Kisspeptin as a Behavioral Hormone.

Successful reproduction is dependent not only on hormonal endocrine responses but also on suitable partner selection, copulatory acts, as well as associated emotional, behavioral, and cognitive processes many of which are supported by the limbic system. The reproductive hormone kisspeptin (encoded by the KISS1/kiss1 gene) is now recognized as the key orchestrator of the reproductive axis. In addition to the hypothalamus, prominent kisspeptin neuronal populations have been identified throughout limbic and paralimbic brain regions across an assortment of species. In this review, we detail the emerging roles of kisspeptin signaling in the broader aspects of behavioral, emotional, and cognitive control. Recent studies from zebrafish through humans have provided new molecular and neural insights into the complex role of kisspeptin in interpreting olfactory and auditory cues to govern sexual partner preference, in regulating copulatory behaviors and in influencing mood and emotions. Furthermore, emerging roles for kisspeptin in facilitating memory and learning are also discussed. To this end, these findings shed new light onto the importance of kisspeptin signaling, while informing the pharmacological development of kisspeptin as a potential therapeutic strategy for individuals suffering from associated reproductive, emotional, and cognitive disorders.

Environmentally relevant exposure of 17α-ethinylestradiol impairs spawning and reproductive behavior in the brackish medaka Oryzias melastigma.

We assessed the effects of 17α-ethinylestradiol (EE2) on spawning and reproductive behavior of the brackish medaka Oryzias melastigma at environmental concentrations. Breeding pairs were exposed to EE2 at either lower concentrations (0, 1, and 10 ng/L) or higher concentrations (0, 50, and 100 ng/L) for 14 days. Swimming performance and reproductive behavior (following, dancing, and copulation) of the males were analyzed at the end of exposure. Additionally, gonad histology was conducted in the males in the higher EE2 experiment. We found that spawning was significantly inhibited in the 50-100 ng/L EE2 groups. Swimming performance was not affected in all groups. Dancing and copulation were significantly suppressed in the 50-100 ng/L groups. No effect was observed in testis histology in the 50-100 ng/L groups. Our data suggests that reproductive behavior of O. melastigma can be utilized as a behavioral endpoint for ecotoxicology studies of endocrine disruptors in estuarine/marine environments.

Alcoholic marriage: later start, sooner end.

BACKGROUND: Although associations between drinking behavior and marital status are well documented, timing of marital transitions as a function of alcohol use or disorder has received limited empirical attention. METHODS: We examine the relationship between lifetime history of alcohol dependence (AD) and timing and survival of first marriages in a sample of 3,575 female and 1,845 male adult Australian twins born mostly between 1940 and 1964. Survival analyses were conducted using Cox proportional hazards regression models. RESULTS: Results indicate moderate delays in marriage associated with AD for both women and men. Among ever-married respondents, AD was strongly predictive of early separation, with similar effects observed for women and men. Heritable sources of covariation were also documented. For women, genetic influences shared between early-onset AD and marital timing were found. Genetic influences shared between AD and marital survival were observed for women without regard to onset and for men with later-onset AD. CONCLUSIONS: Results confirm the importance of AD as a predictor of both timing and survival of first marriages, with genetic influences contributing to observed associations.

Investigating intergenerational differences in human PCB exposure due to variable emissions and reproductive behaviors.

BACKGROUND: Reproductive behaviors--such as age of childbearing, parity, and breast-feeding prevalence--have changed over the same historical time period as emissions of polychlorinated biphenyls (PCB) and may produce intergenerational differences in human PCB exposure. OBJECTIVES: Our goal in this study was to estimate prenatal, postnatal, and lifetime PCB exposures for women at different ages according to year of birth, and to evaluate the impact of reproductive characteristics on intergenerational differences in exposure. METHODS: We used the time-variant mechanistic model CoZMoMAN to calculate human bioaccumulation of PCBs, assuming both hypothetical constant and realistic time-variant emissions. RESULTS: Although exposure primarily depends on when an individual was born relative to the emission history of PCBs, reproductive behaviors can have a significant impact. Our model suggests that a mother's reproductive history has a greater influence on the prenatal and postnatal exposures of her children than it does on her own cumulative lifetime exposure. In particular, a child's birth order appears to have a strong influence on their prenatal exposure, whereas postnatal exposure is determined by the type of milk (formula or breast milk) fed to the infant. CONCLUSIONS: Prenatal PCB exposure appears to be delayed relative to the time of PCB emissions, particularly among those born after the PCB production phaseout. Consequently, the health repercussions of environmental PCBs can be expected to persist for several decades, despite bans on their production for > 40 years.

Diversity of actions of GnRHs mediated by ligand-induced selective signaling.

Geoffrey Wingfield Harris' demonstration of hypothalamic hormones regulating pituitary function led to their structural identification and therapeutic utilization in a wide spectrum of diseases. Amongst these, Gonadotropin Releasing Hormone (GnRH) and its analogs are widely employed in modulating gonadotropin and sex steroid secretion to treat infertility, precocious puberty and many hormone-dependent diseases including endometriosis, uterine fibroids and prostatic cancer. While these effects are all mediated via modulation of the pituitary gonadotrope GnRH receptor and the G(q) signaling pathway, it has become increasingly apparent that GnRH regulates many extrapituitary cells in the nervous system and periphery. This review focuses on two such examples, namely GnRH analog effects on reproductive behaviors and GnRH analog effects on the inhibition of cancer cell growth. For both effects the relative activities of a range of GnRH analogs is distinctly different from their effects on the pituitary gonadotrope and different signaling pathways are utilized. As there is only a single functional GnRH receptor type in man we have proposed that the GnRH receptor can assume different conformations which have different selectivity for GnRH analogs and intracellular signaling proteins complexes. This ligand-induced selective-signaling recruits certain pathways while by-passing others and has implications in developing more selective GnRH analogs for highly specific therapeutic intervention.