Imidazoline receptor proteins in brains of patients with Alzheimer's disease

Experiments have been carried out to investigate the chemical substrate in the rostral ventrolateral medulla (RVLM) underlying the depressor responses induced by activation of the greater splanchnic nerve (GSPL) afferent fibres of the rat. In anaesthetised rats with urethane and alpha-chloralose, microinjection of bicuculline, a GABA(A) receptor antagonist, into the RVLM, attenuated largely the depressor responses elicited by electrical stimulation of the GSPL afferent fibres, while strychnine or saline had no effect. In 18 RVLM neurons (including seven identified cardiovascular neurons), iontophoresis of bicuculline also significantly blocked the inhibition evoked by stimulation of the GSPL afferent inputs. We suggest that the depressor responses induced by stimulation of the GSPL afferent fibres involve a GABA(A)-receptor-mediated mechanism in the RVLM in rats.