BRAIN GALANIN RECEPTORS AND EPILEPSY

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DESCRIPTION (provided by applicant): The long-term objective of this project is to understand the mechanisms involved in inhibition of seizure activity by the neuropeptide galanin. Our lab was the first to show that seizures alter galanin in the hippocampus and that galanin has a profound seizure-protective effect in status epilepticus. The project has three goals. First, we will develop a novel approach to down-regulate galanin receptors in naive animals, in order to study the role of galanin receptors in seizures. This will be achieved by developing and optimizing peptide nucleic acid (PNA) antisense targeted against galanin receptor subtypes 1 and 2. The effects of PNA on galanin receptors will be examined by studying galanin receptor binding, immunocytochemistry, and Western blot in galanin receptor-transfected cell lines and primary neuronal cultures. Second we will test the hypothesis that down-regulation of galanin receptor subtypes in the brain selectively increases animals' predisposition to seizures, and increases seizure-related neuronal injury. We will examine the differences between naive and galanin receptor PNA-treated rats in the initiation and maintenance of seizure activity during self-sustaining status epilepticus, and will compare the degree of neuronal injury between control and PNA-treated rats. Third, we will study putative mechanisms that underlie seizure-protective effects of galanin receptor stimulation. Specifically, we will study how galanin receptor PNA treatment affects second messenger systems (cyclic adenosine monophosphate, phosphoinisitide turnover, mitogen-activated protein kinase activity, excitatory amino acid glutamate release) and will correlate these effects with the effects of PNA on status epilepicus. The proposed project will yield important data for understanding brain mechanisms that participate in endogenous suppression of seizures, and will justify the use of active ligands of galanin receptors as a new approach for the treatment of epilepsy.