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Diurnal rhythms in neural activation in the mesolimbic reward system: critical role of the medial prefrontal cortex
Author(s) -
Baltazar Ricardo M.,
Coolen Lique M.,
Webb Ian C.
Publication year - 2013
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12224
Subject(s) - neuroscience , nucleus accumbens , infralimbic cortex , ventral tegmental area , prefrontal cortex , suprachiasmatic nucleus , basolateral amygdala , zeitgeber , circadian rhythm , psychology , optogenetics , amygdala , central nervous system , dopamine , circadian clock , dopaminergic , cognition
Previous evidence suggests a circadian modulation of drug‐seeking behavior and responsiveness to drugs of abuse. To identify potential mechanisms for rhythmicity in reward, a marker of neural activation (c F os) was examined across the day in the mesolimbic reward system. Rats were perfused at six times during the day [zeitgeber times ( ZT s): 2, 6, 10, 14, 18, and 22], and brains were analysed for c F os and tyrosine hydroxylase ( TH )‐immunoreactive ( IR ) cells. Rhythmic expression of c F os was observed in the nucleus accumbens ( NA c) core and shell, in the medial prefrontal cortex (m PFC ), and in TH ‐ IR and non‐ TH ‐ IR cells in the ventral tegmental area ( VTA ), with peak expression during the late night and nadirs during the late day. No significant rhythmicity was observed in the basolateral amgydala or the dentate gyrus. As the m PFC provides excitatory input to both the NA c and VTA , this region was hypothesised to be a key mediator of rhythmic neural activation in the mesolimbic system. Hence, the effects of excitotoxic m PFC lesions on diurnal rhythms in c F os immunoreactivity at previously observed peak ( ZT 18) and nadir ( ZT 10) times were examined in the NA c and VTA . m PFC lesions encompassing the prelimbic and infralimbic subregions attenuated peak c F os immunoreactivity in the NA c, eliminating the diurnal rhythm, but had no effect on VTA rhythms. These results suggest that rhythmic neural activation in the mesolimbic system may contribute to diurnal rhythms in reward‐related behaviors, and indicate that the m PFC plays a critical role in mediating rhythmic neural activation in the NA c.