TY - JOUR
T1 - Median and Dorsal Raphe Serotonergic Neurons Control Moderate Versus Compulsive Cocaine Intake
AU - Verheij, Michel M.M.
AU - Contet, Candice
AU - Karel, Peter
AU - Latour, Judith
AU - van der Doelen, Rick H.A.
AU - Geenen, Bram
AU - van Hulten, Josephus A.
AU - Meyer, Francisca
AU - Kozicz, Tamas
AU - George, Olivier
AU - Koob, George F.
AU - Homberg, Judith R.
N1 - Publisher Copyright:
© 2017 Society of Biological Psychiatry
PY - 2018/6/15
Y1 - 2018/6/15
N2 - Background: Reduced expression of the serotonin transporter (SERT) promotes anxiety and cocaine intake in both humans and rats. We tested the hypothesis that median raphe nucleus (MRN) and dorsal raphe nucleus (DRN) serotonergic projections differentially mediate these phenotypes. Methods: We used virally mediated RNA interference to locally downregulate SERT expression and compared the results with those of constitutive SERT knockout. Rats were allowed either short access (ShA) (1 hour) or long access (LgA) (6 hours) to cocaine self-administration to model moderate versus compulsive-like cocaine taking. Results: SERT knockdown in the MRN increased cocaine intake selectively under ShA conditions and, like ShA cocaine self-administration, reduced corticotropin-releasing factor (CRF) immunodensity in the paraventricular nucleus of the hypothalamus. In contrast, SERT knockdown in the DRN increased cocaine intake selectively under LgA conditions and, like LgA cocaine self-administration, reduced CRF immunodensity in the central nucleus of the amygdala. SERT knockdown in the MRN or DRN produced anxiety-like behavior, as did withdrawal from ShA or LgA cocaine self-administration. The phenotype of SERT knockout rats was a summation of the phenotypes generated by MRN- and DRN-specific SERT knockdown. Conclusions: Our results highlight a differential role of serotonergic projections arising from the MRN and DRN in the regulation of cocaine intake. We propose that a cocaine-induced shift from MRN-driven serotonergic control of CRF levels in the hypothalamus to DRN-driven serotonergic control of CRF levels in the amygdala may contribute to the transition from moderate to compulsive intake of cocaine.
AB - Background: Reduced expression of the serotonin transporter (SERT) promotes anxiety and cocaine intake in both humans and rats. We tested the hypothesis that median raphe nucleus (MRN) and dorsal raphe nucleus (DRN) serotonergic projections differentially mediate these phenotypes. Methods: We used virally mediated RNA interference to locally downregulate SERT expression and compared the results with those of constitutive SERT knockout. Rats were allowed either short access (ShA) (1 hour) or long access (LgA) (6 hours) to cocaine self-administration to model moderate versus compulsive-like cocaine taking. Results: SERT knockdown in the MRN increased cocaine intake selectively under ShA conditions and, like ShA cocaine self-administration, reduced corticotropin-releasing factor (CRF) immunodensity in the paraventricular nucleus of the hypothalamus. In contrast, SERT knockdown in the DRN increased cocaine intake selectively under LgA conditions and, like LgA cocaine self-administration, reduced CRF immunodensity in the central nucleus of the amygdala. SERT knockdown in the MRN or DRN produced anxiety-like behavior, as did withdrawal from ShA or LgA cocaine self-administration. The phenotype of SERT knockout rats was a summation of the phenotypes generated by MRN- and DRN-specific SERT knockdown. Conclusions: Our results highlight a differential role of serotonergic projections arising from the MRN and DRN in the regulation of cocaine intake. We propose that a cocaine-induced shift from MRN-driven serotonergic control of CRF levels in the hypothalamus to DRN-driven serotonergic control of CRF levels in the amygdala may contribute to the transition from moderate to compulsive intake of cocaine.
KW - Anxiety-related behavior
KW - CRF
KW - Corticotropin-releasing factor
KW - Dorsal raphe nucleus
KW - Gene silencing
KW - Knockdown
KW - Knockout
KW - Long access to cocaine self-administration
KW - Median raphe nucleus
KW - SERT
KW - Serotonin transporter
KW - Short access to cocaine self-administration
UR - http://www.scopus.com/inward/record.url?scp=85040543541&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85040543541&partnerID=8YFLogxK
U2 - 10.1016/j.biopsych.2017.10.031
DO - 10.1016/j.biopsych.2017.10.031
M3 - Article
C2 - 29357981
AN - SCOPUS:85040543541
SN - 0006-3223
VL - 83
SP - 1024
EP - 1035
JO - Biological psychiatry
JF - Biological psychiatry
IS - 12
ER -