Neuropeptide Y in male and female brains of flinders sensitive line, a ratmodel of depression. Effects of electroconvulsive stimuli

Human and animal studies suggest that neuropeptide Y (NPY), a peptide co-lo calized and co-released with classical neurotransmitters, is involved in th e pathogenesis of affective disorders. In addition, lithium, electroconvuls ive treatments (ECT in humans and ECS in rodents) and antidepressants affec t NPY in a specific temporal- and brain-region fashion. These results have been obtained on healthy male rats; females and/or "depressed" animals have essentially not been studied. Consequently, we studied brain NPY-like immu noreactivity (-LI) under basal conditions and following a series of ECS in both male and female Flinders Sensitive Line (FSL), an animal model of depr ession, and their controls, the Flinders Resistant Line (FRL) rats. Further more, we examined whether the oestrus cycle affects NPY-LI in these strains . Following sacrifice by focused microwave irradiation, the peptides were e xtracted From dissected brain regions and measured by radioimmunoassay. Hip pocampal NPY-LI in both sexes was significantly lower in the "depressed" FS L compared to the control FRL. ECS increased NPY-LI in both male and female rats in both FSL and FRL strains in hippocampus, frontal cortex and occipi tal cortex. In the hypothalamus, the increase was found only in the FSL rat s. In both FSL and control rats. the basal NPY-LI was lower in the hippocam pus of female compared to male rats. NPY-LI did not vary during the differe nt phases of the oestrus cycle. These results suggest that the gender diffe rences are not due to NPY-LI variations during the oestrus. The results are consistent with our hypothesis that NPY plays a role in the pathophysiolog y of depressive disorders and provide further evidence that one of the mode s of ECS action is to elevate NPY in the limbic system. Assumption that gen der differences in NPY could explain increased rates of depression in women is speculative, but is in line with the findings in the present study. (C) 2001 Elsevier Science Ltd. All rights reserved.