover, CG11864 itself is processed inside males while en route to the female and before its action in processing ovulin and Acp36DE. Thus, processing of seminal proteins is stepwise in Drosophila, beginning in the male after the proteins leave their site of synthesis and continuing within another organism, the mated female, and the male-donated protease CG11864 is an agent of this latter processing.

Amino Acid Sequence↗
PubMed1997

Changing through doing: behavioral influences on the brain.

It seems self-evident that the brain controls behavior but does behavior also "control" the brain? This chapter examines evidence that behavior can and does influence specific aspects of brain structure and function. Evidence for such influence is easily obtained on an evolutionary time scale, since the selective forces found in the ecological niche of the animal are typically reflected in its sensory and motor activities as well as its body shape and behavioral habits. Similarly, during development, there is ample evidence that the behavior acts in concert with the environment to establish structural changes in the brain that last a lifetime. Perhaps most surprisingly there is now evidence that social behavior can cause changes in the brain in adult animals and that these changes are reversible. The changes caused by behavioral interactions can be dramatic and typically are related to reproductive behavior. Understanding the mechanisms responsible for dynamic changes in the nervous systems of adult animals is a major challenge and the discovery that it can occur may lead to insights about other systems where behavior sculpts the brain.

Animals↗