5-Hydroxytryptamine 1A Receptor Activation Protects againstN-Methyl-d-aspartate-Induced Apoptotic Cell Death in Striatal and Mesencephalic Cultures

Abstract

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 ϩ )-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(WAY 100635) and S-UH-301, respectively. Similarly, doseand 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 Ca 2ϩ 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 ϩ . Together, these results suggest that 5-HT1A receptor stimulation may be a promising pharmacological approach in the development of neuroprotective agents for PD.Parkinson's disease (PD) is a major neurodegenerative disorder with a lifetime incidence of 1 to 2%. The drug L-DOPA has been the gold standard PD treatment for more than three decades now and can bring considerable relief from the debilitating symptoms of the disease. However, its long-term use has several limitations, including severe fluctuations in effectiveness and drug-induced involuntary movements (Fahn, 1999;Carlsson, 2002). Importantly, L-DOPA simply compensates for the dopamine deficiency in Parkinson's patients and fails to attenuate the progression of the disease. Hence, novel neuroprotective agents designed to interfere with the basic pathogenic mechanism of cell death in PD are clearly needed.Excitotoxic mechanisms may contribute to the nigrostriatal degeneration in PD (Greenamyre, 1993;Olanow and Tatton, 1999). Glutamate binds to a variety of excitatory amino acid receptors, especially the NMDA receptor, leading to prolonged and excessive depolarization and neuronal activation resulting in the death of target neurons (Choi, 1988;

Ester Derivatives of Tournefolic Acid B Attenuate N-Methyl-d-aspartate-Mediated Excitotoxicity in Rat Cortical Neurons

“…However, the underlying mechanisms remain unclear. Studies have shown that glutamate activates caspase 3 in cultured cortical neurons, striatal neurons, and mesencephalic neurons (Liu and Zhu, 1999;Madhavan et al, 2003). Our previous study also demonstrates that glutamate ubiquitously elicits the activation of caspases 2, 3, 6, 8, and 9 (Chi et al, 2005).…”

Neuroprotective effect of ziprasidone: Preliminary results compared to haloperidol

“…5-HT1A receptor stimulation rescued cultured hippocampal neurons from glutamate-mediated excitotoxicity and protected against ischemic neuronal cell death (Nakata et al, 1997;Harkany et al, 2001;Madhavan et al, 2003). Previous studies have shown that 5-HT1A receptor stimulation can (Strosznajder et al, 1996;Matsuyama et al, 1997;Madhavan et al, 2003). Other mechanisms, in addition to inhibition of N-methyl-D-aspartate (NMDA)-induced Ca 2+ influx, may be important in the neuroprotection resulting from 5-HT1A receptor stimulation.…”

“…Other mechanisms, in addition to inhibition of N-methyl-D-aspartate (NMDA)-induced Ca 2+ influx, may be important in the neuroprotection resulting from 5-HT1A receptor stimulation. Madhavan et al suggested that 5-HT1A receptor stimulation protects against NMDA-mediated apoptotic cell death in both striatal and nigral neurons (Madhavan et al, 2003). Prehn et al (1993) suggest that 5-HT, released during ischemia, may have protective effects in the pathophysiology of ischemic brain damage through a direct action on neurons mediated via the inhibitory 5-HT1A receptor subtype.…”

“…Stimulation of the 5-HT1A receptor may play a role in neuronal survival (Raymond et al, 2001;Madhavan et al, 2003). 5-HT1A receptor stimulation rescued cultured hippocampal neurons from glutamate-mediated excitotoxicity and protected against ischemic neuronal cell death (Nakata et al, 1997;Harkany et al, 2001;Madhavan et al, 2003).…”

Dynamics of neural stem cell-mediated neuroprotection in the presence of oxidative stress: studies in vitro and in vivo

“…Apoptotic cells in vitro were detected in a standard nuclear stain with the Hoechst dye 33342 and cells with apoptotic (condensed and/or fragmented) nuclei were quantified as described (Madhavan et al, 2003). Pure growth factor proteins provided in the kit were used to establish standard curves for quantification.…”