Stress and the Reproductive System Chapter 36 Stress and the Reproductive System © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 36.1 Effect of insulin-induced hypoglycemic stress on hypothalamic multiunit activity (MUA) volleys and on serum levels of LH and cortisol in a rhesus monkey during the early follicular phase of the menstrual cycle. Note the interruption of GnRH pulse generator activity coincident with the fall in blood sugar and its recovery despite the continued elevated levels of cortisol. Reprinted with permission from Chen et al.107 © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition

FIGURE 36.2 Putative circuitry leading to the suppression of pulsatile GnRH/gonadotropin secretion by immunologic stress (intravenous injection of bacterial LPS), psychogenic stress (confining the animal inside a restraint tube), or metabolic stress (insulin-induced hypoglycemia). Circuits in part are those directly inferred from the experiments of Lin et al.136 in which either the medial or the central nucleus of the amygdala was chemically lesioned or the effects of stress on Fos expression in these nuclei were measured. The circuits leading to LH pulse suppression by hypoglycemia are unaffected by lesions in either amygdalar location, and the data supporting their routings are derived from other studies as cited in the text. The graphs in the lower part of the figure show the temporary interruption of episodic LH secretion after LPS, restraint or hypoglycemic stress in nonlesioned animals. Modification from Merriam and Koenig.156 © 2015, Elsevier, Inc., Plant and Zeleznik, Knobil and Neill's Physiology of Reproduction, Fourth Edition