Norepinephrine Neurons in the Nucleus of the Solitary Tract Suppress Luteinizing Hormone Secretion in Female Mice.

Stress impairs fertility, at least in part, via inhibition of gonadotropin secretion. Luteinizing hormone (LH) is an important gonadotropin that is released in a pulsatile pattern in males and in females throughout the majority of the ovarian cycle. Several models of stress, including acute metabolic stress, suppress LH pulses via inhibition of neurons in the arcuate nucleus of the hypothalamus that co-express kisspeptin, neurokinin B, and dynorphin (termed KNDy cells) which form the pulse generator. The mechanism for inhibition of KNDy neurons during stress, however, remains a significant outstanding question. Here, we investigated a population of catecholamine neurons in the nucleus of the solitary tract (NTS), marked by expression of the enzyme dopamine beta-hydroxylase (DBH), in female mice. First, we found that a subpopulation of DBH neurons in the NTS are activated (express c-Fos) during metabolic stress. Then, using chemogenetics we determined that activation of these cells is sufficient to suppress LH pulses, augment corticosterone secretion, and induce sickness-like behavior. In subsequent studies, we identified evidence for suppression of KNDy cells (rather than downstream signaling pathways) and determined that the suppression of LH pulses was not dependent on the acute rise in glucocorticoids. Together these data support the hypothesis that DBH cells in the NTS are important for regulation of neuroendocrine and behavioral responses to stress. Significance Statement Stress impairs fertility, at least in part, via inhibition of gonadotropin secretion. The gonadotropin luteinizing hormone (LH) is secreted in a pulsatile pattern in males and females throughout most of the ovarian cycle to support gamete development and sex steroid production in both sexes. Here, we investigated a population of catecholamine neurons in the nucleus of the solitary tract (NTS) for their role in regulation of pulsatile LH secretion. We demonstrate that these neurons are sufficient to suppress pulsatile LH secretion via inhibition of kisspeptin neurons in ovariectomized mice. Moreover, these NTS neurons are also sufficient to augment corticosterone concentrations and induce sickness-like behavior, which raises the possibility that these neurons are important for neuroendocrine and behavioral responses during stress.