[Characteristics of osmotic sensitivity of cells of the supraoptic nucleus of the rat hypothalamus].

The supraoptic neurons were differentiated into different types by means of antidromic stimulation of the hypothalamo-hypophyseal tract and their responses to i. v. administration of 1 M NaCl solution. I. v. administration of hypertonic NaCl solution induced the activation response in all the neurons. The neurons responding with a single spike to the tract stimulation, reacted only to administration of 1 M NaCl. The neurons responding orthodromically with a high-frequency burst as well as the neurons with no responses to the tract stimulation, revealed reactions of activation similar in time characteristics in administration of both the physiological and the hypertonic solutions. Besides, these neurons were responsive to stimulation of the ipsilateral femoral nerve as well. Possible role of these types of neurons in the functional organization of the rat hypothalamus' supraoptic nucleus, is discussed.