Effects of altered brain noradrenaline level on acute stress pathology in rats.

Abstract

The present study sought to examine pre-stress manipulations designed to alter brain NA levels in animals prior to their being exposed to the acute stressor of supine restraint-cold. Forty rats were divided into five equal groups which were given either no pre-treatment (control) ; a brief swim; a 1 hr. period of random, inescapable footshock; a 1 hr, period of footshock pre-ceded by desipramne HCl administration; or a single injection of methampheta -mine HCl. Following 3 hrs. of supine restraint-cold, all rats were decapitated and their brains removed and analyzed fluorometrically for NA, DA and MHPG -SO4. Stomach, thymus, spleen and adrenals were also dissected and examined. Trunk blood was also assayed for plasma corticosterone. Results showed that cold swim pre-treatment produced significantly decreased NA level and signifi-cantly elevated MHPG-SO4 level, indicative of greater NA turnover. These animals also displayed the greatest extent of gastric damage. Desipramine at-tenuated the effects of inescapable shock exposure and along with the metham-phetamine -treated animals, displayed less gastrointestinal ulcers. A modest relationship was observed between NA level and ulcer frequency. It is suggested that brain NA level prior to exposure to an acutely stressful situation is an important determinant of the severity of the pathophysiological response of an organism to that situation.