RT Journal Article
SR Electronic
T1 Regulation of GABA and Glutamate Release from Proopiomelanocortin Neuron Terminals in Intact Hypothalamic Networks
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 4042
OP 4048
DO 10.1523/JNEUROSCI.6032-11.2012
VO 32
IS 12
A1 Matthew S. Dicken
A1 Ryan E. Tooker
A1 Shane T. Hentges
YR 2012
UL http://www.jneurosci.org/content/32/12/4042.abstract
AB Hypothalamic proopiomelanocortin (POMC) neurons and their peptide products mediate important aspects of energy balance, analgesia, and reward. In addition to peptide products, there is evidence that POMC neurons can also express the amino acid transmitters GABA and glutamate, suggesting these neurons may acutely inhibit or activate downstream neurons. However, the release of amino acid transmitters from POMC neurons has not been thoroughly investigated in an intact system. In the present study, the light-activated cation channel channelrhodopsin-2 (ChR2) was used to selectively evoke transmitter release from POMC neurons. Whole-cell electrophysiologic recordings were made in brain slices taken from POMC-Cre transgenic mice that had been injected with a viral vector containing a floxed ChR2 sequence. Brief pulses of blue light depolarized POMC-ChR2 neurons and induced the release of GABA and glutamate onto unidentified neurons within the arcuate nucleus, as well as onto other POMC neurons. To determine whether the release of GABA and glutamate from POMC terminals can be readily modulated, opioid and GABAB receptor agonists were applied. Agonists for μ- and κ-, but not δ-opioid receptors inhibited transmitter release from POMC neurons, as did the GABAB receptor agonist baclofen. This regulation indicates that opioids and GABA released from POMC neurons may act at presynaptic receptors on POMC terminals in an autoregulatory manner to limit continued transmission. The results show that, in addition to the relatively slow and long-lasting actions of peptides, POMC neurons can rapidly affect the activity of downstream neurons via GABA and glutamate release.