Hypothalamus-pituitary-gonad axis

The impact of sirolimus on hormone concentrations involved in the hypothalamus-pituitary-gonad axis has been investigated in 132 male heart transplant recipients... 

Cadmium can act on the reproductive system by either directly affecting the gonads and accessory organs, or indirectly via interference with the hypothalamus-pituitary-gonadal axis. 

Fig. 1. Hormone secretion and control of the hypothalamic-pituitary-gonadal axis. Plus and minus signs indicate stimulation and inhibition respectively. In both male and female animals the dominant feedback effect of gonadal steroids on the hypothalamic-pituitary axis is inhibitory. The only major exception is in the female in which a rapid FSH-induced increase in the concentration of oestradiol triggers a large increase of the secretion of LH to induce ovulation. Note that LHRH secreted by the hypothalamus is carried directly to the pituitary gland without entering the peripheral circulation. Since the pituitary and gonadal hormones are secreted into the peripheral blood stream the functional response to hormone agonists or antagonists may be assessed by simple measurements of circulating hormone concentration ).

Fig. 2. Gonadotrophin releasing hormone (GnRH) released in pulses by the hypothalamus stimulates pituitary production and secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH). The hypothalamic-pituitary—gonadal (H-P-G) axis is affected by a variety of external hormones and external factors.

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