Interrelationships Between Spinal Sympathetic Preganglionic Neurons, Autonomic Systems and Electrical Synapses Formed...

Area of Science:

• Neuroscience
• Cell Biology
• Autonomic Nervous System Research

Background:

• Electrical coupling via connexin36 (Cx36) gap junctions is found in various mammalian central nervous system (CNS) neuronal populations.
• Understanding Cx36 distribution in spinal sympathetic preganglionic neurons (SPNs) is crucial for comprehending autonomic functions.

Purpose of the Study:

• To map the distribution of Cx36 in SPNs within the mammalian spinal cord.
• To investigate the developmental expression of Cx36 in SPNs.
• To explore potential synaptic inputs to SPNs from Cx36-expressing neurons.

Main Methods:

• Immunofluorescence detection of Cx36 in SPNs identified by choline acetyltransferase, nitric oxide, and peripherin markers.
• Analysis of Cx36 distribution in adult and developing mouse and rat spinal cords.
• Examination of Cx36 expression in Cx36 knockout mice and Cx36BAC::eGFP reporter mice.

Main Results:

• Dense Cx36 puncta were observed throughout the thoracic intermediolateral cell column (IML) in adult animals.
• Cx36 puncta were associated with SPN dendrites in various autonomic areas.
• Cx36 expression was present in SPNs from postnatal day 10-12, and absent in Cx36 knockout mice.
• eGFP reporter in Cx36BAC::eGFP mice localized to synaptic terminals, some contacting SPN dendrites, indicating SPNs receive input from potentially coupled neurons.

Conclusions:

• Widespread Cx36 expression in SPNs supports significant electrical coupling among these neurons.
• Electrical coupling is a key feature of SPN organization, influencing autonomic functions.
• SPNs are innervated by neurons that may also be electrically coupled, suggesting complex neural circuitries.