g(m1)-ganglioside and ethylcholine-aziridinium

Mustard derivatives of ethyl-choline and hemicholinium-3 have been suggested as possible specific cholinergic neurotoxins. In this study a structural analog of hemicholinium-3, a,a'-bis[di(2-chloroethyl)amino]-4,4'-2-biacetophenone (toxin 7), was added to synaptosomes prepared from the cortex, striatum or hippocampus of rat brain. Synaptosomal high affinity choline uptake (HACU) was significantly decreased in a dose-dependent manner by addition of toxin 7, while synaptosomal uptake of GABA or dopamine was not changed. Incubation of cortical synaptosomes with the monosialoganglioside GM1 prevented the decrease in HACU seen following administration of toxin 7. This preventative effect of GM1 was greater if GM1 was added prior to or concomitant with toxin 7, than if GM1 was added following toxin 7. Two newly synthesized hemicholinium-3 analogs, 4-[3'-di(2-chloroethyl)aminopropionyl]biphenyl (toxin 5) and 4-[3'-di(2-bromoethyl)aminopropionyl]biphenyl (toxin 6) caused a large decrease in HACU when added to cortical synaptosomes, this decrease was significantly greater than that seen with the same dose of toxin 7 or ethyl-choline aziridinium (AF64A). Ultrastructural changes in the synaptosomal membrane following incubation with toxin 7 or toxin 7 with GM1 were examined by electron microscopy. Development of a compound which is both a potent neurotoxin, and is specific for cholinergic neurons will allow new insights into the normal function of the cholinergic system in the CNS and provide animal models of disease states in which cholinergic degeneration is an important element.

Topics: Animals; Aziridines; Biological Transport; Biphenyl Compounds; Brain; Choline; Dopamine; Dose-Response Relationship, Drug; G(M1) Ganglioside; gamma-Aminobutyric Acid; Kinetics; Male; Microscopy, Electron; Molecular Structure; Neuromuscular Blocking Agents; Neurotoxins; Nitrogen Mustard Compounds; Rats; Rats, Wistar; Synaptosomes; Tritium

Ganglioside AGF2 attenuated both the cognitive impairments and the cholinergic hypofunction induced by ethylcholine aziridinium ion (AF64A). Adult male rats were initially trained to perform a standard radial arm maze (RAM) task. Following training, they were injected intraperitoneally with 10 mg/kg AGF2 (AF/AGF2, CSF/AGF2) or the saline vehicle (AF/SAL, CSF/SAL) for 3 days prior to and for 14 days following bilateral injection of AF64A (3 nmol/side) or artificial CSF into the lateral ventricles. AF64A (AF/SAL) impaired performance of the standard RAM task and a working memory version of the task in which various delays were imposed between the fourth and fifth arm choices. In contrast, animals that received AGF2 and AF64A (AF/AGF2) were initially impaired on the standard RAM task but rapidly recovered and were performing as well as the control groups (CSF/SAL, CSF/AGF2) by the end of training. The AF/AGF2 group, however, exhibited persistent deficits on the working memory version of the RAM task. These data demonstrate that AGF2 promotes behavioral recovery in a task-dependent manner in this model system. Neurochemical analysis revealed that AF64A produced a significant 37% decrease in hippocampal ChAT activity that was significantly attenuated, but not prevented, by prior treatment with AGF2. Thus the behavioral recovery afforded by AGF2 might be related to increased cholinergic activity in the hippocampus that is sufficient for the performance of tasks which either lack or have a minimal working memory component. An analysis of the temporal profile of AGF2-induced neurochemical recovery revealed that ChAT activity was enhanced at 20, but not 2 or 11, weeks following AF64A. Since AGF2 did not attenuate the cholinergic cell loss (35%) induced by AF64A in the medial septum these data indicate that AGF2 might have (1) enhanced sprouting of cholinergic terminals following the initial insult, (2) directly increased ChAT activity in surviving neurons, or (3) induced behavioral and neurochemical recovery through a combination of these or other mechanisms.

Topics: Acetylcholinesterase; Animals; Aziridines; Cerebral Ventricles; Choline; Choline O-Acetyltransferase; G(M1) Ganglioside; Hippocampus; Injections, Intraventricular; Learning; Male; Memory; Neuromuscular Blocking Agents; Rats; Rats, Inbred Strains; Reference Values; Space Perception

Ethylcholine mustard aziridinium ion (ECMA) was infused intracerebroventricularly (icv) to rats followed by measurement of two markers of presynaptic cholinergic neurons, choline acetyltransferase (ChAT) activity and high affinity choline transport (HAChT), in the hippocampus and cortex. Bilateral icv administration of 1, 2, or 3 nmol of ECMA per side produced dose-dependent reductions in each marker in the hippocampus, but not in the cortex, one week after treatment. Reductions of 52% and 46% for ChAT activity and HAChT, respectively, were produced in the hippocampus by 3 nmol ECMA. Measurement of these two markers at different times after icv infusion of 2 nmol ECMA/ventricle revealed that the activity of ChAT was reduced to a greater extent than was HAChT in the hippocampus 1 day and 1, 2, 4, and 6 weeks after treatment. The maximal reductions of ChAT activity and HAChT (61% and 53%, respectively) were reached between 1 and 2 weeks after ECMA administration. There was no evidence of regeneration of either marker at 4 or 6 weeks posttreatment. HAChT and ChAT activity in the cortex were not altered at any of the posttreatment times examined. ECMA-induced deficits in hippocampal ChAT activity and HAChT were not counteracted by the following treatments: (i) daily administration of GM1 ganglioside (10 mg/kg, intraperitoneally (ip)) from the day prior to infusion of ECMA until 2 weeks later; (ii) daily administration of GM1 ganglioside between 2 and 6 weeks after infusion of ECMA; and (iii) icv administration of nerve growth factor (NGF) twice per week for 2 weeks after ECMA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Aziridines; Azirines; Choline; Cholinergic Fibers; Dose-Response Relationship, Drug; G(M1) Ganglioside; Hippocampus; Injections, Intraventricular; Male; Nerve Growth Factors; Rats; Rats, Inbred Strains; Time Factors; Vitamin E