Bacillus anthracis lethal toxin induces complex changes in sympathetic nerve discharge regulation

Area of Science:

• Physiology
• Neuroscience
• Pathology

Background:

• Bacillus anthracis lethal toxin (LeTx) is known to affect cardiovascular regulation.
• Previous studies indicate LeTx alters blood pressure and sympathetic nerve discharge (SND).

Purpose of the Study:

• To investigate the effects of LeTx on peripheral and visceral sympathetic nerve discharge.
• To determine if sympathetic neural circuits remain functional during the hypotensive phase of LeTx-induced shock.

Main Methods:

• Infusion of LeTx in a model system.
• Measurement of peripheral (lumbar) and visceral (renal) SND.
• Application of hypoxia and hypercapnia during LeTx-induced hypotension.

Main Results:

• LeTx infusions caused an initial increase in SND, followed by a reduction in both lumbar and renal SND.
• The reduction in lumbar SND was less pronounced than in renal SND.
• Hypoxia and hypercapnia during hypotension successfully increased both lumbar and renal SND.

Conclusions:

• LeTx induces complex changes in SND, characterized by initial activation and subsequent inhibition.
• Sympathetic neural circuits retain the capacity for activation even during the circulatory shock phase induced by LeTx.
• These findings highlight the dynamic neural responses during B. anthracis septicemia.