title: The C-fragment of beta-lipotropin: an endogenous neuroleptic or antipsychotogen?
abstract: Microinjection of the C-fragment (also called beta-endorphin), which is amino acid sequence 61-91 of the endogenous pituitary hormone, beta-lipotropin (beta-LPH), in the periaqueductal gray of the rat resulted in profound sedation and catalepsy, while microinjection of smaller fragments-that is, methionine-enkephalin [sequence beta-LPH-(61-65)] and its related pentapeptide, leucine enkephalin, and alpha-endorphin [sequence beta-LPH-(61-76)] resulted in attenuated forms of this behavior. This indicates that the C-fragment is an important neuromodulator of the central nervous system. The similarity of this behavior to that seen after systemic administration to experimental animals of exogenous neuroleptics suggests that a disturbance in the bioavailability of this neuropeptide to receptor sites in brain-perhaps due to lack of enzymatic cleavage from the circulating parent hormone, beta-lipotropin--may be an etiological factor in those psychopathological states for which the exogenous neuroleptics exert an ameliorative influence.
mesh_terms: D000698:Analgesia; D000818:Animals; D001921:Brain / Q000187:drug effects*; D002375:Catalepsy / Q000139:chemically induced*; D002535:Cerebral Aqueduct; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006993:Hypnotics and Sedatives; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D009842:Oligopeptides; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid; D012018:Reflex / Q000187:drug effects*; D013329:Structure-Activity Relationship; D008083:beta-Lipotropin
chemical_list: D006993:Hypnotics and Sedatives; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D010455:Peptides; D011957:Receptors, Opioid; D009270:Naloxone; D008083:beta-Lipotropin