Chapman A, Gonzales G, Burrowes W R, Assanah P, Iannone B, Leung M K, Stefano G B
Cell Mol Neurobiol. 1984 Jun;4(2):143-55. doi: 10.1007/BF00711001.
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.
在贻贝和家蝇中，老年动物的高亲和力结合位点密度显著低于幼年动物，而低亲和力位点密度保持不变。在贻贝中，老年动物中估计的甲硫氨酸脑啡肽和甲硫氨酸脑啡肽-精氨酸6-苯丙氨酸7水平显著高于幼年动物。在家蝇中，只能测定甲硫氨酸脑啡肽水平，且老年动物中的该水平也更高。高亲和力结合位点密度的降低以及内源性脑啡肽水平的相应升高表明存在与衰老过程相关的阿片类代偿机制。在贻贝中，已证明随着年龄增长，施加阿片类药物后神经节内多巴胺水平会下降。此外，阿片类药物对多巴胺刺激的腺苷酸环化酶活性的抑制作用在老年动物中也会降低。在家蝇中，阿片类结合密度的性别差异随年龄减小。
