Passive Membrane Properties and Spike Characteristics in a Pair of Identified Electrically Coupled Lymnaea stagnalis Neurons under Long-Term Experimental Hyperglycemia

• Published in: Journal of evolutionary biochemistry and physiology Vol. 59; no. 2; pp. 369 - 381
• Main Authors: Sidorov, A. V., Shadenko, V. N.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-03-2023; Springer Nature B.V
• Subjects: Animal Physiology; Biochemistry; Biomedical and Life Sciences; Electrical properties; Evolutionary Biology; Experimental Papers; Firing pattern; Glucose; Hyperglycemia; Life Sciences; Lymnaea stagnalis; Membrane capacitance; Membrane potential; Membrane resistance; Neurosecretory cells; Synchronization; mollusks; homeostasis; glucose; nervous system; invertebrates; electrical synapse
• ISSN: 0022-0930; 1608-3202
• DOI: 10.1134/S0022093023020060

Microelectrode technique was used to study the responses of the electrically coupled giant peptidergic VD1 and RPaD2 neurons within the isolated CNS of the pond snail
Lymnaea stagnalis
to prolonged (≥ 2 h) exposure to high D-glucose concentrations (10 mM). It has been established that passive membrane properties of the RPaD2, compared to VD1, undergo significant changes under experimental hyperglycemia—a decrease in membrane resistance (
R
m
) accompanied by an increase in membrane capacitance (
C
m
) and time constant (τ
m
). Despite the invariance of VD1 and RPaD2 firing rates, the VD1 membrane depolarized, while the RPaD2 membrane potential did not vary significantly. Modifications in temporal, but not amplitude, characteristics of VD1 and RPaD2 action potentials were similar and resulted in a prolongation of their main phases (rising, falling, undershoot). It is assumed that the “unification” of membrane electrical properties in
L. stagnalis
CNS neurosecretory neurons (VD1/RPaD2) under hyperglycemia plays an adaptive role, aimed at overcoming the possible desynchronization of their spike activity due to electrical decoupling initiated by a high glucose content in the interstitial space.