Progesterone Attenuates Several Hippocampal Abnormalities of the Wobbler Mouse

It is now recognised that progesterone plays a protective role for diseases of the central nervous system. In the Wobbler mouse, a model of motoneurone degeneration, progesterone treatment prevents spinal cord neuropathology and clinical progression of the disease. However, neuropathological and functional abnormalities have also been discovered in the brain of Wobbler mice and patients with amyotrophic lateral sclerosis. The present study examined the hippocampus of control and afflicted Wobbler mice and the changes in response to progesterone treatment. Mice received either a single progesterone implant (20 mg for 18 days). We found that the hippocampal pathology of the untreated Wobblers involved a decreased expression of brain-derived neurotrophic factor (BDNF) mRNA, decreased astrogliosis in the stratum lucidum, stratum radiatum and stratum lacunosum-moleculare, decreased doublecortin (DCX)-positive neuroblasts in the subgranular zone of the dentate gyrus and a decreased density of GABA immunoreactive hippocampal interneurones and granule cells of the dentate gyrus. Although progesterone did not change the normal parameters of control mice, it attenuated several hippocampal abnormalities in Wobblers. Thus, progesterone increased hippocampal BDNF mRNA expression, decreased glial fibrillary acidic protein-positive astrocytes and increased the number of GABAergic interneurones and granule cells. The number of DCX expressing neuroblasts and immature neurones remained impaired in both progesterone-treated and untreated Wobblers. In conclusion, progesterone treatment exerted beneficial effects on some aspects of hippocampal neuropathology, suggesting its neuroprotective role in the brain, in agreement with previous data obtained in the spinal cord of Wobbler mice.