5-HT denervation of the adult rat prefrontal cortex induces changes in the expression of α4 and α7 nicotinic acetylcholine receptor subtypes

Abstract

IntroductionNicotinic acetylcholine receptors (nAChRs) are widely expressed throughout several brain regions. Formation of the α4β2 and α7 subtypes in particular is involved in the organisation of different types of memory. Furthermore, due to their location, these receptors can control the release of various types of neurotransmitters and contribute to synaptic plasticity. MethodsRats were divided into three groups, an experimental group (E), sham-operated group (S) and an intact group (T). In group E, stereotactic guidance was used to induce a chemical lesion with 1μg/μL of 5,7-dihydroxytryptamine (5,7-DHT) in the anteroventral part of the dorsal raphe nucleus (DRN). In the sham-operated group (S), animals underwent surgery including delivery of the same excipient solution to the same site. The intact group (T) received no treatment whatsoever. Twenty days after surgery, animals in all groups were euthanised by decapitation to evaluate the expression of α4 and α7 nAChRs by means of molecular biology techniques. Results5-HT denervation of the rat prefrontal cortex (PFC) differentially modified the expression of α4 and α7 receptors: while α4 receptor expression increased, α7 expression decreased. ConclusionExpression differences observed between the two subtypes may be due to their separate locations. The α4 subtype is found in postsynaptic locations and may be related to adaptive changes in postsynaptic cells, while the location of α7 is presynaptic. This explains why the lesion and the elimination of 5-HT fibres in the CPF would cause a decrease in α7 expression.