Modulation of spiking of neurons of the cat anterior hypothalamus induced by experimental shifts in the osmolarity of the blood plasma

• Published in: Neurophysiology (New York) 2006-01, Vol.38 (1), p.34-38
• Main Author: Natrus, L. V.
• Format: Article
• Language: English
• Subjects: Brain; Cats; Neurons; Osmosis; Plasma; Salt; Water
• ISSN: 0090-2977; 1573-9007
• DOI: 10.1007/s11062-006-0023-0

We examined changes in the impulse activity (IA) generated by neurons of the anterior hypothalamus (including the preoptic region) resulting from infusions of hyper-and hypotonic NaCl solutions (3.0 and 0.2%, respectively; hyper-and hypoosmotic stimulations, respectively); the infused volumes did not exceed 200 microl. The effects of hyper-and hypoosmotic stimulations were studied in detail in 83 and 88 neurons, respectively. In 31.2% (26 cells) and 29.6% (26 cells) of the neurons of the above groups, these stimulations evoked changes in the IA frequency greater than +40 or -40% of the mean background IA frequency. In approximately 50% of the responding neurons in each group, such shifts in the IA frequency were observed in the course of infusions of test solutions (5 sec long) and within the subsequent 5 min after termination of the infusion. In another 50% of the neurons, changes in the IA frequency occurred within the afterperiod (30 sec long); these shifts could develop exclusively within the latter interval, or these changes accompanied an initial early reaction. In general, activating responses dominated (they were observed in 65% of the cases where test stimulations of both modalities were used). The possible aspects of the involvement of neurons of the anterior hypothalamus in the control of the water/salt balance in the organism are discussed. [PUBLICATION ABSTRACT]