Somatostatin modulates Ca2+ currents in neostriatal neurons

Area of Science:

• Neuroscience
• Neuropharmacology
• Cellular Electrophysiology

Background:

• Somatostatin is a neuropeptide synthesized and released by aspiny interneurons in the neostriatum.
• The precise postsynaptic actions of somatostatin on neostriatal neurons remain incompletely understood.

Purpose of the Study:

• To investigate the direct postsynaptic effects of somatostatin on medium-sized rat neostriatal neurons.
• To identify the specific calcium channel subtypes modulated by somatostatin and their role in neuronal excitability.

Main Methods:

• Electrophysiological recordings were performed on rat neostriatal neurons.
• The effects of somatostatin (1 microM) on calcium action potentials and calcium currents were measured.
• Pharmacological tools, including somatostatin receptor antagonist (CPP-1) and various calcium channel blockers, were utilized.

Main Results:

• Somatostatin (1 microM) significantly reduced calcium action potentials (24%) and calcium currents (35%) in neostriatal neurons.
• These effects were mediated via somatostatin receptors and primarily involved P/Q-type and N-type calcium channels.
• Somatostatin application decreased the afterhyperpolarizing potential amplitude (39%), leading to irregular neuronal firing.

Conclusions:

• Somatostatin exerts a direct postsynaptic effect on neostriatal neurons by activating somatostatin receptors.
• This action modulates non-L-type calcium channels, specifically P/Q-type, influencing neuronal excitability and firing patterns.
• Somatostatin and its analogues may play a significant role in regulating motor functions within the basal ganglia.