Estrogen and estrogen-progesterone treatments counteract the effect of scopolamine on reinforced T-maze alternation in female rats.

Determined if steroid hormone treatments would attenuate the effect of the muscarinic receptor blocker scopolamine on a memory task. Ovariectomized rats were trained first to alternate for food reward between the arms of a T maze. Following training, Ss treated with scopolamine hydrobromide (0.2 mg/kg, ip) did not alternate correctly between the arms of the T maze and responded at chance levels. However, when estradiol benzoate (25 μg) was administered 72, 48, and 24 hrs before testing alone or in combination with progesterone (500 μg) administered 48 hrs before testing, Ss alternated successfully between the arms of the T maze following scopolamine administration. Results indicate that gonadal steroids can completely counteract the impairment of T maze performance induced by scopolamine in female rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)