Expression of the c-fos gene in spinal cord and brain cells in rats subjected to stress in conditions of exposure to various types of halothane anesthesia.

The influences of different treatments on the expression of the c-fos gene in the spinal cord and brain (hypothalamus) was studied in rats using various types of anesthesia. Synthesis of c-Fos-like proteins occurred only in the spinal cord in conditions of constant 1.5% halothane anesthesia. Use of induction anesthesia with 1.5% halothane allowed detection of c-Fos-like protein expression in cells of the rat spinal cord (lumbar segments) and brain, both when animals were placed in a hammock and when mechanical pain stimulation or electromagnetic irradiation of the skin with UHF currents were applied. The pattern of brain structures reacting to mechanical pain stimulation with expression of c-Fos-like protein was identified. This type of stimulation was shown to induce increases in the quantity of c-Fos-positive cells in the lateral hypothalamic area (LHA), the ventromedial (VMH) and dorsomedial (DMH) hypothalamic nuclei, and in the ventral hypothalamic area (AHA) by 116%, 167%, 101%, and 157% respectively as compared with controls. Skin irradiation with UHF currents decreased the intensity of mechanical pain stimulation-induced synthesis of c-Fos-like protein in most structures (LHA, VMH, DMN, and AHA by 32.8%, 29%, 15%, and 33% respectively). Only induction halothane anesthesia allowed identification of hypothalamic structures reacting to mechanical pain stimulation and the modifying effects of irradiating the skin with UHF currents on the intensity of these reactions.