Lipotropin, melanotropin and endorphin: in vivo catabolism and entry into cerebrospinal fluid.
Anesthetized rabbits were given intravenous injections of either beta-lipotropin (beta-LPH), beta-melanotropin (beta-MSH) or beta-endorphin. The postinjection concentrations of these peptides in plasma and cerebrospinal fluid (CSF) were measured by radioimmunoassay (RIA). The plasma disappearance half-times were 13.7 min for beta-LPH, 5.1 min for beta-MSH, and 4.8 min for beta-endorphin. Circulating beta-LPH is cleaved to peptides tentatively identified as gamma-LPH and beta-endorphin. Each of these peptides appeared in the CSF within 2 min postinjection. The maximum CSF to plasma ratios were 0.08 for beta-LPH, 1.48 for beta-MSH,and 0.23 for beta-endorphin.
D000818:Animals; D004723:Endorphins / Q000134:cerebrospinal fluid / Q000378:metabolism*; D006207:Half-Life; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000134:cerebrospinal fluid / Q000378:metabolism*; D011817:Rabbits; D011863:Radioimmunoassay; D008083:beta-Lipotropin / Q000134:cerebrospinal fluid / Q000378:metabolism*
D004723:Endorphins; D009074:Melanocyte-Stimulating Hormones; D008083:beta-Lipotropin