John Yeomans, PhD, Department of Psychology, University of Toronto
Title: Mesopontine Control Opioid-Induced Locomotion and Rewards
Brain & Behaviour Seminar Series 2013-2014Abstract:
Opioids induce rewarding effects in rodents via GABA, dopamine, cholinergic and glutamate neurons in the midbrain and pons. We propose a new theory of how these neurons coordinate using anatomical, pharmacogenetic and optogenetic data in mice. Rostromedial tegmental (RMTg) GABA neurons are the main site where opioids act via inhibitory mu-opioid receptors, facilitated by inhibitory GABA-A and M4 muscarinic receptors. Mesopontine cholinergic neurons facilitate dopamine output via excitatory M5 muscarinic receptors, and at the same time inhibit RMTg neurons via M4 receptors. Mesopontine cholinergic and glutamate neurons that mediate dopamine-dependent and dopamine-independent rewards are inhibited by RMTg in strongly aversive states, including food deprivation and opioid withdrawal.
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