title: Spinal cord dynorphin precursor intermediates decline during late gestation.
abstract: This laboratory has previously reported that the maternal opioid analgesia associated with pregnancy and parturition is mediated, at least in part, by a maternal spinal cord dynorphin/kappa opioid system. This analgesia is accompanied by an increase in dynorphin peptides (1-17 and 1-8) in the lumbar spinal cord. Levels of trypsin-generated arginine6-leucine-enkephalin (Leu-Enk-Arg)-immunoreactive determinants were also determined and used to reflect the content of dynorphin precursor intermediates. In spinal tissue, the amount of dynorphin A (1-17) contained in the form of precursor is, at a minimum, 10-fold higher than the content of mature dynorphin A (1-17) or dynorphin (1-8). During gestational day 22, the content of dynorphin precursor is reduced significantly (approximately 50%). The decline in the magnitude of dynorphin precursor intermediates in the spinal cord of pregnant rats vastly exceeds the magnitude of increase in the content of dynorphin peptides (1-17 and 1-8). This difference can best be explained by postulating a corresponding increase in the rate of release of spinal cord dynorphin (1-17). It is suggested that enhanced processing of dynorphin precursor intermediates represents the initial biochemical level of adaptation of spinal dynorphin neurons to increased demands of pregnancy.
authors.affiliation: Department of Biochemistry, State University of New York Health Science Center at Brooklyn 11203, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Medina
authors.forename: D
authors.initials: D
authors.lastname: Gupta
authors.forename: A R
authors.initials: AR
authors.lastname: Gintzler
mesh_terms: D000698:Analgesia; D000818:Animals; D004399:Dynorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism; D005260:Female; D008970:Molecular Weight; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism*; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism
chemical_list: D011498:Protein Precursors; D004743:Enkephalin, Leucine; D004399:Dynorphins; C026768:enkephalin-Leu, Arg(6)-; D014357:Trypsin