Dual cerebroventricular and vascular cannulation technique for use in conscious rats

A double cannulation technique which provides access to vascular and cerebroventricular compartments of the unanesthetized rat is described. The technique requires a short surgical preparation time (10–20 min). Plasma levels of luteinizing hormone, follicle stimulating hormone, and prolactin were found to be normal in male rats twenty-four hours after implantation of the cannulas. Plasma hormone levels were also not affected by intraventricular infusion of saline or by repeated blood withdrawal. The application of this technique to research in reproductive physiology and neuroendocrinology is proposed.     

控制性卵巢刺激药物对胎儿安全性的评价

评估不孕症治疗中常用的控制性卵巢刺激(controlled ovarian stimulation,COS)药物对胎儿的安全性极为重要.可利用的数据资料表明,未发现不孕症治疗中常用的COS药物有明显致畸性,并且不会增加出生缺陷率.然而,不孕症本身可能就是形成先天畸形的危险因素之一.综述COS常用药物、药物对胎儿的致畸性...     

The Multiple Birth Epidemic: Revisited

The modern era of infertility treatment was heralded over half a century ago with the introduction of new hormonal drugs that could effectively induce ovarian ovulation. However, it was quickly recognized that the birth of these new “miracle drugs” was associated with a remarkable increase in the incidence of high-order multiple births. Despite the fantastic improvement in our ability to monitor ovarian response during ovulation induction, and our power to control the number of embryos introduced into the womb through IVF, multiple births remain a leading cause of long-term child morbidity among infertility patients. Efforts to prevent what was coined in the 1960s as the “multiple birth epidemic” remain an urgent concern. A new body of research clearly points at our capacity to reduce the risk of multiple births and their associated long term morbidity without diminishing current high success rates of infertility treatment.     

The impact of sleep on gonadotropin secretion

Comparable to the period of pubertal transition, sleep also exerts profound effects on episodic gonadotropin secretion in adult women. During the early follicular phase of the menstrual cycle, a sleep-induced slowing of luteinizing hormone (LH) secretion occurs concurrently with a rise in LHpulse amplitude. A selective increase in opioidergic, but not in dopaminergic or serotoninergk activity may account for this decline in LH pulsatility. In addition, sleep-reversal studies have confirmed that the presence of sleep is essential for the expression of this neuroendocrine function. Since pituitary gonadotropin responsiveness to gonadotropin-releasing hormone (GnRH) is virtually unchanged during sleep, the reasons for the enhanced LH pulse amplitude remain unresolved. This sleep-associated increase in opioidergic activity may be restricted to a hypothalamic site, since opiate blockade does not modify the gonadotropin response to GnRH stimulation. In addition, circadian variability is shown in terms of gonadotropin secretion in regularly cycling women; this may again represent sleep-associated effects on gonadotropin release. Although the physiological importance of sleep-associated neuroendocrine phenomena remains basically unexplained, the observed changes in LH secretory profiles during sleep in adult women suggest close functional links between the endocrine secretion and the rest—activity cycle of the brain.     

Neuroendocrine factors in the initiation of puberty: The emergent role of kisspeptin

Puberty is the end-point of a complex series of developmental events, defined by the dynamic interaction between genetic factors and environmental cues, ultimately leading to the attainment of reproductive capacity. The neuroendocrine basis of puberty has been the subject of extensive investigation in the last decades, and identification of the trigger(s) of puberty onset has drawn considerable attention. In this context, recognition of the fundamental role of kisspeptin (encoded by the KiSS-1 gene) and its receptor GPR54 as major gatekeepers of gonadotropic function in general, and puberty onset in particular, has been a major breakthrough in contemporary Neuroendocrinology. Indeed, during the last 3 years, the so-called KiSS-1/GPR54 system has been substantiated as pivotal regulator of puberty in mammals; the lack of GPR54 signaling being coupled to sexual immaturity (impuberism) in mice and humans. In this review, we will summarize the most salient experimental data (mostly obtained in laboratory animals) demonstrating the key roles of hypothalamic KiSS-1 neurons in the activation of the reproductive axis at puberty, and its regulation by metabolic and, eventually, environmental factors. Whether the KiSS-1 system is the trigger for puberty onset and/or it operates as integrator and effector of up-stream regulatory factors warrants further investigation.     

Photoperiodic modulation of reproductive physiology and behaviour in the cichlid fish Cichlasoma dimerus

Timing of breeding to an optimal season is a requirement for a successful reproductive outcome in seasonally breeding species. Photoperiodic signals are capable of modifying the reproductive behaviour and reproductive systems in several vertebrate species. The cichlid fish Cichlasoma dimerus shows highly organized breeding activities and different social status. The aim of this study is to test whether C. dimerus reproductive behaviour (male aggressive behaviour and female choice) and reproductive physiology (GnRH3 morphometric parameters, pituitary hormones content and organ-somatic indexes) are modulated by photoperiod. Before spawning, dominant pairs were isolated and kept in opposite tanks of 20 l for one week, so they could see each other but not physically interact. Afterwards, a group was exposed for four weeks to a short photoperiod (8 h light:16 h dark) (short photoperiod exposed animals: SP) while another group was exposed to a long photoperiod (14 h light:10 h dark) (long photoperiod exposed animals: LP). Temperature was maintained constant. Behavioural experiments showed that male aggression related to territory selection and its defence is reduced in SP males. Further, SP females were never chosen. At the brain level we demonstrated that GnRH3 neuronal optical density of staining was reduced. Finally, at the pituitary level we showed that SP males showed low levels of β-LH, PRL and GH in the pituitary, and that SP females showed no significant differences in the pituitary content of any hormone. Taken all together these results suggest that in C. dimerus the photoperiod is a relevant environmental cue related to reproductive behaviour and physiology.