ALTERATIONS IN URINARY-BLADDER SYNAPTOSOMAL NEUROTRANSMITTER CONCENTRATIONS IN 2-WEEK STREPTOZOTOCIN-INDUCED DIABETIC RATS

Three-month-old male Wistar rats were rendered diabetic with a single intravenous injection of streptozotocin (60 mg/kg body weight). Two we eks after induction of diabetes, synaptosome-rich fractions were prepa red from urinary bladder tissue homogenate of the diabetic rats and co ntrol rats by differential centrifugation (1000 x g, 17 000 x g and 10 0 000 x g) with discontinuous sucrose gradient. Synaptosomal acetylcho line, norepinephrine, epinephrine and dopamine were measured by the me thod of high-performance liquid chromatography. The respective neurotr ansmitter concentrations for the diabetic rats were 1537.8 +/- 65.3, 4 757.7 +/- 361.9, 3720.7 +/- 276.1, and 2447.8 +/- 196.8 pmol/mg synapt osomal protein, respectively; those for the control rats were 338.1 +/ - 25.0, 1009.0 +/- 54.6, 645.3 +/- 52.2, and 1426.1 +/- 123.9 pmol/mg protein, respectively. Thus, the synaptosomal concentrations for all t he measured neurotransmitters were significantly higher in the diabeti c rats (P < 0.05 for each comparison). In conclusion, it has been demo nstrated that the vesicle-bound acetylcholine and catecholamines in th e synaptosome-rich fraction of the urinary bladder were significantly increased in 2-week diabetic rats. This finding would suggest impaired neurotransmitter release from both the bladder sympathetic and parasy mpathetic efferent nerve endings in early streptozotocin-induced diabe tes.