Protective effect of galanin on behavioral deficits in experimental traumatic brain injury

The magnitude of behavioral deficits in traumatic brain injury (TBI) has been shown to be partly related to alterations in the balance between excitatory and inhibitory neurotransmitter release. Previous studies have demonstrated that extracellular excitatory neurotransmitter concentrations dramatically increase following experimental TBI. We examined the effects of a neuromodulatory peptide, galanin (GAL), on behavioral morbidity, as measured by sensory motor and memory performance tasks, associated with experimental TBI in the rat. A single intraventricular injection of GAL (1.0 micrograms, n = 8 or 10.0 micrograms, n = 10) or cerebrospinal fluid (CSF) vehicle (n = 10) was administered 5 minutes prior to central fluid percussion TBI in rats. Performance on sensory motor tasks was assessed prior to injury and for 5 days after TBI with beam-balance, beam-walking, and rotarod tasks. Memory performance was assessed on days 11-15 after TBI with the Morris water maze. TBI produced significant motor and memory deficits in the CSF-treated group. GAL-treated rats had significantly less magnitude of deficits compared to CSF-treated rats on beam-balance, beam-walking, and rotarod performance. The 1.0 micrograms GAL dose produced slightly greater protection than the 10.0 micrograms GAL dose. Neither GAL dose affected body weight loss or Morris water maze performance. These results suggest that the physiologic effects of GAL may reduce certain components of TBI morbidity, possibly by modulating neuronal excitability.