Changes of Tissue Blood Flow in Mice Loaded with SART (Repeated Cold) Stress or Restraint and Water Immersion Stress and the Effect of Administered Neurotropin

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Abstract
In order to explore the peripheral microcirculation and to obtain an outline of autonomic innervation in SART (specific alternation of rhythm in temperature)-stressed (repeated cold-stressed) animals, which are regarded as model animals for clinical vagotonic-type dysautonomia, peripheral tissue blood flow was determined in mice, using the hydrogen clearance method. SART-stressed mice showed a decrease in gastric blood flow, no change in hepatic blood flow and an increase in dermal blood flow. In the mice exposed to the restraint and water immersion stress (RWIS), a type of acute stress, in contrast with SART stress which is a subacute type, remarkable decreases were observed in gastric, hepatic and dermal blood flows. Changes of both gastric and dermal blood flow in SART-stressed mice were dose-dependently prevented and maintained within normal limits by the treatment with Neurotropin, a sedative analgestic which is an extract isolated from vaccinia virus-inoculated and inflamed skin of rabbits. In RWIS-loaded mice, Neutropin exhibited a great preventive effect on changes of blood flow in the stomach, a slight effect in the liver and no effect in the cutis. When mice were loaded with SART stress after left-cervical vagotomy, SART stress failed to elicit any decrease in gastric blood flow. In SART-stressed mice treated with 6-hydroxydopamine, gastric and dermal blood flows tended to show a further decrease and increase, respectively, over and above the changes caused by SART stress. From these results, it is suggested that SART-stressed mice may have decreased gastric parasympathetic tone, a decrease in sympathetic tone and also other anomalies such as increased tension of the sympathetic cholinergic vasodilator nerves in the cutis.
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