Microinjection of urocortin 2 into the dorsal raphe nucleus activates serotonergic neurons and increases extracellular serotonin in the basolateral amygdala.
The intra dorsal raphe nucleus (DRN) administration of corticotropin releasing hormone (CRF) inhibits serotonergic (5-HT) activity in this structure, an effect blocked by antagonists selective for the type 1 CRF receptor (CRF1). The DRN has a high density of the type 2 receptor (CRF2), and so the present experiments explored the impact of CRF2 activation within the DRN on 5-HT function. The intra-DRN administration of the selective CRF2 agonist urocortin 2 (Ucn 2) dose dependently increased 5-HT efflux in the basolateral amygdala, a projection region of the DRN. Intra-DRN Ucn 2 also increased c-fos expression in labeled 5-HT neurons. Both of these effects of Ucn 2 were completely blocked by intra-DRN antisauvagine-30 (ASV-30), a relatively selective CRF2 antagonist. These data suggest that CRF1 and CRF2 activation within the DRN affect 5-HT neurons in opponent fashion. Implications of these results for understanding the behavioral effects of CRF and other CRF-like ligands are discussed.
Amat
J
J
Department of Psychology and Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309-0345, USA. amat@psych.colorado.edu
Tamblyn
J P
JP
Paul
E D
ED
Bland
S T
ST
Amat
P
P
Foster
A C
AC
Watkins
L R
LR
Maier
S F
SF
D000679:Amygdala / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002452:Cell Count / Q000379:methods; D003346:Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D003952:Diagnostic Imaging / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005110:Extracellular Space / Q000187:drug effects; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D017551:Microdialysis / Q000379:methods; D008845:Microinjections / Q000379:methods; D010446:Peptide Fragments / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011903:Raphe Nuclei / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D013997:Time Factors; D054832:Urocortins
D010446:Peptide Fragments; D016760:Proto-Oncogene Proteins c-fos; D054832:Urocortins; C116607:antisauvagine 30; D012701:Serotonin; D003346:Corticotropin-Releasing Hormone