Fluvoxamineis is an antidepressant which pharmacologically functions as a selective serotonin reuptake inhibitor. Serotonin, also known as 5-HT, is amonoamine neurotransmitter with various physiological functions such as mood, appetite, and sleep[1].

In vitro: Fluvoxamine effectively inhibited 5-HT uptake by blood platelets and brain synaptosomes [1].Fluvoxamine (10 mg/kg) increased [5-HT]ex levels in all brain areas and increased [DA]ex levels in the striatum. Fluvoxamine (10 mg/kg) in combination with of quetiapine (10 mg/kg) increased [DA]ex and [5-HT]ex levels in all brain areas when compared with baseline. The combination produced a significant increase of [DA]ex levels in the prefrontal cortex and thalamus whereas neither quetiapine nor fluvoxamine in monotherapy affected [DA]ex levels [2]. Fluvoxamine induced antiallodynic effects on neuropathic pain via descending 5-HT fibers and spinal 5-HT2A or 5-HT2C receptors, and the antinociception on acute mechanical pain via 5-HT3 receptors [3].

In vivo: Single administration of fluvoxamine (10 and 30 mg/kg, i.p.) dose-dependently enhanced synaptic efficacy in the hippocampo-mPFC pathway [4]. Fluvoxamine (10 and 30 mg/kg, i.p.) treatment suppressed long-term potentiation (LTP) in the hippocampal CA1 field of anesthetized rats. NAN-190 (0.5 mg/kg, i.p), the 5-HT(1A) receptor antagonist, completely reversed the fluvoxamine (30 mg/kg, i.p.) suppression of LTP [5].

References:
[1]. Claassen V,Davies JE,Hertting G,Placheta P. Fluvoxamine, a specific 5-hydroxytryptamine uptake inhibitor.Br J Pharmacol.1977 Aug;60(4):505-16.
[2]. Denys D1,Klompmakers AA,Westenberg HG. Synergistic dopamine increase in the rat prefrontal cortex with the combination of quetiapine and fluvoxamine.Psychopharmacology (Berl).2004 Nov;176(2):195-203. Epub 2004 May 11.
[3]. Honda M1,Uchida K,Tanabe M,Ono H. Fluvoxamine, a selectiveserotoninreuptake inhibitor, exerts its antiallodynic effects on neuropathic pain in mice via 5-HT2A/2C receptors.Neuropharmacology.2006 Sep;51(4):866-72. Epub 2006 Jul 17.
[4]. Ohashi S1,Matsumoto M,Otani H,Mori K,Togashi H,Ueno K,Kaku A,Yoshioka M. Changes in synaptic plasticity in the rat hippocampo-medial prefrontal cortex pathway induced by repeated treatments with fluvoxamine.Brain Res.2002 Sep 13;949(1-2):131-8.
[5]. Kojima T1,Matsumoto M,Togashi H,Tachibana K,Kemmotsu O,Yoshioka M. Fluvoxamine suppresses the long-term potentiation in the hippocampal CA1 field of anesthetized rats: an effect mediated via 5-HT1A receptors.Brain Res.2003 Jan 3;959(1):165-8.