Low testosterone — driven by hypothalamic GnRH suppression, Leydig cell dysfunction, elevated SHBG, or impaired LH pulsatility — produces fatigue, reduced libido, body composition decline, mood disorders, and metabolic dysfunction. Peptide research offers upstream interventions that stimulate endogenous testosterone production rather than replacing it exogenously.
1. Kisspeptin — GnRH / LH Pulsatility Restoration
Kisspeptin is the master regulator of the HPG axis — controlling GnRH secretion and the LH pulse that stimulates Leydig cell testosterone production. Declining kisspeptin signaling is increasingly recognized as a primary driver of age-related testosterone decline. Kisspeptin administration directly restores LH pulsatility and testosterone output without suppressing natural axis function.
Dosing Protocol: 50–100 mcg SubQ 2–3x per week. Clinical trials use 0.3–10 nmol/kg IV; SubQ 50–100 mcg extrapolates from published dose-response data.
2. Ipamorelin + CJC-1295 — GH/Testosterone Cross-Talk
GH and testosterone are synergistic — GH optimizes the metabolic environment for testosterone production, reduces visceral fat (which converts testosterone to estrogen via aromatase), and supports the pituitary-gonadal axis through IGF-1 mediated mechanisms. Restoring GH pulsatility often produces measurable testosterone improvement.
Dosing Protocol: 200–300 mcg Ipamorelin + 100–200 mcg CJC-1295 SubQ before bed. 5 on/2 off. Cycle: 12–16 weeks.
3. Sermorelin — GHRH Axis / Endocrine Environment
Sermorelin provides sustained GHRH receptor stimulation, improving GH output through the natural hypothalamic pathway. Better GH status improves body composition, reduces adipose aromatization of testosterone, and supports the overall anabolic hormonal environment in which testosterone functions most effectively.
Dosing Protocol: 200–300 mcg SubQ before bed. 5 on/2 off. Can be rotated with or combined with Ipamorelin for comprehensive GHRH+GHRP coverage.
4. HCG — Direct Leydig Cell Stimulation
Human Chorionic Gonadotropin (HCG) mimics LH at the Leydig cell level — directly stimulating intratesticular testosterone production. It maintains testicular size and testosterone production independent of pituitary LH output, making it valuable for men with secondary hypogonadism or pituitary-level HPG suppression.
Dosing Protocol: 250–500 IU SubQ 2–3x per week. Standard testosterone optimization adjunct dose. Monitor estradiol as HCG can increase aromatization.
Kisspeptin restores the hypothalamic GnRH drive that initiates the entire testosterone production cascade. Ipamorelin/CJC and Sermorelin optimize the GH axis that metabolically supports testosterone function. HCG provides direct Leydig cell stimulation — bypassing the HPG axis entirely to maintain intratesticular testosterone production regardless of pituitary status.
Research Use Only. All information on this page is for educational purposes only and is not medical advice. PepSherpa does not sell peptides. Consult a licensed healthcare provider before making any health decisions. Many of the studies cited are preclinical (animal/in-vitro).