Altered non-adrenergic non-cholinergic neurotransmission in gastric fundus from streptozotocin-diabetic rats

The influence of streptozotocin-induced diabetes has been investigated on responses to non-adrenergic, non-cholinergic (NANC) nerve stimulation in rat gastric fundus. NANC relaxations in precontracted muscle strips from diabetic rats were smaller than those from control rats. In addition, the relaxations in diabetic but not control rats were followed by rapidly-developing frequency-dependent contractions. Ln the presence of alpha-chymotrypsin and N-G-nitro-L-arginine methyl ester (L-NAME), the NANC contractions were markedly enhanced in diabetic rats. Treatment with the aldose reductase inhibitor, sorbinil, did not affect NANC relaxations or contractions in tissues from diabetic rats, and responses remained significantly different from those from control rats. The findings suggest that diabetes impairs relaxations to NANC nerve stimulation in the rat gastric fundus, and that a contractile NANC neurotransmitter(s) is released in diabetic rats. The results also suggest that diabetes-induced alterations in the NANC nerve response are not caused by increased activity of the aldose reductase pathway. (C) 2000 Elsevier Science B.V. All rights reserved.