Hypertrophic neurons innervating the urinary bladder and colon of the streptozotocin-diabetic rat

Female rats were made diabetic with an intravenous injection of streptozotocin (STZ) producing bladder hypertrophy. Using fluorescent dyes injected into the bladder or the colon, we have measured the size of neurons in various ganglia associated with these organs in control and STZ-diabetic rats. These include (1) postganglionic neurons in the pelvic ganglion, (2) postganglionic neurons in the inferior mesenteric ganglion, (3) dorsal root ganglion neurons, (4) sympathetic chain ganglion neurons, (5) preganglionic neurons in the sacral parasympathetic nucleus, (6) motor neurons in Onuf's nucleus innervating the external urethral sphincter. In addition we have measured neurons in some of these groups for rats which have been maintained on a 5% sucrose in water and restricted food diet. In the STZ-diabetic animals only those neurons which make direct contact with the bladder or the colon were found to be hypertrophied (15-70%). In the diuretic animals, only neurons directly innervating the bladder exhibited hypertrophy. We speculate that a trophic factor transported from the organ to the neuron is responsible for this effect.