Effects of reserpine on blood-pressure responses evoked from the hypothalamus.

Different areas of the hypothalamus were stimulated by a stereotaxic technique before and after reserpine in unanaesthetized cats. Reserpine in a dose of 1 mg./kg. body weight increased the threshold of stimulation of hypothalamic areas in cats giving an initial pressor response. It decreased the threshold of stimulation of areas of the hypothalamus in animals giving an initial depressor response. Reserpine thus appeared to affect the hypothalamus directly in two ways. It depressed the sympathetic centres in the diencephalon and facilitated the parasympathetic ones.