Voluntary ethanol consumption during adolescence elevates enkephalin levels in nucleus accumbens
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
The endogenous opioid system is strongly involved in mediation of ethanol reward and is also an important regulator of stress-induced responses. In many experiments rats are single housed when effects induced by voluntary ethanol drinking are studied. The single housing is potentially stressful. It is therefore important to find out whether single housing can affect endogenous opioids and thereby confound the results in pharmacological studies. The aim of this study was to investigate the effects of adolescent voluntary ethanol drinking on the opioid peptide Met-enkephalin-Arg6Phe7 (MEAP) and examine possible interaction between housing condition and ethanol effects. The rats were either single or pair housed and every cage was provided with special dividers consisting of a clear plastic board with wire mesh panels. Subjects had free access to water and ethanol (20%) or water only, in two hour sessions, three days a week. A specific radioimmunoassay was used for measurement of MEAP in the brain and the pituitary gland. A main effect of ethanol was observed in the nucleus accumbens with lower immunoreactive (ir) MEAP in water drinking single housed rats compared to other groups. Statistical significant correlations were observed between ir MEAP in hypothalamus in pair housed rats and pituitary gland in single housed rats and ethanol intake and also ethanol preference during week 6. These findings point to the importance of distinguish between effects induced by housing and ethanol, respectively, in pharmacological experiments. Furthermore, the results show that adolescent drinking induces changes in the nucleus accumbens that in turn may affect ethanol responses and vulnerability to compulsive intake in adulthood. Increased knowledge in this research area may lead to identification of new pharmaceutical targets and development of individual-based prevention and treatment strategies.
Place, publisher, year, edition, pages
2013. , 21 p.
MEAP, ethanol, nucleus accumbens
Pharmacology and Toxicology
IdentifiersURN: urn:nbn:se:uu:diva-213636OAI: oai:DiVA.org:uu-213636DiVA: diva2:682960
Subject / course
Master of Science Programme in Pharmacy
Nylander, Ingrid, professor
Svensson, Anne-Lie, professor