Changes in cardiac innervation during maturation in long-term diabetes

Area of Science:

• Cardiovascular Research
• Diabetology
• Neuropathology

Background:

• Diabetic autonomic neuropathy, a common diabetes mellitus complication, increases cardiovascular mortality risk.
• Mechanisms of cardiac innervation changes in diabetes remain unclear.
• Understanding these changes is crucial for managing diabetic heart complications.

Purpose of the Study:

• To quantitatively assess changes in intra-myocardial nerve terminals in diabetic rat hearts.
• To investigate age-related and time-dependent alterations in cardiac innervation.
• To compare nerve fiber density between diabetic and control rats.

Main Methods:

• Male Sprague-Dawley rats were induced with diabetes using streptozotocin (STZ).
• Cardiac tissue sections from five areas were analyzed at 2 weeks, 2 months, 6 months, and 12 months post-induction.
• Immunohistochemistry using protein gene product 9.5 (PGP 9.5) visualized nerve fibers.

Main Results:

• A significant increase in total cardiac nerve fibers was observed at 2 weeks and 2 months post-diabetes induction in diabetic rats compared to controls.
• Cardiac innervation density showed dynamic changes over time in both control and diabetic rats.
• No consistent differences in nerve fiber quantity were found across different heart regions within age groups.

Conclusions:

• Cardiac innervation undergoes dynamic, time-dependent changes in both healthy and diabetic states.
• Diabetic rats exhibit a significant, early increase in intra-myocardial nerve fiber density.
• These findings offer novel insights into the pathophysiology of diabetic cardiac neuropathy.