Activation of mu opioid receptors in the striatum differentially augments methamphetamine-induced gene expression and enhances stereotypic behavior

Authors


Address correspondence and reprint requests to Kristen Ashley Horner, PhD, Division of Basic Medical Sciences, Mercer University School of Medicine, 1550 College Street, Macon, GA 31207, USA. E-mail: horner_ka@mercer.edu

Abstract

J. Neurochem. (2012) 120, 779–794.

Abstract

Mu opioid receptors are densely expressed in the patch compartment of striatum and contribute to methamphetamine-induced patch-enhanced gene expression and stereotypy. To further elucidate the role of mu opioid receptor activation in these phenomena, we examined whether activation of mu opioid receptors would enhance methamphetamine-induced stereotypy and prodynorphin, c-fos, arc and zif/268 expression in the patch and/or matrix compartments of striatum, as well as the impact of mu opioid receptor activation on the relationship between patch-enhanced gene expression and stereotypy. Male Sprague–Dawley rats were intrastriatally infused with d-Ala(2)-N-Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO; 1 μg/μL), treated with methamphetamine (0.5 mg/kg) and killed at 45 min or 2 h later. DAMGO augmented methamphetamine-induced zif/268 mRNA expression in the patch and matrix compartments, while prodynorphin expression was increased in the dorsolateral patch compartment. DAMGO pre-treatment did not affect methamphetamine-induced arc and c-fos expression. DAMGO enhanced methamphetamine-induced stereotypy and resulted in greater patch versus matrix expression of prodynorphin in the dorsolateral striatum, leading to a negative correlation between the two. These findings indicate that mu opioid receptors contribute to methamphetamine-induced stereotypy, but can differentially influence the genomic responses to methamphetamine. These data also suggest that prodynorphin may offset the overstimulation of striatal neurons by methamphetamine.

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