Apoptosis Induced by gp120 in the Neocortex of Rat Involves Enhanced Expression of Cyclooxygenase Type 2 and Is Prevented by NMDA Receptor Antagonists and by the 21-Aminosteroid U-74389G M. T. Corasaniti,* M. C. Strongoli,* S. Piccirilli,† R. Nistico `,† A. Costa,‡ A. Bilotta,* P. Turano,§ A. Finazzi-Agro `, ¶ and G. Bagetta† , § ,1 *Faculty of Pharmacy and IBAF-CNR, Catanzaro, Italy; †“Mondino-Tor Vergata” Center for Experimental Neurobiology, Department of Biology, and ¶ Department of Experimental Medicine and Biochemical Sciences, University of Rome “Tor Vergata”, Rome, Italy; ‡Fondazione Istituto Neurologico “C. Mondino”, University of Pavia, Italy; and §Department of Pharmaco-Biology, University of Calabria at Cosenza, Italy Received June 20, 2000 The effects of a single dose of the HIV-1 coat protein gp120 given into one lateral cerebral ventricle (i.c.v.) on the expression of cyclooxygenase type 2 (COX-2) and PGE 2 levels have been studied using Western blot- ting and ELISA techniques applied to brain tissue ex- tracts obtained from the neocortex of individual rats, one of the regions of the central nervous system where the viral protein causes apoptosis. The results demon- strate that COX-2 expression is almost doubled 6 h after a single dose (100 ng) of gp120 and this is paral- leled by a statistically significant elevation of PGE 2 . Enhanced COX-2 expression is implicated in the mech- anisms of apoptosis evoked by gp120 because the lat- ter is prevented by NS398 (10 mg/kg i.p.), a selective inhibitor of COX-2 activity. Protection is also afforded by NMDA receptor antagonists, such as MK801 (0.3 mg/kg i.p.) and CGP040116 (10 mg/kg i.p.), and by the free radical scavenger, U-74389G (10 mg/kg i.p.), sup- porting a glutamate-mediated, excitotoxic, mechanism of apoptotic death induced by gp120. These data to- gether with the observation that MK801 failed to pre- vent gp120-enhanced COX-2 expression indicate that products of the arachidonic cascade may be responsi- ble for elevation of synaptic glutamate leading neocor- tical cells to oxidative stress and excitotoxic apop- tosis. © 2000 Academic Press Key Words: HIV-1 gp120; apoptosis; COX-2; prosta- glandins; NMDA receptor antagonists; U-74389G. A proportion of patients suffering from AIDS devel- ops a neurological syndrome characterized by cognitive and motor deficits referred to as AIDS dementia com- plex (23). This syndrome has been correlated with the loss of cortical neurones described at postmortem in the brain of AIDS patients (13). A broad spectrum of in vitro studies has documented that the human immu- nodeficiency virus type 1 (HIV-1) coat protein gp120 causes excitotoxic, glutamate-mediated (see 11), death of several types of neuronal cells in culture leading to the suggestion that the viral protein may be the etiologic agent of the neuronal loss described above (see 18). We have previously reported the original observation that subchronic injection into one lateral cerebral ven- tricle (i.c.v.) of the HIV-1 coat protein, gp120, induces DNA fragmentation in the brain neocortex of rat sug- gesting an apoptotic type mechanism of cell death (1, 2). The latter hypothesis has been confirmed by the evidence that subchronic treatment with gp120 causes ultrastructural changes typical of early and late apop- tosis in the neocortex of rat (3). These data further implicate gp120 in the mechanisms underlying neuro- nal cell loss reported at postmortem in the brain of patients suffering from AIDS dementia complex (13). The mechanisms through which the coat protein causes apoptosis in the brain of rat is not known. Recently, we have reported immunohistochemical data demonstrating that subchronic i.c.v. treatment with gp120 enhances the expression of the inducible type of cyclooxygenase, also referred to as COX-2, in the neo- cortex of rat (5). Experimental evidence suggests that in the mammalian central nervous system (CNS) en- hanced expression of COX-2 and accumulation of prod- ucts of the arachidonic acid cascade, including trom- 1 To whom correspondence should be addressed at Department of Pharmaco-Biology, University of Calabria at Cosenza, 87036 Arca- vacata di Rende (CS), Italy. Fax: 39-984/493462. E-mail: gbagett@ tin.it. Biochemical and Biophysical Research Communications 274, 664 – 669 (2000) doi:10.1006/bbrc.2000.3160, available online at http://www.idealibrary.com on 664 0006-291X/00 $35.00 Copyright © 2000 by Academic Press All rights of reproduction in any form reserved.