Neurochemical studies on bifemelane, a new cerebral function improver: I. Effects of bifemelane on the function of neurotransmission-related enzymes and receptors in rat brain

We examined neurochemically the effects of bifemelane (BF) on muscarinic ACh (mACh-R) and /3-adrenergic receptors (β-AdR) and imipramine binding sites and the activities of acetylcholinesterase (AChE), choline acetyltransferase (CAT) and monoamine oxidase (MAO) in the P2 fractions of rat brain, ex vivo and in vitro. Male rats were given daily injections of 10, 30 mg/kg BF, p.o., for a period of 4 weeks. The Kd and Bmax values for mACh-R in the rat forebrain by administration of 10, 30 mg/kg BF decreased significantly compared with that of the control, although the Kd and Bmax values for β-AdR and imipramine binding sites were almost identical. The Km and Vmax values of A and B-form MAO decreased in rats that had been administered 30 mg/kg BF for 4 weeks. The binding of 3H-QNB (quinuclidinyl benzilate) on mACh-R, 125I-CYP (iodocyanopindolol) on β-AdR and 3H-imipramine on imipramine binding sites decreased by 60, 20 and 70% in the presence of 1 μM BF, respectively, while the addition of 1 μM BF inhibited MAO activity by about 50%. However, CAT and AChE activities were not inhibited by BF.