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PubMed2001

Measures of menopausal status in relation to demographic, reproductive, and behavioral characteristics in a population-based study of women aged 35-49 years.

The purpose of this cross-sectional analysis of women aged 35-49 years from the Third National Health and Nutrition Examination Survey, conducted between 1988 and 1994, was to assess associations with menopausal status based either on menstrual cycle patterns or on elevated (>20 IU/liter) follicle-stimulating hormone. Menstrual cycle-based menopausal status was defined for women who had not had surgical menopause by months since the last period (<2, 2-12, and >12 months for pre-, peri-, and postmenopause, respectively). Logistic regression was adjusted for age, smoking, and unilateral oophorectomy. Higher body mass index (> or =30 kg/m(2) compared with < 25.0 kg/m(2)) was associated with a lower likelihood of elevated follicle-stimulating hormone (odds ratio (OR)=0.6, 95% confidence interval (CI): 0.4, 0.9) but this association was not seen with the menstrual measure of menopause. Exercise (three or more times per week) was associated with a lower likelihood of being postmenopausal on the basis of menstrual (OR = 0.3, 95% CI: 0.2, 0.7) and hormonal (OR = 0.6, 95% CI: 0.4, 1.0) measures. Alcohol use also tended to be associated with postmenopausal status by either measure, but not significantly so. There was little evidence of associations with ethnicity, education, age at menarche, number of livebirths, and oral contraceptive use. Menstrual-based definitions of menopause can be misclassified for women with menstrual irregularity. This might explain why obese women were classified menstrually as menopausal while remaining hormonally premenopausal.

Adult↗
PubMed2004

The green anole (Anolis carolinensis): a reptilian model for laboratory studies of reproductive morphology and behavior.

The green anol (Anolis carolinensis) is an excellent reptilian model for studying reproductive behavior and the neural and muscular morphology that supports it. This lizard has been the subject of behavioral and ecological study for more than 100 yr, and a rich literature exists on its natural history. Both courtship and copulatory behaviors reveal sex and seasonal differences, which allow for the study of mechanisms regulation naturally occurring variation in performance at multiple levels within a single animal model. Green anoles are readily obtained due to their abundance in the wild; once in the laboratory, they are easily maintained, bred, and reared. Background on the natural history and husbandry of this lizard is provided, and the authors' research program on the regulation of reproductive anatomy and behavior is reviewed, Discussion includes the similarities and differences in the mechanisms mediating both structure and function compared with more traditional animal models. This type of comparative research will make it possible to identify the fundamental principles governing reproductive biology, thus advancing both basic and applied knowledge.

Animal Husbandry↗
PubMed1975

Birth trajectory under changing fertility conditions.

An initially stable population of women is assumed to shift its reproductive behavior to a different level either abruptly or in a prescribed gradual fashion. A closed-form solution which is exact up to about 30 years after the reproductive adjustment is found for the resulting birth trajectory. Exact expressions are also found for the long-time asymptotic behavior of both the birth trajectory and the total population size when the shift in reproductive behavior is to bare replacement level. Accurate approximations to these asymptotic results are then derived and used to illustrate why a growing population continues to grow even after shifting to bare replacement reproductive behavior.

Age Factors↗
PubMed1999

Genomic and membrane actions of progesterone: implications for reproductive physiology and behavior.

Progesterone, produced by the ovaries and adrenal glands, regulates reproductive behavior and the surge of luteinizing hormone which precedes ovulation by acting on neurons located in different parts of the hypothalamus. The study of the activation of these reproductive functions in female rats has allowed to explore the different mechanisms of progesterone action in the brain. It has allowed to demonstrate that new actions of the hormone, which have been observed in particular in vitro systems, are also operational in vivo, and may thus be biologically relevant. This mainly concerns the direct actions of progesterone on receptors of neurotransmitters such as oxytocin and GABA. Activation of the progesterone receptor in the absence of ligand by phosphorylation may also play a role.

Animals↗
PubMed1999

THE EVOLUTION OF ASEXUAL FUNGI: Reproduction, Speciation and Classification.

Phylogenetic and population genetic methods that compare nucleic acid variation are being used to identify species and populations of pathogenic fungi and determine how they reproduce in nature. These studies show that asexual or sexual reproductive morphology does not necessarily correlate with clonal or recombining reproductive behavior, and that fungi with all types of reproductive morphologies and behaviors can be accommodated by a phylogenetic species concept. Although approximately one fifth of described fungi have been thought to be asexual and clonal, recent studies have shown that they are also recombining. Whether a particular pathogen reproduces clonally or by recombination depends on factors relating to its biology and its distribution in space and time. Knowing the identity of species and populations and their reproductive modes, while taking a broad view of pathogen behavior in space and time, should enhance the ability of pathologists to control pathogens and even predict their behavior.

Journal Article↗
PubMed1986

Seasonality of adult male Japanese macaques (Macaca fuscata): androgens and behavior in a confined troop.

Seasonal variations in levels of serum testosterone, dihydrotestosterone (DHT), reproductive behavior, and social behavior were investigated in 12 adult males (5 to 20+ years of age) of the Oregon troop of Japanese macaques (Macaca fuscata). Blood samples were collected at 2- to 4-month intervals, and behaviors were monitored twice weekly over a 15-month period. Significant seasonal variations in levels of testosterone and DHT, and in frequencies of mount series, ejaculations, number of female partners, displays, courtship, and aggression were observed. Seasonal variations in reproductive and social behaviors did not correlate with seasonal variations in androgen levels because seasonal increases in these behaviors followed seasonal increases in the androgens with a 1- to 2-month delay. However, significant correlations between increased androgen levels and the onset of mating activity occur when mean monthly frequencies of mount series are shifted 1 to 2 months earlier to coincide with the rise in serum androgen levels. The frequency of adult male play and male-male mounting increased significantly when androgen levels were low. We suggest that photoperiod changes may function as a proximate cue in male Japanese macaques which induces a state of biological readiness for mating, and the behavioral consequences (i.e., mating) are then dependent upon the presence of receptive females.

Agonistic Behavior↗
PubMed1991

Common regulation of feeding and mating in Aplysia fasciata: pheromones released by mating and by egg cordons increase feeding behavior.

We examined whether pheromones released by reproductive behaviors (mating and egg-laying) affect feeding behavior. A preliminary experiment demonstrated that the quantity of food eaten can be used to measure the effects of pheromones on feeding. Using this measure, we then showed that Aplysia that were prevented from mating, but that were in the same aquarium as mating conspecifics, eat more food than do Aplysia in a medium lacking mating animals. Mating and feeding were not temporally correlated, indicating that pheromones released by mating probably do not initiate feeding, but rather modulate feeding after it has begun. Aplysia that were in the same aquarium as freshly deposited egg cordons also ate more than did animals in a medium lacking eggs.

Animals↗
PubMed1995

Social control of cell size: males and females are different.

Successful animals survive because they modify their behavior in response to changes in their physical and social environments. Some responses such as fleeing or fighting, are immediate and can be understood or at least described by their proximate causes. Other modifications occur in animals over a longer time frame because they require tissue growth (or loss), changes in responsiveness to signalling molecules, or other alterations in the regulation of physiological systems. There are numerous examples of the short-term cause-effect relationships which are known in some detail. In contrast, less is known about how long-term changes result from environmental or social signals. Since reproduction is arguably the single most important aspect of an animal's life, reproductive behaviors offer a unique chance to study such change. Reproduction requires exquisite coordination of physiological state and behavioral acts. Many aspects of reproductive behavior occur only under natural conditions so it is imperative to analyze naturally occurring behaviors in real animals, preferably in the natural habitat. We have been studying an African cichlid fish in natural and semi-natural conditions because the connection between physiology and behavior can be easily seen. Moreover, the consequence of social success can be traced directly to changes in the brain, both in the short and long term. In this species, territorial males inhibit sexual maturation of nonterritorial males during development. Even after a male becomes sexually mature and territorial, being defeated causes his gonads to regress rapidly.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Regulation of neuropeptide Y mRNA and peptide concentrations by copper in rat olfactory bulb.

Neuropeptide Y is highly abundant in both the peripheral and central nervous systems and is known to have diverse functions including regulation of feeding behavior, blood pressure, circadian rhythms, reproductive behavior and the response to stress. Northern analysis showed that copper deficiency increased brain NPY mRNA abundance particularly in the olfactory bulb (OB). These increases were not accompanied by alterations in food intake or blood pressure. After 4 weeks of a copper-restricted diet, OB copper concentrations decreased to 44% of control and NPY mRNA increased 1.5-fold. Addition of a copper chelator to the restricted diet, resulted in a two-fold increase in OB NPY mRNA over copper adequate controls. These results were confirmed in primary cultures of OB neurons suggesting that the regulation of NPY mRNA is at the level of the bulb rather than by a hormonal or other copper-regulated factor external to the OB. Immunoreactive NPY (IR-NPY) levels were not, however, increased following the 4 weeks of copper deficiency. Addition of the chelator resulted in a 1.4-fold increase in IR-NPY that, while statistically significant, was not proportional to the two-fold increase in NPY mRNA in the same study. This may suggest that copper deficiency inhibits the translational mechanisms responsible for the synthesis of NPY or that NPY is exported from the bulb in copper deficiency.

Animals↗
PubMed1981

Neural gonadal steroid actions.

Neurons sensitive to gonadal steroids are located strategically within neural circuits that mediate behaviors broadly related to the reproductive process. Some neuronal events and properties are regulated by these hormones. Variability in the occurrence and distribution of particular neural hormonal sensitivities across species may be related to variations in the hormonal requirements for sexual differentiation and for activation of reproductive behaviors.

Androgens↗
PubMed2002

Androgen effects on tyrosine hydroxylase cells in the northern leopard frog, Rana pipiens.

The interaction between gonadal steroids and dopamine neurons has been examined extensively in rodent model systems. However, there have been few investigations examining the functional relation between gonadal steroids and dopaminergic systems in nonmammalian taxa, and none in amphibians. We examined the effects of testosterone (T) and dihydrotestosterone (DHT) on changes in tyrosine hydroxylase immunoreactive (TH-ir) neuron number in the fore- and midbrain of male Rana pipiens, the Northern leopard frog, using a whole-mount immunohistochemical procedure. Gonadectomized males had significantly fewer TH-ir neurons in the medial preoptic area (POA), suprachiasmatic nucleus (SCN), and the caudal hypothalamus/posterior tubercular region (HY/TP) compared with T-implanted males. A follow-up study demonstrated that T- and DHT-implanted males had similar numbers of TH-ir neurons in these three regions compared with intact males and that all three of these groups possessed significantly more TH-ir neurons compared with gonadectomized males. These results suggest that circulating sex steroids have a significant impact on the activity of dopaminergic neurons in male R. pipiens. Although the function of these specific dopaminergic neurons is not yet known, the POA, SCN, and TP/DH are known to be integral brain regions underlying the neural control of reproductive behavior in frogs. These results suggest that dopamine may be important in controlling the behavior or neuroendocrine mechanisms of reproduction in these animals and that dopaminergic activity in these areas is regulated by gonadal steroids.

Animals↗
PubMed2000

The redemption of thalidomide: standardizing the risk of birth defects.

In this paper we examine how a standardized drug distribution system contributed to a therapeutic and symbolic make-over of thalidomide. In the 1960s, thalidomide was seen as a horror drug that caused severe birth defects among over 10,000 babies who were exposed to it in utero. Currently, thalidomide is viewed as a potentially life-saving drug which is being distributed in the USA. We discuss this transformation from a social worlds perspective, showing how the standardized drug distribution system normalized the risk of foetal birth defects, while preserving the autonomy of health care professionals. The distribution system accomplished this transformation by focusing on the risk associated with female reproductive behavior, and by providing close reproductive surveillance of female patients. This standardized system solidified social inequalities and professional power relationships, revealing assumptions about trust, responsibility and risk.

Abnormalities, Drug-Induced↗
PubMed1983

Reproductive functioning in the prenatally stressed female rat.

The reproductive behavior and physiology of female offspring of rats stressed during pregnancy were assessed. Mothers were restrained and placed under bright, hot lights from Day 14 through 21 of gestation. This treatment, which is known to disrupt the sexual behavior of male offspring, did not alter reproductive functioning in the female offspring. The females showed evidence of normal cyclicity, sexual behavior, pregnancy, parturition, pup survival, and maternal behavior when tested beginning at 70 or at 140 days of age.

Animals↗
PubMed1990

Aromatization mediates aggressive behavior in quail.

Although testosterone (T) stimulates aggressive and reproductive behaviors in males of many vertebrate species, it is now known that the full expression of T action in the brain requires aromatization to estradiol (E2) and subsequent interaction of locally formed E2 with nuclear estrogen receptors. In experiments reported here, we used a behavioral test which quantifies the response of an individual male Japanese quail (Coturnix coturnix japonica) to the visual stimulus of a conspecific. We have called this behavior aggression because it shares many features in common with traditional measures of aggression, e.g., predicting dominance and subordinance. Nevertheless, the behavior probably also combines a complex steroid-sensitive masculine behavior. The advantage of this test is that it allows the discrimination of individual differences in masculine behavior but avoids fighting and sexual encounters per se, thereby reducing effects of learning, a problem with previous tests of avian aggression. In addition, this test has been applied usefully to identify neuroendocrine correlates to male behavior. Using this test, the arousal of reproductively inactive males (hereafter referred to as aggression) is activated by administration of T or estradiol benzoate (EB), but not by 5 alpha-dihydrotestosterone (DHT). T-induced aggression was blocked by the aromatase inhibitor 4-hydroxyandrostenedione (OHA), an effect partially reversed by treatment with EB. In addition, OHA or the estrogen receptor blocker CI-628 reduced aggressiveness of reproductively active males whereas the androgen receptor blocker flutamide had no effect. Results with the 5 alpha-reductase inhibitor N,N-diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 alpha-carboxyamide (4-MA) were equivocal. Additionally, treatment of reproductively inactive quail with T or E2 but not DHT increased aromatase activity in the hypothalamus-preoptic area (HPOA). We conclude, therefore, that T to E2 conversion is essential for the activation of aggressiveness in this species. Although locally formed estrogen exerts its effects on aggression in part by increasing activity of aromatase per se, analysis of the time course of behavioral induction or suppression by the various treatments suggests that the response has multiple components, including both short latency, receptor-independent and long latency, receptor-dependent events.

5-alpha Reductase Inhibitors↗
PubMed1991

Chlordecone (Kepone) on the night of proestrus inhibits female sexual behavior in CDF-344 rats.

The effect of the estrogen-like chlorinated pesticide chlordecone (Kepone) on sexual behavior was examined in proestrous rats following treatment with 25, 50, or 75 mg/kg chlordecone. In most animals, sexual behavior, both receptivity and proceptivity, was reduced within 60 min following the higher dosage of chlordecone. Reduced sexual receptivity occurred more slowly with 50 mg/kg chlordecone (usually within 180 min) and no reduction was seen following 25 mg/kg chlordecone. The reduced sexual behavior after chlordecone treatment preceded the onset of marked chlordecone-induced tremor. A group of rats treated with 75 mg/kg chlordecone was euthanized at the time that behavioral inhibition began to develop. The content of serotonin, norepinephrine, and their principal metabolites was determined by high-performance liquid chromatography of extracts of brain tissue of these animals. In hypothalamus, increases in serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content, and a decrease in the level of norepinephrine (NE), were detected in chlordecone-treated rats relative to matched controls which received vehicle. The content of 5-HT was also increased in preoptic area of chlordecone-treated females. The content of the catecholamine metabolite, 3,4-dihydroxy-phenylacetic acid, was unaffected by chlordecone in either part of brain. These are the first observations of the parallel effects of chlordecone on receptive and proceptive behaviors, and on neurochemistry, in female rats; the results demonstrate short-latency effects of the pesticide treatment on the CNS events that mediate female reproductive behavior. Results of previous studies had led to the suggestion that chlordecone's inhibition of sexual behaviors resulted from its interaction with the intracellular estrogen receptor. However, the rapidity of the inhibition during the period of ongoing sexual behavior makes it unlikely that the inhibition is mediated by the pesticide's action at the intracellular estrogen receptor. Because of the importance of sexual behaviors to reproductive fitness, the current results indicate that nonsteroidal, behavioral mechanisms could contribute to chlordecone's neuroreproductive toxicity.

Analysis of Variance↗
PubMed2002

Social regulation of gonadotropin-releasing hormone.

Behavioral interactions among social animals can regulate both reproductive behavior and fertility. A prime example of socially regulated reproduction occurs in the cichlid fish Haplochromis burtoni, in which interactions between males dynamically regulate gonadal function throughout life. This plasticity is mediated by the brain, where neurons that contain the key reproductive regulatory peptide gonadotropin-releasing hormone (GnRH) change size reversibly depending on male social status. To understand how behavior controls the brain, we manipulated the social system of these fish, quantified their behavior and then assessed neural and physiological changes in the reproductive and stress axes. GnRH gene expression was assessed using molecular probes specific for the three GnRH forms in the brain of H. burtoni. We found that perception of social opportunity to increase status by a male leads to heightened aggressiveness, to increased expression of only one of the three GnRH forms and to increases in size of GnRH-containing neurons and of the gonads. The biological changes characteristic of social ascent happen faster than changes following social descent. Interestingly, behavioral changes show the reverse pattern: aggressive behaviors emerge more slowly in ascending animals than they disappear in descending animals. Although the gonads and GnRH neurons undergo similar changes in female H. burtoni, regulation occurs via endogenous rather than exogenous social signals. Our data show that recognition of social signals by males alters stress levels, which may contribute to the alteration in GnRH gene expression in particular neurons essential for the animal to perform in its new social status.

Aggression↗