Neuronal basis of reproductive dysfunctions associated with diet and alcohol: From the womb to adulthood.

The theory that individuals are born as tabula rasa and that their knowledge comes from experience and perception is no longer true. Studies suggest that experience is gained as early as in the mother's womb. Moreover, environmental stressors like alcohol or inadequate diet can affect physiological systems such as the hypothalmic-pituitary-gonadal (HPG) axis. The effects of these stressors can manifest as alterations in sexual development and adult reproductive functions. In this review, we consider and compare evidence from animal models and human studies demonstrating the role of environmental stressors (alcohol and under- or overnutrition) on the HPG axis. We review the role of alcohol and inadequate diet in prenatal reproductive system programming and consider specific candidate neurons in the adult hypothalamus through which reproductive function is being regulated. Finally, we review evidence from animal studies on the role that alcohol and diet play in fertility and reproductive disorders. We conclude that in order to better understand reproductive failure in animals and humans we need to consider in utero development and pay more attention to early life experience when searching for the origins of reproductive diseases.

Insulin: its role in the central control of reproduction.

Insulin has long been recognized as a key regulator of energy homeostasis via its actions at the level of the brain, but in addition, plays a role in regulating neural control of reproduction. In this review, we consider and compare evidence from animal models demonstrating a role for insulin for physiological control of reproduction by effects on GnRH/LH secretion. We also review the role that insulin plays in prenatal programming of adult reproduction, and consider specific candidate neurons in the adult hypothalamus by which insulin may act to regulate reproductive function. Finally, we review clinical evidence of the role that insulin may play in adult human fertility and reproductive disorders. Overall, while insulin appears to have a significant impact on reproductive neuroendocrine function, there are many unanswered questions regarding its precise sites and mechanisms of action, and their impact on developing and adult reproductive neuroendocrine function.

Locomotor performance of sand lizards (Lacerta agilis): effects of predatory pressure and parasite load.

Locomotor performance affects foraging efficiency, predator avoidance and consequently fitness. Agility and speed determine the animal's social status and reflect its condition. In this study, we test how predatory pressure and parasite load influences locomotor performance of wild specimens of the sand lizard Lacerta agilis. Animals were chased on a 2-metre racetrack. Lizards with autotomy ran significantly faster than lizards with an intact tail, but there was no significant difference in running speed between individuals with fresh caudal autotomy and regenerated tails. Parasite presence and load, age and sex had no significant effect on speed. Our results indicate that autotomy either alters locomotory behaviour or that individuals with autotomised tails were those that previously survived contact with predators, and therefore represented a subgroup of the fastest individuals. Therefore, in general, predatory pressure but not parasites affected locomotor performance in lizards.