Manuela Eisenhardt1, Anita C Hansson, Rainer Spanagel, Ainhoa Bilbao. 1. Behavioral Genetics Research Group, Central Institute of Mental Health, University of Heidelberg, Mannheim, Germany; Institute of Psychopharmacology, Central Institute of Mental Health, University of Heidelberg, Mannheim, Germany.
Abstract
BACKGROUND: One of the most commonly used approaches to induce ethanol (EtOH) dependence in rodents is EtOH vapor inhalation. This procedure requires the co-administration of pyrazole-an inhibitor of the alcohol dehydrogenase-to obtain stable blood EtOH concentrations (BECs) during the entire induction course. However, pyrazole can produce unwanted side effects. Our goal was to obtain EtOH-dependent mice without pyrazole and to study their behavioral and molecular postdependent phenotype. In particular, we were interested in alterations in the corticotrophin-releasing hormone (CRH) and receptor (CRHR1 and CRHR2) system as a prominent role of CRH in driving the postdependent state via actions in the central extended amygdala (CeA) has been demonstrated in rats but not in postdependent mice. METHODS: We established an alternative model of chronic intermittent EtOH (CIE) inhalation without the use of pyrazole in C57BL/6N mice. Our CIE exposure protocol involved 8 cycles. One cycle consisted of 8 hours with EtOH inhalation and 8 hours without EtOH. We then examined withdrawal symptoms. After 2 weeks of abstinence, we studied relapse, reinstatement of EtOH-seeking, and stress-induced EtOH self-administration. We also did transcriptional analysis of components of the CRH system during CIE, protracted abstinence, and after stress-induced EtOH self-administration. RESULTS: CIE exposure without pyrazole resulted in reproducible BECs during the induction procedure. Mice showed strong withdrawal scores during 4 to 12 hours after the last CIE cycle and enhanced stress-induced EtOH self-administration. This postdependent phenotype during abstinence was accompanied by enhanced Crh and Crhr1 transcripts but no change in Crhr2 transcripts in the CeA. Cue-induced EtOH-seeking behavior and relapse (alcohol deprivation effect) were not affected by the inhalation procedure. CONCLUSIONS: We have established a CIE inhalation protocol without pyrazole in mice and showed excessive EtOH self-administration under mild stress and enhanced CRH/CRHR1 signaling in the CeA.
BACKGROUND: One of the most commonly used approaches to induce ethanol (EtOH) dependence in rodents is EtOH vapor inhalation. This procedure requires the co-administration of pyrazole-an inhibitor of the alcohol dehydrogenase-to obtain stable blood EtOH concentrations (BECs) during the entire induction course. However, pyrazole can produce unwanted side effects. Our goal was to obtain EtOH-dependent mice without pyrazole and to study their behavioral and molecular postdependent phenotype. In particular, we were interested in alterations in the corticotrophin-releasing hormone (CRH) and receptor (CRHR1 and CRHR2) system as a prominent role of CRH in driving the postdependent state via actions in the central extended amygdala (CeA) has been demonstrated in rats but not in postdependent mice. METHODS: We established an alternative model of chronic intermittent EtOH (CIE) inhalation without the use of pyrazole in C57BL/6N mice. Our CIE exposure protocol involved 8 cycles. One cycle consisted of 8 hours with EtOH inhalation and 8 hours without EtOH. We then examined withdrawal symptoms. After 2 weeks of abstinence, we studied relapse, reinstatement of EtOH-seeking, and stress-induced EtOH self-administration. We also did transcriptional analysis of components of the CRH system during CIE, protracted abstinence, and after stress-induced EtOH self-administration. RESULTS:CIE exposure without pyrazole resulted in reproducible BECs during the induction procedure. Mice showed strong withdrawal scores during 4 to 12 hours after the last CIE cycle and enhanced stress-induced EtOH self-administration. This postdependent phenotype during abstinence was accompanied by enhanced Crh and Crhr1 transcripts but no change in Crhr2 transcripts in the CeA. Cue-induced EtOH-seeking behavior and relapse (alcohol deprivation effect) were not affected by the inhalation procedure. CONCLUSIONS: We have established a CIE inhalation protocol without pyrazole in mice and showed excessive EtOH self-administration under mild stress and enhanced CRH/CRHR1 signaling in the CeA.
Authors: Johannes Knabbe; Jil Protzmann; Niklas Schneider; Michael Berger; Dominik Dannehl; Shoupeng Wei; Christopher Strahle; Michèle Tegtmeier; Astha Jaiswal; Hongwei Zheng; Marcus Krüger; Karl Rohr; Rainer Spanagel; Ainhoa Bilbao; Maren Engelhardt; Henrike Scholz; Sidney B Cambridge Journal: Proc Natl Acad Sci U S A Date: 2022-06-14 Impact factor: 12.779
Authors: Sonia Aroni; Rosa A M Marino; Kasey S Girven; James M Irving; Joseph F Cheer; Dennis R Sparta Journal: Neuropharmacology Date: 2021-03-17 Impact factor: 5.250