The cardiac ganglia in streptozotocin-induced diabetic rats.

The ultrastructure of the cardiac ganglia of streptozotocin-induced diabetic rats was studied at survival times of 3 and 7 days, 1, 3, 6, 9 and 12 months. At 3-7 days post-induction, some intracardiac neurons showed an overall increase in electron density, with the dendrites darkening first. Some of the affected dendrites appeared jet black and their intracytoplasmic organelles were hardly distinguishable except for some swollen mitochondria. Both electron dense and lucent types of degenerating axon terminals were observed in the interstitial spaces. Several myelinated and unmyelinated axons also showed early signs of degeneration. At 1-6 months post-induction, numerous myelinated and unmyelinated axons were shown to be degenerated. The majority of the intracardiac neurons appeared to be normal. Numerous macrophages containing phagosomes were found in the interstitial spaces. At 9-12 months post-induction, macrophages containing engulfed debris were still commonly observed amongst the neuronal profiles, which appeared to be morphologically normal. It is concluded that degenerative changes occur in the cardiac ganglia of streptozotocin-induced diabetic rats and that these changes appear to be both progressive and prolonged.