Neuropeptide Y in brains of the Flinders Sensitive Line rat, a model of depression. Effects of electroconvulsive stimuli and d-amphetamine on peptideconcentrations and locomotion

Neuropeptide Y (NPY), has been implicated in the pathophysiology of depress ion and the mechanisms of action of electroconvulsive treatment (ECT). In t his series of experiments, we explored whether there are differences betwee n Flinders Sensitive Line (FSL) rats, an animal model of depression, and co ntrols, Flinders Resistant Line (FRL) in (1) baseline brain NPY-LI concentr ations, (2) effects of ECS on locomotion and brain neuropeptides, (3) amphe tamine effects on behavior, and (4) effects of ECS pretreatment on subseque nt effects of amphetamine on behavior. Both strains were divided into two g roups, receiving eight ECS or ShamECS. Twenty-four hours after the last ses sion, animals were habituated in activity boxes for 45 min before given d-a mphetamine (1.5 mg kg(-1), subcutaneously) or vehicle. Locomotor activity w as then recorded for an additional 45 min. Twenty-four hours later, rats we re sacrificed by microwave irradiation, the brains dissected into frontal c ortex, occipital cortex, hippocampus, hypothalamus and striatum, and the ne uropeptides extracted and measured by radioimmunoassay. No differences betw een FSL and FRL rats in baseline locomotor activity were found. FSL compare d to FRL animals showed a significantly larger locomotion increase followin g saline and a significantly smaller increase following amphetamine. ECS pr etreatment significantly decreased the saline effects on locomotion in the FSL and the amphetamine effects in the FRL rats. 'Baseline' NPY-like immuno reactivity (LI) concentrations were lower in the hippocampus of the 'depres sed' rats. ECS increased NPY-LI in frontal cortex, occipital cortex and hip pocampus of both strains. The hippocampal NPY-LI increase was significantly larger in the FSL compared to FRL animals. (C) 2000 Elsevier Science B.V. All rights reserved.