Ž . European Journal of Pharmacology 390 2000 7–13 www.elsevier.nlrlocaterejphar Effects of CI-1002 and CI-1017 on spontaneous synaptic activity and on the nicotinic acetylcholine receptor of Torpedo electric organ Esteve Ros, Jordi Aleu, Jordi Marsal, Carles Solsona ) Laboratori de Neurobiologia Cellular i Molecular, Departament de Biologia Cellular i Anatomia Patologica, Facultat de Medicina, Hospital de BellÕitge, ` UniÕersitat de Barcelona, Campus de BellÕitge, PaÕello de GoÕern, Feixa Llarga s r n E-08907, L’Hospitalet de Llobregat, Spain ´ Received 28 June 1999; received in revised form 15 December 1999; accepted 21 December 1999 Abstract w x Ž . The effect of azepino 2,1-b quinazoline 1,3-dichloro-6,7,8,9,10,12-hexahydro-, mono-hydrochloride CI-1002 , a tacrine derivative, w x w Ž . x w Ž .x Ž . and 1-azabicyclo 2.2.1 heptan-3-one, O- 3- methoxyphenyl -2-propynyl oxime R- Z -2-butenedioate CI-1017 , a muscarinic M recep- 1 tor agonist, on spontaneous synaptic activity was investigated by measuring amplitude, rise time, velocity of rising, half-width, and Ž . electrical charge of miniature endplate potentials m.e.p.p. recorded extracellularly in Torpedo electric organ fragments. The effect of CI-1002 and CI-1017 on the nicotinic acetylcholine receptor was investigated by measuring the current induced by acetylcholine in Xenopus laeÕis oocytes transplanted with membranes from Torpedo electric organ. CI-1002, at a concentration of 1 mM, altered the Ž . Ž . m.e.p.p. by increasing the amplitude from 1.08 "0.01 to 2.76 "0.03 mV , rise time from 0.700 "0.006 to 1.02 "0.01 ms , rising rate Ž . Ž . Ž from 1.79 "0.02 to 3.45 "0.05 mVrms , half-width from 0.990 "0.008 to 2.40 "0.02 ms , and electrical charge from 304 "4 to . Ž 784 "11 mV s . CI-1017, at a concentration of 1 mM, altered the m.e.p.p. by decreasing the amplitude from 1.08 "0.01 to . Ž . Ž . 0.650 "0.007 mV , rise time from 0.700 "0.006 to 0.530 "0.007 ms , rising rate from 1.79 "0.02 to 1.53 "0.02 mVrms , Ž . Ž . half-width from 0.990 "0.008 to 0.670 "0.007 ms , and electrical charge from 304 "4 to 75 "1 mV s . CI-1002 inhibited the acetylcholine-induced current of nicotinic acetylcholine receptors with an IC of 3.4 "0.3 mM. CI-1017 inhibited the acetylcholine-in- 50 duced current of nicotinic acetylcholine receptors with an IC of 0.8 "0.1 mM. These results indicate that, although both drugs 50 interacted negatively with nicotinic acetylcholine receptors, CI-1002 overcame this inhibition by recruiting more acetylcholine to build a quantum. q 2000 Elsevier Science B.V. All rights reserved. Ž . Ž Keywords: Alzheimer’s disease; Cholinergic; Exocytosis; Neuromuscular junction; Oocyte; Synaptic vesicle; Tacrine; Torpedo marmorata ; Xenopus . laeÕis 1. Introduction It is generally accepted that even though Alzheimer’s disease implicates a general loss of neurotransmitters, the decrease in brain acetylcholine levels is directly related to Ž severe cognitive dysfunction Davies and Maloney, 1976; . Bartus et al., 1982; Coyle et al., 1983 . A straightforward procedure to maintain high levels of endogenous acetyl- choline is intended to inhibit the acetylcholinesterases, which hydrolyse acetylcholine in the synaptic cleft. Physostigmine and tacrine, both anticholinesterasic agents, Ž have been used in clinical trials with partial success see Davies and Maloney, 1976; Davis et al., 1978; Weinstock, . 1995; Giacobini, 1998 for review . ) Corresponding author. Tel.: q34-93-402-4279; fax: q34-93-403- 5810. Ž . E-mail address: solsona@bellvitge.bvg.ub.es C. Solsona . Another strategy for the therapy of Alzheimer’s disease patients is to mimic the action of acetylcholine directly upon the receptors by using muscarinic and nicotinic acetylcholine receptor agonists. Muscarinic M receptor 1 agonists are a class of drugs that are currently being developed but their clinical use is still limited by side Ž . effects. see Giacobini, 1997 for review . New nicotinic receptor agonists that show none of the adverse side effects of nicotine, which limit its clinical use, are likewise Ž . being investigated see Giacobini, 1996 for review . The direct measurement of the quantal release in the central nervous system, and the mean life of acetylcholine molecules have not been established. An alternative exper- imental model is the vertebrate neuromuscular junction, in which the quantal nature of acetylcholine release can be recorded. The electric organs of Elasmobranchs are embry- ologically derived from the skeletal muscle and have a great number of motor nerve endings. Indeed, there are 0014-2999r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0014-2999 99 00911-5