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D 1 and D 2 receptor regulation of preproenkephalin and preprodynorphin mRNA in rat striatum following acute injection of amphetamine or methamphetamine
Author(s) -
Wang John Q.,
McGinty Jacqueline F.
Publication year - 1996
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/(sici)1098-2396(199602)22:2<114::aid-syn4>3.0.co;2-g
Subject(s) - eticlopride , nucleus accumbens , methamphetamine , meth , striatum , amphetamine , sch 23390 , pharmacology , chemistry , medicine , in situ hybridization , basal ganglia , receptor antagonist , endocrinology , dopamine receptor d2 , antagonist , receptor , dopamine , messenger rna , central nervous system , biochemistry , monomer , organic chemistry , acrylate , gene , polymer
Our previous work has demonstrated a dose‐dependent induction of striatalpreprodynorphin (PPD) in response to a single injection of the psychostimulants amphetamine(AMPH) or methamphetamine (METH). In the present study, dose‐response effects of acuteadministration of these stimulants on preproenkephalin (PPE) mRNA expression in the ratstriatum were investigated with quantitative in situ hybridization histochemistry 3 h afterinjection. Acute AMPH or METH at equimolar doses (3.75, 7.5, 15, and 30 μmol/kg)significantly increased PPE mRNA expression in dorsal (caudoputamen), but not ventral(nucleus accumbens), striatum in a dose‐dependent fashion. In addition, the role ofD 1 and D 2 dopamine receptors in mediating AMPH‐ andMETH‐stimulated PPE and PPD expression was also evaluated by using subtype‐specificantagonists. Pretreatment of rats with SCH 23390 (0.1 mg/kg, i.p.), a selectiveD 1 receptor antagonist, completely blocked acute AMPH (21 μmol/kg,i.p.)‐ or METH (21 μmol/kg, i.p.)‐induced PPE as well as PPD mRNA expression in thecaudoputamen. Pretreatment with eticlopride (0.5 mg/kg, i.p.), a selective D 2 receptor antagonist, also blocked PPD induction by the two stimulants, but PPE induction wasunaffected. Furthermore, SCH 23390 decreased, and eticlopride elevated, constitutive PPEmRNA levels in the caudoputamen. Neither antagonist had a significant effect on the basallevel of PPE or PPD mRNA in the nucleus accumbens. These results demonstrate a cleardose‐related responsiveness of PPE gene expression in striatal neurons in response to acuteadministration of amphetamines, although the intensity of the response is far less than that forstriatal PPD. Furthermore, both D 1 and D 2 subtypes of dopaminereceptors mediate AMPH‐ and METH‐stimulated striatal PPD mRNA expression, whereasD 1 receptor activation alone mediates amphetamine‐stimulated PPE mRNAexpression in the rat striatum. © 1996 Wiley‐Liss, Inc.