Modulation of neurogenesis and selected neuropeptides expression in the hypothalamus of rats exposed to neuroleptic
Patients treated with neuroleptics suffer from significant weight gain. Hypothalamus consists of neuronal circuits responsible for food intake regulation. Moreover, last finding suggest that adult neurogenesis occurs in the hypothalamus, which could play a role in the energy expenditure control. Considering that neuroleptics affect neural formation in the canonical neurogenic sites, we made a hypothesis that they could modulate hypothalamic neurogenesis and change expression of orexigenic/anorexigenic neuropeptides and their receptors. Experiments were carried out on adult male rats injected intraperitoneally for 1 or 28 days by the neuroleptics: olanzapine, chlorpromazine and haloperidol. Hypothalami were isolated in order to perform RT-PCR reaction and also whole brains were sliced for immunohistochemical assay. We observed that antipsychotics administered chronically supported the origin of newborn cells (Ki67 +) in the hypothalamic regions and affect the number of DCX-positive immature neurons. Furthermore, they have a distinct ability to upregulate preproorexin and orexin A expression and to increase the level of some anorexigenic factors (POMC, α-MSH), at the same time strongly decreasing nesfatin-1 signalling. Our results highlight the role of neuroleptics as potential modulators of the hypothalamic neurogenesis and contribute to better understanding the mechanisms of their side effects. They also underline the complexity of interplay between monoamine receptors, hypothalamic peptidergic pathways and adult neurogenesis which has putative but possible pharmacological applications.