Pharmacology of the Mechanism of Certain Effects of Reserpine in the Rat

Abstract

TWENTY minutes after receiving large doses of reserpine (5 mg/kg, given intraperitoneally), rats develop a myohypertonic-hypokinetic-cataleptic state, showing generalized tremor, piloerection, diarrhoea, ptosis and cutaneous hyperalgesia. In such a state rats do not move, but allow themselves to be dragged by the tail. The ptosis is reversible during the first 40 min after its appearance and then irreversible (compare refs. 1 and 2). We have found that the symptoms remain unaltered for 24 h, and then gradually subside to a practically normal state after 48 h. When the forelimbs of the animal under the influence of reserpine were placed on the edge of a table, and the rat held by the tail, it remained still in this position, unlike normal animals which would climb quickly onto the table. Rats placed on the edge of an open cage on their abdomen behave similarly; they do not climb or jump down as normal rats would do. The animals treated with reserpine find it difficult to swim in water and do so in an oblique (or sloping) position, and they cannot get themselves out of the water bath. Normal rats swim quickly in a near horizontal position and get out of the water easily.