title: Alterations in high-affinity binding characteristics and levels of opioids in invertebrate ganglia during aging: evidence for an opioid compensatory mechanism.
abstract: In Mytilus and Leucophaea the high-affinity binding site density is significantly lower in old animals than in young animals, whereas the low-affinity site density remains unchanged. In Mytilus the estimated met-enkephalin and met-enkephalin-Arg6-Phe7 levels are significantly higher in old than in young animals. In Leucophaea only the met-enkephalin level can be determined, and it is also higher in old animals. The decrease in the high-affinity binding site density and the corresponding increase in endogenous enkephalin levels suggest the existence of an opioid compensatory mechanism associated with the aging process. In Mytilus there is a demonstrated decrease with age in intraganglionic dopamine levels in response to applied opiates. In addition, the inhibition of dopamine-stimulated adenylate cyclase activity by opiates also decreases in older animals. In Leucophaea the sex difference in opioid binding densities diminishes with age.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000375:Aging; D000818:Animals; D049872:Bivalvia; D004298:Dopamine / Q000032:analysis; D004723:Endorphins / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D005048:Etorphine / Q000378:metabolism; D005724:Ganglia / Q000378:metabolism*; D007313:Insecta; D009270:Naloxone / Q000378:metabolism; D012737:Sex Factors
chemical_list: D004723:Endorphins; D009270:Naloxone; D005048:Etorphine; D004744:Enkephalin, Methionine; C022118:enkephalinamide-Met, Ala(2)-; D000262:Adenylyl Cyclases; D004298:Dopamine