PATTERNS OF C-FOS EXPRESSION INDUCED BY FLUVOXAMINE ARE DIFFERENT AFTER ACUTE VS. CHRONIC ORAL-ADMINISTRATION

Fluvoxamine is a selective serotonin (5-HT) reuptake inhibitor (SSRI) with a broad spectrum of behavioral and therapeutic effects, e.g. in d epressive illness. We used the expression of c-fos, after both acute a nd chronic oral administration of fluvoxamine in the rat, to study its immediate and long-term effects, in relation to the distribution of G alanin (GAL) and Vasoactive Intestinal Polypeptide (VIP). After acute oral administration, most consistent increases were apparent in (parts of); the nucleus of the solitary tract, medial part; the lateral para brachial nucleus, external part; the bed nucleus of the stria terminal is, dorsolateral part; and the central nucleus of the amygdala, latera l part. After chronic administration, distribution of Fos-IR was simil ar to acute administration, although numbers of Fos-IR neurons were no longer significantly different from control values. It is concluded t hat activation of 5-HT3-receptors in the caudal brainstem or gastro-in testinal afferents of the vagal nerve may Flay a role in the observed pattern of Fos-IR after fluvoxamine administration. The relationship w ith the antidepressant effects of fluvoxamine needs further investigat ions. (C) 1998 Elsevier Science B.V./ECNP.