AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 2 429-R434, Copyright © 1989 by American Physiological Society
Posttranslational processing of opioid pro-opiomelanocortin products in piglets
I. R. Moss, J. G. Inman and C. A. Slaughter
Department of Pediatrics, University of Texas, Southwestern Medical Center, Dallas.
We have measured levels of beta-lipotropin, beta-endorphin, and
N-acetyl-beta-endorphin in the plasma, cerebrospinal fluid (CSF), and
caudal medullary brain containing the respiratory-related portion of the
nucleus tractus solitarius (NTS) of 2.5 +/- 1.0- (SD) and 38.2 +/-
3.7-day-old naive uninstrumented piglets. Time of day, ambient atmosphere,
temperature, handling, sound, light, and nutritional status were kept
constant. Experimental procedure included decapitation and rapid
collection, processing, and freezing of tissues until analysis by
radioimmunoassay. Young, compared with older piglets, have higher measured
levels of beta-lipotropin in the plasma and CSF and of
N-acetyl-beta-endorphin in all three body compartments. Although measured
levels of beta-endorphin-like immunoreactivity are also higher in the
plasma and CSF of the young group, the calculated level of beta-endorphin
is higher only in the CSF. In the NTS, both the measured and calculated
active endorphin appear higher in the older group, but this difference is
not significant. Excess beta-endorphin in the CSF of neonates may explain
the relative immaturity of their respiratory functions at birth.
