Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Sep 2015
Exposure to nicotine increases dopamine receptor content in the mesocorticolimbic pathway of rat dams and offspring during lactation.
Nicotine exposure causes the release of dopamine from the ventral tegmental area (VTA) to the nucleus accumbens (NAc). We have previously shown that maternal exposure to nicotine during lactation causes hyperleptinemia in dams and pups, and leptin is known to decrease dopamine release from the VTA. Here we evaluated whether maternal exposure to nicotine during lactation causes changes in dopamine and leptin signaling pathways at the end of exposure and after 5days of withdrawal in the: VTA, NAc, arcuate nucleus (ARC) and dorsal striatum (DS). ⋯ At weaning (PN21), NIC dams had: lower tyrosine hydroxylase (TH), higher OBRb and SOCS3 contents in VTA; lower TH, higher D1R, D2R and DAT contents in NAc; higher TH content in DS; and higher D2R and SOCS3 contents in ARC. On PN15, NIC offspring had higher D1R, D2R and lower DAT contents in NAc, while on PN21, they had lower DAT in DS, and lower pSTAT3 content in ARC. We evidenced that postnatal nicotine exposure induces relevant changes in the brain reward system of dams and pups, possibly associated with changes in leptinemia and increased offspring anxiety-like behavior.
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Pharmacol. Biochem. Behav. · Sep 2015
Orexin type 1 receptor antagonism in rat locus coeruleus prevents the analgesic effect of intra-LC met-enkephalin microinjection.
Long-term administration of opiates leads to development of tolerance to analgesic effects. This in turn compromise clinical use of these drugs for pain management. Although extensive studies have been conducted, the involved cellular mechanisms are still poorly understood. ⋯ Results indicate that intra-LC microinjection of ME (5μg/100nL) results in development of analgesic tolerance in 3days. Also, OX1R antagonism in LC nucleus significantly prevents the analgesic effect of intra-LC met-enkephalin microinjection. It appears that the analgesic effect of ME in LC neurons is mediated by orexinergic system.