Related Experiment Video
Updated: Aug 9, 2025

Whole-cell Patch-clamp Recordings from Morphologically- and Neurochemically-identified Hippocampal Interneurons
Published on: September 30, 2014
Insulin facilitates synaptic transmission via gap junctions between fast-spiking interneurons in the rat insular
Satoshi Kosukegawa1,2, Yuka Nakaya1,3, Satomi Kobayashi1,4
1Department of Pharmacology, Nihon University School of Dentistry.
Purpose:
Inhibitory synaptic currents from fast-spiking neurons (FSNs), a typical gamma-aminobutyric acid (GABA)ergic interneuron in the cerebral cortex, to pyramidal neurons are facilitated by insulin. FSNs frequently show electrical synapses to FSNs, however, the effect of insulin on these electrical synapses is unknown. The aim of this study was to evaluate effects of insulin on electrical synaptic potentials between FSNs.
Methods:
Electrical synaptic potentials via gap junctions between FSNs were recorded to examine how insulin modulates these potentials in the rat insular cortex (IC).
Results:
Bath application of insulin (10 nM), which increases the spike firing rate of pyramidal neurons and unitary inhibitory postsynaptic currents recorded from FSN to pyramidal neuron connections, slightly but significantly increased electrical synaptic currents. The mean ratio of electrical synapses, the coupling coefficient that is obtained by postsynaptic voltage responses divided by presynaptic voltage amplitude, was 8.3 ± 1.1% in control and 9.2 ± 1.1% (n = 14) during 10 nM insulin application. Input resistance and voltage responses to large hyperpolarizing currents (-140 pA) were not changed by insulin.
Conclusion:
These results suggest that insulin facilitates spike synchronization by increasing electrical synaptic currents via gap junctions of GABAergic FSNs in the IC.
Related Concept Videos
Insulin Secretory Vesicles
Glucose Homeostasis: Pancreatic Islets and Insulin Secretion
Insulin and C-peptide are...
Electrical Synapses
Gap junctions allow the current to pass directly from one cell to the next. In contrast, in the chemical synapse, the neurotransmitters carry the information through the synaptic cleft from one neuron to the next. They consist of two...
Synaptic Signaling
Most synapses are chemical, meaning an electrical impulse or action potential spurs the release of chemical messengers called neurotransmitters. The neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is the postsynaptic neuron.
The presynaptic neuron fires an action potential that...
The Role of Ion Channels in Neuronal Computation
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential....
Overview of Synapses

