Vol. 304, Issue 3, 913-923, March 2003

5-Hydroxytryptamine 1A Receptor Activation Protects against N-Methyl-D-aspartate-Induced Apoptotic Cell Death in Striatal and Mesencephalic Cultures

Lalitha Madhavan, William J. Freed, Vellareddy Anantharam and Anumantha G. Kanthasamy

Parkinson's Disorder Research Laboratory, Department of Biomedical Sciences, Iowa State University, Ames, Iowa (L.M., V.A., A.G.K.); and Cellular Neurobiology Branch, National Institute on Drug Abuse, Baltimore, Maryland (W.J.F.)

Apoptosis and glutamate-mediated excitotoxicity may play a role in the pathogenesis of many neurodegenerative disorders, including Parkinson's disease (PD). In the present study, we investigated whether stimulation of the 5-hydroxytryptamine 1A (5-HT1A) receptor attenuates N-methyl-D-aspartate- (NMDA) and 1-methyl-4-phenylpyridinium (MPP⁺)-induced apoptotic cell death in cell culture models. A brief exposure (20 min) of M213-2O striatal cells to NMDA and glutamate produced a delayed increase in caspase-3 activity and DNA fragmentation in a dose- and time-dependent manner. NMDA-induced caspase-3 activity and DNA fragmentation were almost completely blocked by the 5-HT1A agonists 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) and (R)-5-fluoro-8 hydroxy-2-(dipropylamino)-tetralin (R-UH-301). Additionally, the protective effects of 8-OH-DPAT and R-UH-301 on NMDA-induced caspase-3 activation and apoptosis were reversed by pretreatment with the 5-HT1A antagonists N-[2-[4-(2-methoxyphenyl)-1-piperazinyl] ethyl]-N-(2-pyridinyl) cyclohexane carboxamide (WAY 100635) and S-UH-301, respectively. Similarly, dose- and time-dependent increases in caspase-3 activity and DNA fragmentation were observed in rat primary mesencephalic neurons after a brief exposure to NMDA and glutamate. Caspase-3 activation and DNA fragmentation in primary mesencephalic neurons were almost completely inhibited by 8-OH-DPAT. This neuroprotective effect of 8-OH-DPAT was reversed by WAY 100635. Additionally, 8-OH-DPAT blocked tyrosine hydroxylase (TH)-positive cell death after NMDA exposure and also almost completely attenuated the NMDA-induced Ca²⁺ influx in primary mesencephalic cultures. Furthermore, 8-OH-DPAT and R-UH-301 blocked apoptotic cell death in the primary mesencephalic neurons that were exposed to the Parkinsonian toxin MPP⁺. Together, these results suggest that 5-HT1A receptor stimulation may be a promising pharmacological approach in the development of neuroprotective agents for PD.