Effects of α- and β-adrenergic receptor antagonists on retrograde amnesia produced by frontal cortex stimulation

This study assessed the effects of adrenergic antagonists on the development of retrograde amnesia. Animals were trained on either a one-trial inhibitory (passive) avoidance task or a visual discriminated avoidance Y-maze. Thirty minutes prior to training animals received an injection of the β-adrenergic antagonists propranolol (0.5 mg/kg), saline, or one of the following α-adrenergic antagonists: phentolamine (10 mg/kg), piperoxane (5 mg/kg), or phenoxybenzamine (2 mg/kg). Shortly after training, the animals received frontal cortex stimulation (5 mA/1 sec) through implanted cortical screw electrodes. The results indicate that pretreatment of rats with any of these α- and β-adrenergic antagonists attenuates the production of retrograde amnesia. These findings add further support to the view that an adrenergic response to amnestic treatments may be a component of a restricted set of biological systems that are involved in retrograde amnesia.