PRODUCTION OF THE ALARM REACTION IN YOUNG RATS BY TRANSECTION OF THE SPINAL CORD

Abstract

Immature rats killed 48 hrs. after transection of the spinal cord just below the vertebra prominens showed decrease in avg. thymus wt. of about 1, and increase in avg. adrenal wt. of about 2/5, as compared with unoperated controls. The extent of these changes was unaffected by the prevention of the fall in body temp. which usually follows cord section. Simple laminectomy without cord section produced qualitatively similar but much less extensive changes. Thymus wts. showed a somewhat irregular and inconclusive tendency to return to normal 10-12 days after transection of the spinal cord. A 2d transection of the cord, 10-12 days after the first, and caudal to it, might be capable of producing a 2d involution of the thymus. The effect on adrenal wt. was inconstant. In none of the series of operated rats were significant rank order correlations obtained between involution of the thymus and enlargement of the adrenals. Histologically the thymi of operated rats tended to be depleted of lymphocytes. No constant histological changes were observed in the adrenals. Stomach hemorrhages were seen almost invariably in animals which had been per mitted to become chilled following transection of the cord, but never in those whose body temp. had been maintained. Bladder hemorrhages were found inconstantly 48 hrs. after a single spinal cord transection, but under no other circumstances.