Disappearance of the mu-opiate receptor patches in the rat neostriatum following lesioning of the ipsilateral nigrostriatal dopamine pathway with 1-methyl-4-phenylpyridinium ion (MPP+): restoration by embryonic nigral dopamine grafts.
Using in vitro autoradiography, this study examined the binding of the selective mu-opiate receptor radiolabelled ligand, [3H]Tyr-D-Ala-Gly-Me-Phe-Gly-ol ([3H]DAGO) to the striatal sections of rats with long-term unilateral lesions of the nigrostriatal dopamine (DA) pathway induced by 1-methyl-4-phenylpyridinium ion (MPP+) and in animals bearing embryonic DA grafts implanted into the DA-depleted striatum. In the ipsilateral striatum of MPP+-lesioned animals, there was a complete disappearance of the mu-opiate receptor patches as well as the subcallosal streak. The normal pattern of mu-binding sites in the patches reappeared following reinnervation of the DA-depleted striatum by the DA-grafts. These findings suggest that mu-opiate receptor patches in the striatum are localised on nigrostriatal DA afferent terminals. However, it is possible that trans-synaptic or postsynaptic changes also contribute to the profound alterations in striatal mu-opiate binding patterns revealed in this study.
Sirinathsinghji
D J
DJ
Department of Neuroendocrinology, AFRC Institute of Animal Physiology and Genetics Research, Cambridge, U.K.
Dunnett
S B
SB
D015655:1-Methyl-4-phenylpyridinium / Q000494:pharmacology*; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism* / Q000502:physiology; D004298:Dopamine / Q000502:physiology*; D004622:Embryo, Mammalian; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000378:metabolism*; D005260:Female; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017450:Receptors, Opioid, mu; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology* / Q000637:transplantation
D004745:Enkephalins; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D015655:1-Methyl-4-phenylpyridinium; D004298:Dopamine