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5‐HT 2C receptor activation inhibits appetitive and consummatory components of feeding and increases brain c‐ fos immunoreactivity in mice
Author(s) -
Somerville Elizabeth M.,
Horwood Julia M.,
Lee Michelle D.,
Kennett Guy A.,
Clifton Peter G.
Publication year - 2007
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/j.1460-9568.2007.05567.x
Subject(s) - serotonergic , agonist , 5 ht receptor , receptor , basolateral amygdala , medicine , endocrinology , serotonin , receptor antagonist , amygdala , antagonist , 5 ht1a receptor , chemistry , neuroscience , biology
5‐Hydroxytryptamine (5‐HT) 2C and 5‐HT 1B receptors are implicated in the inhibitory modulation of feeding behaviour. However, their respective, and possibly different, roles have not been clearly identified because of a lack of selective 5‐HT 2C receptor agonists. Here, using the putative, selective 5‐HT 2C receptor agonist VER23779, we show that its effects on feeding are fully reversed by pretreatment with a selective 5‐HT 2C receptor antagonist, but unaffected by pretreatment with either a 5‐HT 1B or a 5‐HT 2A receptor antagonist. In mice eating a palatable mash, feeding ends earlier, inactivity is increased but the behavioural satiety sequence is preserved. In a second‐order schedule of reinforcement with an initial, non‐food‐reinforced appetitive phase, VER23779 produces a much greater relative reduction in appetitive responding than the 5‐HT 1B receptor agonist CP‐94,253. Increased c‐ fos immunoreactivity patterns following VER23779 also differ from those described for CP‐94,253, in particular showing strong activation of the basolateral amygdala. The different behavioural consequences of 5‐HT 2C and 5‐HT 1B receptor activation may relate to the patterns of c‐ fos immunoreactivity. In particular, the basolateral amygdala may have a role in maintaining response in the appetitive phase of the second‐order schedule and also be susceptible to serotonergic modulation through activation of 5‐HT 2C receptors.