Changes in the processing of pro-dynorphin end products in the substantia nigra during neonatal development.
The steady-state levels of pro-dynorphin-related end products were measured in the substantia nigra of the rat at neonatal day 0, 7, 14 and in the adult. At neonatal day 0 there was evidence that pro-dynorphin had undergone posttranslational processing to yield dynorphin A-related products, dynorphin B(1-13) and alpha-neo-endorphin. At this stage the molar ratio of dynorphin A(1-17) to dynorphin A(1-8) was 1:1 and a peak of 4 kilodalton dynorphin A-related immunoreactivity was detected. By neonatal day 7 the molar ratio of dynorphin A(1-17) to dynorphin A(1-8) resembled the adult processing pattern for the substantia nigra. The rapid maturation of the pro-dynorphin system in the substantia nigra is in contrast to the development of the pro-dynorphin system in the posterior pituitary where adult-like processing patterns are not observed until neonatal day 21 (11). Pro-enkephalin products have also been detected in the substantia nigra of the rat (15). At neonatal day 0 and neonatal day 7 the molar ratio of Met-enkephalin to Leu-enkephalin was 4:1. However, in the adult the molar ratio of Met-enkephalin to Leu-enkephalin was 1.4:1 in this terminal field. These results suggest that in the adult or perhaps late in neonatal development some pro-dynorphin end products undergo further proteolytic cleavage to yield Leu-enkephalin.
Sei
C A
CA
University of Denver, Department of Biological Sciences, CO 80208.
Dores
R M
RM
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004743:Enkephalin, Leucine / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013378:Substantia Nigra / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*
D004745:Enkephalins; D011498:Protein Precursors; D004743:Enkephalin, Leucine; C033660:preproenkephalin