Brain-pituitary-gonadal axis

Figure 50-9 The regulatory feedback loop of the hypothalamic-pituitary-gonadal axis. Neural and sensory input from the brain elicits the release of Gn-RH. Gn-RH in turn stimulates the synthesis and release of the gonadotropins FSH and LH, which act on the gonads (ovary and testes) to elicit the ripening and ovulation of the ovary and steroidogenesis (estradiol and progesterone) in the female and spermatogenesis and testosterone production in the male. Inhibin formed by the ovaries and testes along with estradiol and testosterone negatively feeds back to the hypothalamic-pituitary axis to modulate Gn-RH, FSH, and LH release.

The platyfish, a small freshwater teleost, has been studied intensively for more than 60 years (Kallman, 1975). Sufficient information has been amassed on its neuroendocrine system and on the hereditary mechanisms that control its age at sexual maturation, to make the platyfish invaluable for the study of the ontogeny, functioning and aging of the brain-pituitary-gonadal (BPG) axis. 

We have begun to explore the nature of olfactory-brain-pituitary-gonad (OBPG) axis function by performing experimental manipulations which, although in their initial phases, further support our contention that a fundamental structural and functional association exists among the components of the OBPG axis. 

Table 9.6 lists the major effects of chronic heavy drinking on body systems. As you can. see, alcohol can be highly toxic to the human body and cause extensive damage to it in a variety of ways. Two prominent body systems that alcohol harms are the brain and the liver. We will look at alcohol s chronic effects on these systems in more detail. Alcohol s chronic effects also extend to human reproductive fimetioning, which has to do with alcohol s altering the fimetioning of the hypothalamic-pituitary-gonadal endocrine axis and with fetal alcohol syndrome (FAS). 

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