Transient Postnatal Gonadal Activation and Growth Velocity in Infancy

Kuopio University Hospital, the Pediatric Research Foundation, the Finnish National Graduate School of Clinical Investigation, the Emil Aaltonen Foundation, the Jalmari and Rauha Ahokas Foundation, the Sigrid Jusélius Foundation, the Academy of Finland, and the Finnish Medical Foundation

Testicular Steroidogenesis

Testosterone is the major androgen in circulation in male humans, produced primarily in the Leydig cells of the testis. Biosynthesis of testosterone from cholesteroloccursviaaseriesofenzymaticreactions.Testosteronemaybefurther metabolized into a more potent androgen, dihydrotestosterone. In recent years an alternate pathway of dihydrotestosterone biosynthesis without using testosterone as a precursor has emerged. Majority of classically studied effects of androgens are thought to be mediated via nuclear receptor-dependent long-term transcriptional effects, but there also exist membrane receptor-based effects of androgens which are being uncovered from recent studies that may explain rapid effects of androgens in many cases. In this chapter we are describing the biosynthesis, mechanism of action, and therapeutic effects of testosterone and related androgens

The gentle art of saying NO: how nitric oxide gets things done in the hypothalamus

International audienceThe chemical signalling molecule nitric oxide (NO), which freely diffuses through aqueous and lipid environments, subserves an array of functions in the mammalian central nervous system, such as the regulation of synaptic plasticity, blood flow and neurohormone secretion. In this Review, we consider the cellular and molecular mechanisms by which NO evokes short-term and long-term changes in neuronal activity. We also highlight recent studies showing that discrete populations of neurons that synthesize NO in the hypothalamus constitute integrative systems that support life by relaying metabolic and gonadal signals to the neuroendocrine brain, and thus gate the onset of puberty and adult fertility. The putative involvement and therapeutic potential of NO in the pathophysiology of brain diseases, for which hormonal imbalances during postnatal development could be risk factors, is also discussed