title: Multiple immunoreactive forms of met- and leu-enkephalin in fetal and neonatal rat brain and in rat gut.
abstract: We have used radioimmunoassays with carboxyl-specific antisera to study the development of met- and leu-enkephalin in rat brain and gut from 13-days of fetal age through adulthood. Fractionation of HCl extracts of fetal and neonatal brain tissues by HPLC revealed the presence of immunoreactive forms other than met- and leu-enkephalin. For example, HPLC separation of extracts of 16-day fetal brain yielded two peaks of leu-enkephalin-like immunoreactivity. One emerged at the position of leu-enkephalin, the other eluted with about one-third the retention time. There were four peaks of met-enkephalin-like immunoreactivity, one with the retention time characteristic of met-enkephalin, the others with shorter retention times. In contrast, all of the met-enkephalin-like immunoreactivity in adult brain eluted with the retention time characteristic of authentic met-enkephalin and all of the leu-enkephalin-like immunoreactivity eluted in the position of authentic leu-enkephalin. Multiple immunoreactive forms of met- and leu-enkephalin were found in extracts of both fetal and adult gut tissues.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D001921:Brain / Q000276:immunology*; D002851:Chromatography, High Pressure Liquid; D004743:Enkephalin, Leucine / Q000276:immunology*; D004744:Enkephalin, Methionine / Q000276:immunology*; D005260:Female; D005333:Fetus / Q000276:immunology*; D007422:Intestines / Q000276:immunology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine