Distinct presynaptic control of dopamine release in striosomal- and matrix-enriched areas of the rat striatum by selective agonists of NK1, NK2, and NK3 tachykinin receptors.
Using a sensitive in vitro microperfusion method, the effects of selective and potent agonists of NK1, NK2, and NK3 tachykinin receptors ([Pro9]SP, ([Lys5,MeLeu9,Nle10]NKA-(4-10), and [Pro7]NKB, respectively) on the presynaptic control of dopamine release were investigated in striosomal-enriched (area rich in [3H]naloxone binding sites) and matrix-enriched areas of the rat striatum. Marked differences could be demonstrated as follows: (i) when used at 0.1 microM, the NK1 agonist stimulated the release of [3H]dopamine continuously synthesized from [3H]tyrosine in both compartments, while the NK2 and NK3 agonists enhanced the release of [3H]dopamine only in the matrix; (ii) the stimulatory effect of the NK3 agonist was less pronounced than those of the NK1 and NK2 agonists; (iii) the NK1 agonist-evoked responses were tetrodotoxin (1 microM) sensitive, while those of the NK2 and NK3 agonists were, respectively, partially and totally tetrodotoxin resistant; (iv) specific receptors are involved in these responses since the stimulatory effects of the NK1 and NK2 agonists were, respectively, blocked by potent antagonists of NK1 (RP-67580; 1 microM) and NK2 (SR-48968; 1 microM) receptors, while these antagonists did not affect the NK3 agonist-evoked response; (v) the indirect stimulatory effect of the NK1 agonist was partially reduced under local blockade of cholinergic transmission in the matrix but not in the striosomal-enriched area. Interestingly, this study also revealed mismatches between autoradiographic data and receptor-mediated responses, since NK2 binding sites could not be observed in the striatum while NK3 but not NK1 binding sites were visualized in the striosomal-enriched area.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D015288:Neurokinin A / Q000502:physiology; D015287:Neurokinin B / Q000502:physiology; D010393:Pempidine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017981:Receptors, Neurotransmitter / Q000187:drug effects*; D018039:Receptors, Tachykinin; D013373:Substance P / Q000502:physiology; D013570:Synaptic Membranes / Q000378:metabolism*; D009435:Synaptic Transmission; D013779:Tetrodotoxin / Q000494:pharmacology
D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D013373:Substance P; D013779:Tetrodotoxin; D001285:Atropine; D015288:Neurokinin A; D015287:Neurokinin B; D010393:Pempidine; D004298:Dopamine