Knowledge
Biology
GLP-1, GIP, GH secretagogues, melanocortins, copper peptides, tissue-repair biology, mitochondrial biology.
5 questions
What is GLP-1 and why do so many drugs target it?
GLP-1 is a peptide hormone secreted after eating that stimulates insulin release, suppresses appetite, and slows gastric emptying. Long-acting synthetic analogues (semaglutide, tirzepatide) are the most impactful metabolic drugs of the last decade.
What is GIP?
GIP is the other major incretin hormone besides GLP-1. Long considered clinically less important, GIP receptor agonism turned out to be a critical component of tirzepatide's effectiveness.
What is glucagon and why is it in retatrutide?
Glucagon is the counter-regulatory hormone to insulin. Pharmacologically-sustained glucagon receptor activation increases fat oxidation and energy expenditure — effects that complement GLP-1/GIP in retatrutide's triple-agonist design.
What are GH secretagogues?
GH secretagogues are peptides that stimulate the pituitary to release growth hormone. They fall into two families: GHRH-analogues (Sermorelin, CJC-1295, Tesamorelin) and ghrelin-mimetics (Ipamorelin, older GHRPs).
What are melanocortins?
Melanocortins are a family of peptides derived from proopiomelanocortin (POMC) that act on five receptors (MC1R–MC5R) governing pigmentation, appetite, sexual response, and inflammation.