| First Author | Lemos JC | Year | 2012 |
| Journal | J Neurosci | Volume | 32 |
| Issue | 36 | Pages | 12325-36 |
| PubMed ID | 22956823 | Mgi Jnum | J:187681 |
| Mgi Id | MGI:5437782 | Doi | 10.1523/JNEUROSCI.2053-12.2012 |
| Citation | Lemos JC, et al. (2012) Repeated Stress Dysregulates kappa-Opioid Receptor Signaling in the Dorsal Raphe through a p38alpha MAPK-Dependent Mechanism. J Neurosci 32(36):12325-36 |
| abstractText | Repeated stress releases dynorphins and causes subsequent activation of kappa-opioid receptors (KORs) in limbic brain regions. The serotonergic dorsal raphe nucleus (DRN) has previously been found to be an important site of action for the dysphoric effects of dynorphin-kappa-opioid receptor system activation during stress-evoked behaviors, and KOR-induced activation of p38alpha mitogen-activated protein kinase (MAPK) in serotonergic neurons was found to be a critical mediator of the aversive properties of stress. Yet, how dynorphins and KORs functionally regulate the excitability of serotonergic DRN neurons both in adaptive and pathological stress states is poorly understood. Here we report that acute KOR activation by the selective agonist U69,593 [(+)-(5alpha,7alpha,8beta)-N-methyl-N-[7-(1-pyrrolidinyl)-1-oxaspiro[4.5]dec-8-yl ]benzeneacetamide] inhibits serotonergic neuronal excitability within the DRN through both presynaptic inhibition of excitatory synaptic transmission and postsynaptic activation of G-protein-gated inwardly rectifying potassium channels (GIRKs) electrophysiologically recorded in brain slices. C57BL/6 mice subjected to repeated swim, stress sessions had significantly reduced KOR-mediated GIRK currents recorded in serotonergic neurons in DRN postsynaptically, without significantly affecting presynaptic KOR-mediated regulation of excitatory transmission. This effect was blocked by genetic excision of p38alpha MAPK selectively from serotonergic neurons. An increase in phospho-immunoreactivity suggests that this functional dysregulation may be a consequence of tyrosine phosphorylation of GIRK (K(IR)3.1) channels. These data elucidate a mechanism for stress-induced dysregulation of the excitability of neurons in the DRN and identify a functional target of stress-induced p38alpha MAPK activation that may underlie some of the negative effects of pathological stress exposure. |
