title: Intracameral administration of alpha-MSH increases intraocular pressure in rabbits.
abstract: A growing body of evidence suggests that neural peptides may induce important modulations on vegative and motor functions of the eye. The present study was designed to evaluate the effect of intracameral (I.C.) administration of alpha-melanocyte-stimulating hormone (alpha-MSH) and several other ocular peptides on intraocular pressure (IOP) in rabbits. alpha-MSH (5 micrograms) produced a significant and prolonged unilateral increase of IOP. This effect of I.C. alpha-MSH was dose-dependent (ED50 = 2.5 micrograms). Structure-activity studies revealed that equimolar doses of beta-MSH and gamma-MSH, unlike alpha-MSH, were totally ineffective. In addition, the structurally unrelated peptides beta-endorphin, thyrotropin-releasing hormone (TRH) and gonadotropin-releasing hormone (Gn-RH) did not affect IOP, when tested in a dose equimolar to 5 micrograms of alpha-MSH. These results confirm and extend previous observations, suggesting that alpha-MSH may be an important factor involved in regulation of IOP.
mesh_terms: D000818:Animals; D000867:Anterior Chamber; D004305:Dose-Response Relationship, Drug; D007267:Injections; D007429:Intraocular Pressure / Q000187:drug effects*; D009074:Melanocyte-Stimulating Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology; D011817:Rabbits; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D010455:Peptides; D009074:Melanocyte-Stimulating Hormones