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
