1Neuronal expression of c-Fos protein in the brain after intraperitoneal injection of leptin in Wistar rats

Abstract: Leptin has been recognized to be an important neuroendocrine signal in the regulation of food intake and energy balance. We aimed to survey central neurons that might be activated after peripheral administration of leptin, by examining the distribution of neurons expressing c-Fos protein. Leptin dissolved at a dose of 500 μg/kg in physiological saline was intraperitoneally injected in Wistar rats. One and a half hours after the injection, rats were transcardially perfused with saline and fixed with fixatives. The brain was removed and sectioned at 40 μm in thickness. Every fourth section was treated with anti-c-Fos antiserum, and c-Fos protein was immunohistochemically stained using the avidin-biotin complex method. Control rats were injected with saline solution, and brain sections were processed similarly as described above. It was found that leptin injected intraperitoneally induced the neuronal expression of c-Fos protein in several nuclei throughout the brain. In the central nucleus amygdala, ventromedial nucleus of hypothalamus, periaqueductal gray matter, lateral parabrachial nucleus, and the solitary tract nucleus, numbers of neurons expressing c-Fos protein were much more in the test experiments than those in the control experiments. Intraperitoneally injected leptin was found to stimulate central neurons that may play some roles in the regulation of such as a food intake