Aims: Many patients taking risperidone for the treatment of psychiatric disorders experience substantial body weight gain. Researchers have speculated that risperidone induces obesity by modulating central signals; however, the precise central mechanisms involved remain to be fully elucidated.Methods: Twenty-four C57BL/6J mice were divided into four groups: a control group; a risperidone-treated group; a lorcaserin-treated group; and a combined risperidone + lorcaserin-treated group. The mice were received the corresponding treatments for 4 weeks, and their brains were collected for in situ hybridization analysis. A subset of C57BL/6J mice was administrated with risperidone or placebo, and brains were collected 60 minutes post-treatment for determination of c-fos activity. In addition, brains of NPY-GFP mice treated with or without risperidone were collected to perform colocalization of NPY and c-fos, as well as NPY and 5-HT2c receptor using immunohistochemistry.
Results:There was significantly elevated c-fos expression in the hypothalamic arcuate nucleus (Arc) of risperidone-treated mice. More than 68% c-fos-positive neurons were NPY-expressing neurons. Furthermore, in situ hybridization revealed that Arc NPY mRNA expression was significantly increased in the risperidone-treated group compared with control group. Moreover, we identified that 95% 5-HT2c receptors were colocalized with NPY positive neurons, and increased Arc NPY mRNA expression induced by risperidone was markedly reduced by cotreatment with lorcaserin, a specific 5-HT2c receptor agonist.
Conclusion:Our findings provide critical insight into the mechanisms underlying antipsychotic-induced obesity, which may assist the development of therapeutic strategies to address metabolic side effects of risperidone.
K E Y W O R D S5-HT2c receptor, hypothalamic arcuate nucleus (Arc), NPY, obesity, risperidone
Summary
Inverted feeding is a paradigm to study synchronization of circadian clocks by feeding rhythm in tissues more directly. Here, we provide a protocol for performing inverted feeding in mice and analyzing circadian rhythmicity in mouse tissues. We describe setting up inverted feeding and performing tissue dissection, followed by RNA extraction and gene expression analysis, and lastly R software-based analysis of circadian rhythmicity. This protocol can be combined with the use of CircaMetDB database for mechanistic studies of inverted feeding.
For complete details on the use and execution of this protocol, please refer to
Xin et al. (2021)
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