SAT606 Comparison Of Psychosocial And Immune/Inflammatory Stress On Luteinizing Hormone Pulsatile Secretion

Abstract

Abstract Disclosure: J. Jang: None. M.J. Kreisman: None. K.M. Breen Church: None. Stress induces a physiological response in the body to return to the homeostatic state. It is recognized that many stress types impair reproduction, but the mechanisms conveying inhibition may be distinct and stressor-dependent. Our research aims to understand how stress inhibits the neuroendocrine mechanisms controlling the pulsatile release of luteinizing hormone (LH). This is especially important because pulsatile LH is pivotal to reproductive health in males and females. Immune/inflammatory stressors such as lipopolysaccharides (LPS) cause an inflammatory response, producing peripheral cytokines that can signal to the brain in distinct ways compared to the neural mechanisms employed in response to psychosocial stress. However, how LPS disrupts the neural mechanisms involved in gonadotropin pulsatility is still unknown. Here, we compared the alteration in LH pulses in response to psychosocial restraint stress or immune/inflammatory LPS stress and sought to understand stress-specific regulation of the upstream targets controlling LH synthesis and secretion. Our initial observations demonstrated, in ovariectomized (OVX) female mice, that restraint stress elicited suppression rapidly, within 30 minutes; yet, the response to LPS was delayed, occurring approximately 90 minutes from injection. Therefore, we investigated the prolonged response of the stressors on LH pulses, observing LH pulse profiles 90 minutes to 180 minutes after the initiation of stress. Restraint stress significantly suppressed mean LH, resulting from a suppression of pulse frequency. LPS injected intraperitoneal (IP, 1.5 ug/g) also significantly suppressed mean LH. In contrast to restraint stress, LPS induced a reduction in both frequency as well as LH pulse amplitude. We conducted two follow-up experiments to investigate the lowered LH pulse amplitude during immune/inflammatory stress. The first study assessed hypothalamic kisspeptin gene expression and pituitary LHβ and GnRH receptor expression, in LPS versus restraint animals, to test whether altered gene transcription in LPS animals resulted in lowered LH secretion. The results of this experiment are still pending. The second study tested the LH response to a single bolus of GnRH or kisspeptin. Interestingly, we found equivalent LH increases, to either agonist, in saline versus LPS-treated animals. Collectively, these data indicate that both restraint and immune/inflammatory stress inhibit LH pulse frequency. However, the endogenous LH pulse profiles suggest an additional stressor-specific mechanism that lowers pulsatile LH during immune/inflammatory stress via LPS. Identification of stress pathways that alter endocrine hormones is critical as it allows for the development of therapeutics and medications to treat endocrine disorders. Presentation: Saturday, June 17, 2023