Intracerebroventricular Administration of Mineralocorticoid Receptor Antisense Oligonucleotides Attenuates Salt Appetite in the Rat

The anterior ventral third ventricle (AV3V) region of the brain contains high concentrations of mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) that are important in the maintenance of body fluid and electrolyte balance as well as other physiological processes. Daily intracerebroventricular pulse injections of MR antisense oligonucleotides significantly suppressed deoxycorticosterone acetate (DOCA) induced salt appetite in a dose-related manner. Similar administration of GR antisense or scrambled/sense oligonucleotide into the third ventricle failed to inhibit salt appetite. Salt appetite aroused after adrenalectomy was not suppressed by MR antisense oligonucleotide treatments but was suppressed by an antisense oligonucleotide directed against the angiotensin II AT1 receptor subtype. Receptor binding analysis demonstrated that MR and GR oligonucleotide treatments each reduced their respective receptor subtypes. Finally, although GR antisense oligonucleotide treatment was ineffective in suppressing DOCA-induced salt appetite, this treatment did increase stress induced corticosterone release as well as delayed the recovery of corticosterone to basal levels after stress.     

Covert behavior as a direct electromyographic measure of mediating responses

Electromyographic (EMG) measures (in addition to eye activity, and electroencephalograms, EEG) were taken from the tongue and arms of children under conditions of verbal oral mediation, non-oral (leg and arm) mediation based on the concepts of right and left, and no-mediation. It was found that amplitude of tongue EMG (a measure of covert oral behavior) significantly increased only for the Verbal Mediation Group, and the increase was significantly greater than for the other two (control) groups. The arms were possible loci of mediational behavior for the Non-oral Mediation Group; arm EMG was relatively large under this non-oral mediation condition, the changes being significant for the left arm. Eye movements, possible indicators of right and left mediational activity, were greater under the non-oral mediation condition, too. These psychophysiological measures of covert behavior during mediation are thus consistent with verbal mediational theory that has been based on the study of overt behavior.