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Mechanisms of conjoint failure of the somatotropic and gonadal axes in ageing men.

Endogenous growth hormone (GH) production falls by 50% every 7 years and bioavailable testosterone concentrations decline concomitantly by 12-15% every decade in ageing men. Despite this temporal parallelism, the neuroendocrine bases of the somatopause and gonadopause are not known. This knowledge deficit contrasts with the recent unfolding of new insights into the nature of oestrogen-dependent control of the GH-insulin-like growth factor (IGF)1 axis in pre- and postmenopausal women. The present overview examines the postulate that the pathophysiology of somatopause and gonadopause in ageing men is bidirectionally linked. According to this broader thesis, hyposomatotropism accentuates Leydig cell steroidogenic failure and, conversely, progressive androgen deficiency exacerbates the decline in GH-IGF1 output in ageing.