Altered sucrose self-administration following injection of melanocortin receptor agonists and antagonists into the ventral tegmental area

作者：Shanmugarajah Laranci; Dunigan Anna I; Frantz Kyle J; Roseberry Aaron G^*

来源：Psychopharmacology, 2017, 234(11): 1683-1692.

DOI：10.1007/s00213-017-4570-4

• alpha MSH
• Dopamine
• Self-administration
• Melanocortin
• Feeding
• MC3R
• VTA

Rationale and objectives Alpha-melanocyte stimulating hormone (alpha MSH) and agouti-related protein (AgRP) are antagonistic neuropeptides that play an important role in the control of feeding and body weight through their central actions on the melanocortin-3 and melanocortin-4 receptors. Increasing evidence indicates that aMSH and AgRP can interact with the mesolimbic dopamine system to regulate feeding as well as other behaviors. For example, we have shown previously that injection of melanocortin receptor agonists and antagonists into the ventral tegmental area (VTA) alters both normal home-cage feeding and the intake of sucrose solutions, but it remains unknown whether aMSH and AgRP can also act in the VTA to affect reward-related feeding.
Methods We tested whether injection of the melanocortin receptor agonist, MTII, or the melanocortin receptor antagonist, SHU9119, directly into the VTA affected operant responding maintained by sucrose pellets in self-administration assays. Results Injection of MTII into the VTA decreased operant responding maintained by sucrose pellets on both fixed ratio and progressive ratio schedules of reinforcement, whereas SHU9119 increased operant responding under fixed ratio, but not progressive ratio schedules. MTII also increased and SHU9119 decreased 24-h home-cage food intake.
Conclusions This study demonstrates that aMSH and AgRP act in the VTA to affect sucrose self-administration. Thus, it adds critical information to the growing literature showing that in addition to their well-characterized role in controlling "need-based" feeding, aMSH and AgRP can also act on the mesolimbic dopamine system to control reward-related behavior.

• 出版日期2017-6