RT Journal Article
SR Electronic
T1 Retrograde Opioid Signaling Regulates Glutamatergic Transmission in the Hypothalamus
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7349
OP 7358
DO 10.1523/JNEUROSCI.0381-09.2009
VO 29
IS 22
A1 Karl J. Iremonger
A1 Jaideep S. Bains
YR 2009
UL http://www.jneurosci.org/content/29/22/7349.abstract
AB Opioid signaling in the CNS is critical for controlling cellular excitability, yet the conditions under which endogenous opioid peptides are released and the precise mechanisms by which they affect synaptic transmission remain poorly understood. The opioid peptide dynorphin is present in the soma and dendrites of vasopressin neurons in the hypothalamus and dynamically controls the excitability of these cells in vivo. Here, we show that dynorphin is released from dendritic vesicles in response to postsynaptic activity and acts in a retrograde manner to inhibit excitatory synaptic transmission. This inhibition, which requires the activation of κ-opioid receptors, results from a reduction in presynaptic release of glutamate vesicles. The opioid inhibition is downstream of Ca2+ entry and is likely mediated by a direct modulation of presynaptic fusion machinery. These findings demonstrate that neurons may self-regulate their excitability through the dendritic release of opioids to inhibit excitatory synaptic transmission.