S. Davis et al., LONG-LASTING EFFECTS OF AN ACUTE STRESS ON THE NEUROCHEMISTRY AND FUNCTION OF 5-HYDROXYTRYPTAMINERGIC NEURONS IN THE MOUSE-BRAIN, Psychopharmacology, 118(3), 1995, pp. 267-272
The present experiments investigated the effects of a novel stress cha
llenge (6-min swim test) on behaviour (immobility) and the neurochemis
try of cortical 5-hydroxytryptaminergic neurones in CD1 mice. The infl
uence of previous experience of stress (once-daily saline injection) o
r administration of the noradrenaline and 5-hydroxytryptamine (5-HT) u
ptake blocker, sibutramine hydrochloride, on any changes was also eval
uated. 5-HT2A receptor binding was unchanged 24 h after the last injec
tion of either saline or sibutramine alone but immobility in the swim
test was reduced to the same extent by these pretreatments. Seven days
, but not 3 h, after the swim test, the density of 5-HT2A receptors an
d the frequency of 5-HT2A receptor-mediated head-twitches were increas
ed significantly. These increases were prevented by saline injection,
but sibutramine prevented the increase in head-twitches only. Sibutram
ine, but not saline, reduced 5-HT synthesis and 5-HT2A receptor-mediat
ed head-twitches 3 h after the swim and increased synthesis at 7 days.
The results indicate that a brief stress can have long-term effects o
n central 5-hydroxytryptaminergic neurones. Previous experience of str
ess or sibutramine has marked, but dissimilar, effects on these change
s. These findings might be relevant to long-lasting CNS disorders prov
oked, or aggravated, by stress.