Scientific Glossary

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GnRH is released in pulses from the hypothalamus, stimulating pituitary gonadotroph cells to release LH and FSH. LH triggers testosterone production (in males: Leydig cells; in females: corpus luteum) and FSH drives sperm and follicle development. Critically, continuous (non-pulsatile) GnRH receptor stimulation causes receptor downregulation and hormone suppression — this is exploited therapeutically with GnRH agonists for prostate cancer. PT-141 (bremelanotide) acts upstream via melanocortin receptors to influence sexual arousal pathways.

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Pulsatile secretion is physiologically important because continuous receptor stimulation leads to desensitization. The pituitary gland releases GH in 6-12 pulses per day (largest pulse shortly after sleep onset). GnRH must be pulsatile to maintain gonadotropin secretion — continuous GnRH agonist exposure paradoxically suppresses LH/FSH. Research into GHRH and GHRP combinations aims to amplify these natural GH pulses rather than create continuous supraphysiological exposure. Mimicking natural pulsatile patterns is a key design principle in hormone research.