Can chronic stress suppress GnRH pulsatility and LH signaling?

Chronic activation of the hypothalamic-pituitary-adrenal (HPA) axis under stress disrupts reproductive function by suppressing the hypothalamic-pituitary-gonadal (HPG) axis. This neuroendocrine inhibition occurs through both central hypothalamic and direct pituitary mechanisms.

Central hypothalamic suppression

• Upstream pulse generator disruption: Stress signals like corticotropin-releasing hormone (CRH) and elevated glucocorticoids act on the arcuate nucleus to suppress the kisspeptin/KNDy (kisspeptin/neurokinin B/dynorphin) neuronal network. This impairs the primary pulse generator that drives GnRH pulsatility.
• Direct GnRH repression: Glucocorticoids bind to glucocorticoid receptors (GR) on GnRH neurons, directly repressing GnRH gene transcription and promoter activity through interactions with negative glucocorticoid responsive elements and transcription factors like Oct-1. Simultaneously, stress activates inhibitory pathways, including gonadotropin-inhibitory hormone (GnIH/RFRP-3) and central GABAergic circuits.

Downstream pituitary impacts

• Impaired LH pulsatility: Because hypothalamic GnRH pulsatility drives pituitary gonadotrope function, a reduction in GnRH pulse frequency and amplitude directly decreases downstream pituitary LH pulse frequency and amplitude.
• Direct gonadotrope inhibition: Elevated glucocorticoids bind to type II GRs on pituitary gonadotropes to blunt intracellular GnRH receptor signaling. This process modulates calcium/calmodulin-dependent protein kinase II (CaMKII) pathways and inhibits the arachidonic acid liberation required for LH exocytosis.
• Transcriptional repression: Activated GRs are recruited directly to the LHβ promoter, repressing GnRH-induced LHβ subunit gene expression and selectively lowering LH pulse amplitude.

Bottom line

• Chronic stress-axis activation suppresses downstream LH signaling via a dual-site mechanism: centrally by disrupting the hypothalamic kisspeptin-GnRH pulse generator, and peripherally by directly blunting pituitary gonadotrope responsiveness and LHβ gene transcription.