PT  - JOURNAL ARTICLE
AU  - Gregory O. Hjelmstad
AU  - Yanfang Xia
AU  - Elyssa B. Margolis
AU  - Howard L. Fields
TI  - Opioid Modulation of Ventral Pallidal Afferents to Ventral Tegmental Area Neurons
AID  - 10.1523/JNEUROSCI.0178-13.2013
DP  - 2013 Apr 10
TA  - The Journal of Neuroscience
PG  - 6454--6459
VI  - 33
IP  - 15
4099  - http://www.jneurosci.org/content/33/15/6454.short
4100  - http://www.jneurosci.org/content/33/15/6454.full
SO  - J. Neurosci.2013 Apr 10; 33
AB  - Activation of mu opioid receptors within the ventral tegmental area (VTA) can produce reward through the inhibition of GABAergic inputs. GABAergic neurons in the ventral pallidum (VP) provide a major input to VTA neurons. To determine the specific VTA neuronal targets of VP afferents and their sensitivity to mu opioid receptor agonists, we virally expressed channel rhodopsin (ChR2) in rat VP neurons and optogenetically activated their terminals in the VTA. Light activation of VP neuron terminals elicited GABAergic IPSCs in both dopamine (DA) and non-DA VTA neurons, and these IPSCs were inhibited by the mu opioid receptor agonist DAMGO. In addition, using a fluorescent retrograde marker to identify VTA-projecting VP neurons, we found them to be hyperpolarized by DAMGO. Both of these actions decrease GABAergic input onto VTA neurons, revealing two mechanisms by which endogenous or exogenous opioids can activate VTA neurons, including DA neurons.