Chronic nicotine‐induced changes in gene expression of delta and kappa‐opioid receptors and their endogenous ligands in the mesocorticolimbic system of the rat. Issue 9 (29th May 2017)

• Record Type: Journal Article
• Authors: Ugur, Muzeyyen; Kaya, Egemen; Gozen, Oguz; Koylu, Ersin O.; Kanit, Lutfiye; Keser, Aysegul; Balkan, Burcu
• Is Part Of: Synapse. Volume 71:Issue 9(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-05-29
• Subjects: nicotine -- opioid receptors -- prodynorphin -- proenkephalin -- reward; Synapses -- Periodicals; 612
• DOI: 10.1002/syn.21985
• Languages: English
• ISSNs: 0887-4476

Abstract

Abstract: Delta and kappa opioid receptors (DOR and KOR, respectively) and their endogenous ligands, proenkephalin (PENK) and prodynorphin (PDYN)‐derived opioid peptides are proposed as important mediators of nicotine reward. This study investigated the regulatory effect of chronic nicotine treatment on the gene expression of DOR, KOR, PENK and PDYN in the mesocorticolimbic system. Three groups of rats were injected subcutaneously with nicotine at doses of 0.2, 0.4, or 0.6 mg/kg/day for 6 days. Rats were decapitated 1 hr after the last dose on day six, as this timing coincides with increased dopamine release in the mesocorticolimbic system. mRNA levels in the ventral tegmental area (VTA), lateral hypothalamic area (LHA), amygdala (AMG), dorsal striatum (DST), nucleus accumbens, and medial prefrontal cortex were measured by quantitative real‐time PCR. Our results showed that nicotine upregulated DOR mRNA in the VTA at all of the doses employed, in the AMG at the 0.4 and 0.6 mg/kg doses, and in the DST at the 0.4 mg/kg dose. Conversely, PDYN mRNA was reduced in the LHA with 0.6 mg/kg nicotine and in the AMG with 0.4 mg/kg nicotine. KOR mRNA was also decreased in the DST with 0.6 mg/kg nicotine. Nicotine did not regulate PENK mRNA in any brain region studied. Abstract : Chronic subcutaneous nicotine administration regulated prodynorphin (PDYN), kappa (KOR) and delta (DOR) opioid receptor mRNA expression in the rat mesocorticolimbic system. Proenkephalin (PENK) mRNA was not altered in any of the brain regions studied: ventral tegmental area (VTA), lateral hypothalamus (LHA), amygdala (AMG), nucleus accumbens (NAc), dorsal striatum (DST), medial prefrontal cortex (mPFC).