Immunohistochemical study on distribution of cannabinoid cb1 receptors in the rat`s prefrontal cortex after cold stress procedure

Abstract

The prefrontal cortex (PFC), which mediates the emotional coping response to different stressful paradigms, is composed of distinct parts depends on stimulus involved physical or psychological stress. It also plays a role in a number of neurological conditions. It`s known that neuroendocrine control of homeostatic and reproductive functions including stress response and energy metabolism is fulfils by important signaling molecules as endogenous cannabinoids. The aim of the present study was to examine the effects of cold stress on distribution of CB1- receptors in PFC of rats. Immunohistochemical procedure for CB1-receptors was performed in adult male Wistar rats. The data were entered in the computer program, recorded automatically, calculated and compared by Student`s t-test. We found CB1-immunoreaction in axons and dendrites as well as in cell bodies where they presented as puncta on somata. The cells bodies were comprised of several distinct shapes: pyramidal, oval, fusiform and multipolar. Numerous fine-beaded fibers and puncta were seen on a handful of pyramidal large-sized neurons and many puncta were observed around the oval-shaped small- and medium-sized neurons.The PFC in cold stress rats demonstrated around 18% higher density of CB1-receptors compared with controls. In conclusion our results showed that cold stress exposure increased distribution of CB1-receptors in PFC of rats. These experimental data suggest that endocannabinoid system in this brain area may play an important role in the continuity of homeostasis in cold stress.