Globus pallidus receives, from dorsal neostriatum, a dense enkephalinergic innervation whose role is still uncertain. We examined the possibility that the activation of mu, delta or k opioid receptors modulate high-voltage-activated calcium currents in isolated GP neurons. Neither dynorphin nor DPEPE inhibited calcium current, whilst DAMGO produced a small (-16%) but consistent response, selectively antagonized by CTOP. The mu-mediated modulation required the activation of G-proteins but was voltage-independent. The pre-incubation in omega-conotoxinVIA abolished the response, implying the involvement of N-type calcium channels. These findings suggest that enkephalin may exert a direct influence on GP excitability also through post-synaptic effects. In degenerative conditions as Parkinsonism, an excessive stimulation of mu binding sites might induce a pathological inhibition of calcium signals, thus contributing to modify the GP firing pattern and transmitter release.

Stefani, A. (2001). The activation of mu opioid receptors promotes a small modulation of calcium currents in rat pallidal neurons. BRAIN RESEARCH, 897(1-2), 207-212.

The activation of mu opioid receptors promotes a small modulation of calcium currents in rat pallidal neurons

STEFANI A
2001-04-06

Abstract

Globus pallidus receives, from dorsal neostriatum, a dense enkephalinergic innervation whose role is still uncertain. We examined the possibility that the activation of mu, delta or k opioid receptors modulate high-voltage-activated calcium currents in isolated GP neurons. Neither dynorphin nor DPEPE inhibited calcium current, whilst DAMGO produced a small (-16%) but consistent response, selectively antagonized by CTOP. The mu-mediated modulation required the activation of G-proteins but was voltage-independent. The pre-incubation in omega-conotoxinVIA abolished the response, implying the involvement of N-type calcium channels. These findings suggest that enkephalin may exert a direct influence on GP excitability also through post-synaptic effects. In degenerative conditions as Parkinsonism, an excessive stimulation of mu binding sites might induce a pathological inhibition of calcium signals, thus contributing to modify the GP firing pattern and transmitter release.
6-apr-2001
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore MED/26 - NEUROLOGIA
English
Animals; Calcium; Enkephalin, Leucine-2-Alanine; Receptors, Opioid, mu; Calcium Channel Blockers; Dynorphins; Calcium Channels, N-Type; Rats; Patch-Clamp Techniques; omega-Conotoxin GVIA; Neurons; Rats, Wistar; Membrane Potentials; Analgesics, Opioid; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Globus Pallidus; Male
Stefani, A. (2001). The activation of mu opioid receptors promotes a small modulation of calcium currents in rat pallidal neurons. BRAIN RESEARCH, 897(1-2), 207-212.
Stefani, A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/218392
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