Acute Stress, Hypothalamic-Hypophyseal-Gonadal Axis and Testicular Function – A Review

The fact that the stress response affects testicular function in several animal species, has been established for several decades. The aim of the present review was to describe how the mechanisms involved in the acute stress response affect directly or indirectly the testicular function at different levels. Both neuroendocrine axes linked to the stress response, i.e., the sympathetic-adrenomedullar (SAM) axis and the hypothalamic-hypophyseal-adrenal (HHA) axis, affect the functioning of the hypothalamus-hypophyseal-gonadal (HHG) axis. Furthermore, both axes affect testicular function directly. Several reports support the concept that, in general terms, the HHA axis (as well as the hormones belonging to it) inhibits the HHG axis and also has direct effects on testicular function. The information regarding the effects of the SAM axis either on the HHG axis or as direct effects on testicular function are contradictory, and depends on whether the studies were performed in vivo or in vitro. Nevertheless, in general, stimulative effects are reported by the SAM axis. Both hormonal axes linked to the stress response exert direct effects on testicular function, on Leydig, Sertoli, myoid, and germ cells.