EN
There is a large body of research indicating that occurrence of hippocampal (HPC) theta dependent on the integrity of ascending pathway originating in the brainstem reticular formation. Anatomical studies indicate that reticular influences are relayed via the posterior hypothalamus, specifically the posterior hypothalamic (PH) and supramammillary (SuM) nuclei. In addition, neurons localized in these nuclei discharge rhythmically and in phase with HPC theta. Recently we have shown that local theta activity could be generated in anesthetized rats in PH and SuM nuclei. Recorded signal was produced independently of simultaneously occurring HPC theta and had a cholinergic profile. In the preset study we extended pharmacological observation; specifically, carbenoxolone (CBX – 75 μg/ μl; gap junction (GJ) blocker and mineralocorticoid receptor agonists) was administrated into posterior hypothalamus in urethanized rats. Injection of CBX, induced well synchronized theta activity. The effect of CBX was not antagonized by injection of GJ opener – trimethylamine (45 μg/μl) – but was abolished by antagonist of mineralocorticoid receptor, spironolactone (10 μg/1 μl). These results demonstrate for the first time that PH theta is mediated not by GJ but by mineralocorticoid receptors. Studies supported by NCN grant no. 2011/01/B/NZ4/00373.