3,4-Methylenedioxymethamphetamine increases interleukin-1b levels and activates microglia in rat brain: studies on the relationship with acute hyperthermia and 5-HT depletion Laura Orio,* Esther O’Shea,* Veronica Sanchez,* Jesus M. Pradillo,* Isabel Escobedo,* Jorge Camarero,* Maria A. Moro,* A. Richard Green and M. Isabel Colado* *Departamento de Farmacologia, Facultad de Medicina, Universidad Complutense, Madrid, Spain  Pharmacology Research Group, School of Pharmacy, De Montfort University, Leicester, UK Abstract 3,4-Methylenedioxymethamphetamine (MDMA) administra- tion to rats produces acute hyperthermia and 5-HT release. Interleukin-1b (IL-1b) is a pro-inflammatory pyrogen produced by activated microglia in the brain. We examined the effect of a neurotoxic dose of MDMA on IL-1b concentration and glial activation and their relationship with acute hyperthermia and 5-HT depletion. MDMA, given to rats housed at 22°C, increased IL-1b levels in hypothalamus and cortex from 1 to 6h and [ 3 H]-(1-(2-chlorophenyl)-N-methyl-N-(1-methylpro- pyl)3-isoquinolinecarboxamide) binding between 3 and 48 h. Increased immunoreactivity to OX-42 was also detected. Rats became hyperthermic immediately after MDMA and up to at least 12 h later. The IL-1 receptor antagonist did not modify MDMA-induced hyperthermia indicating that IL-1b release is a consequence, not the cause, of the rise in body temperature. When MDMA was given to rats housed at 4°C, hyperthermia was abolished and the IL-1b increase significantly reduced. The MDMA-induced acute 5-HT depletion was prevented by fluoxetine coadministration but the IL-1b increase and hyper- thermia were unaffected. Therefore, the rise in IL-1b is not related to the acute 5-HT release but is linked to the hyper- thermia. Contrary to IL-1b levels, microglial activation is not significantly modified when hyperthermia is prevented, sug- gesting that it might be a process not dependent on the hyperthermic response induced by MDMA. Keywords: 5-HT, hyperthermia, interleukin-1b, interleukin-1 receptor antagonist, 3,4-methylenedioxymethamphetamine, microglia. J. Neurochem. (2004) 89, 1445–1453. The recreationally used drug 3,4-methylenedioxymetham- phetamine (MDMA or ‘ecstasy’) produces, in the rat brain, a long-term loss of fine 5-HT axon terminals arising primarily from the dorsal raphe nucleus (O’Hearn et al. 1988). The degeneration has been demonstrated both histologically (O’Hearn et al. 1988; Molliver et al. 1990) and biochemi- cally and is reflected in a substantial decrease in the concentration of 5-HT and its metabolite, 5-hydroxyindole- acetic acid, and a reduction in the density of 5-HT uptake sites labelled with [ 3 H]-paroxetine (Sharkey et al. 1991; Hewitt and Green 1994; Colado et al. 1997). In addition to these long-lasting effects, MDMA produces, immediately after injection, an increase in 5-HT release and a hyperther- mic response which lasts at least 5–6 h (see Green et al. 2003). The rise in body temperature appears to be a key factor in the mechanism of MDMA-induced neurotoxicity when the drug is given as a single dose as a large number of recent studies have shown that inducing hypothermia or merely preventing the hyperthermia that follows MDMA attenuates, or even abolishes, the long-lasting neuronal damage (Broening et al. 1995; Colado et al. 1998, 1999). Interleukin-1b (IL-1b) is a pro-inflammatory cytokine that is mainly produced by activated microglia following diverse forms of neurodegeneration and CNS inflammation (Pearson et al. 1999; Touzani et al. 1999; Chauvet et al. 2001; Rothwell 2003). In addition, IL-1b is a potent pyrogen and Received November 20, 2003; revised manuscript received February 6, 2004; accepted February 6, 2004. Address correspondence and reprint requests to M. I. Colado, De- partamento de Farmacologia, Facultad de Medicina, Universidad Com- plutense, Madrid 28040, Spain. E-mail: colado@med.ucm.es Abbreviations used: GFAP, glial fibrillary acidic protein; [ 3 H]- PK11195, [ 3 H]-(1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)3-iso- quinolinecarboxamide); IL-1b, interleukin-1b; IL-1ra, interleukin-1 receptor antagonist; MDMA, 3,4-methylenedioxymethamphetamine; PBS, phosphate-buffered saline; PBZ, peripheral benzodiazepine. Journal of Neurochemistry , 2004, 89, 1445–1453 doi:10.1111/j.1471-4159.2004.02443.x Ó 2004 International Society for Neurochemistry, J. Neurochem. (2004) 89, 1445–1453 1445