Jpn. J. Pharmacol. 72, 317-324 (1996)
Effects of Tri-, Di- and Monobutyltin on Synaptic Parameters of the
Cholinergic System in the Cerebral Cortex of Mice
Haruo Kobayashi (1), Tadahiko Suzuki (1), Yoshinori Kasashima (1), Akira
Motegi (1), Itaru Sato (2), Naonori Matsusaka (2), Naoko Ono (1), Akemi
Miura (1), Fumiya Saito (3) and Shin-ya Saito (1)
Departments of (1) Veterinary Pharmacology and (2) Veterinary Public
Health, Faculty of Agriculture, Iwate University, Ueda, Morioka 020, Japan
(3) Koiwai Farm Co., Shizukuishi, Iwate 020-05, Japan
Abstract: Triorganotin compounds like tributyltin have been reported
to be biodegraded to diorganotin, monoorganotin and then inorganic tin in
animals after they have been ingested. Effects of tributyltin, dibutyltin
and monobutyltin on various cholinergic parameters that are involved in
synaptic transmission in the mouse cerebral cortex were investigated in
vitro. Tributyltin and dibutyltin, but not monobutyltin, inhibited the activity
of choline acetyltransferase, both the high-affinity and low-affinity uptakes
of choline into synaptosomes, and the binding of [3H]quinuclidinyl benzilate
to muscarinic acetylcholine receptors. Tributyltin and dibutyltin, but not
monobutyltin, had a slightly suppressive effect on the K+-induced release
and synthesis of acetylcholine in slices of the cortex. All three butyltins
at concentrations from 10-6 to 10-4 M had no effect on the activity of acetylcholinesterase.
The extent of the inhibitory effects on the cholinergic parameters, apart
from the activity of acetylcholinesterase, was slightly greater in the case
of tributyltin than dibutyltin, in particularly at the highest concentration
(10-4 M) tested. Therefore, it is concluded that tributyltin metabolites
inhibit various parameters of cholinergic activity with a potency ranking
of tributyltin > dibutyltin > monobutyltin.
Keywords: Cholinergic parameter, Dibutyltin, Monobutyltin, Organotin,
Tributyltin
Copyright© The Japanese Pharmacological Society 1996
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