Differential recruitment of N-, P- and Q-type voltage-operated calcium channels in striatal dopamine release evoked by 'regular' and 'burst' firing.
This study used the peptides omega-conotoxin GVIA, omega-agatoxin IVA and omega-conotoxin MVIIC, singly and in combination, to investigate the relative involvement of N-, P- and Q-type voltage-operated calcium channels in the control of striatal dopamine release. Electrically stimulated dopamine release was measured by fast cyclic voltammetry at carbon fibre microelectrodes in rat striatal slices. The contribution of these channel subtypes was compared in dorsolateral and medial neostriatum for 'regular' (discrete) and 'burst' stimulation modalities. In dorsolateral neostriatum, a role for N-, P- and Q-type channels was demonstrated for discrete stimulations, whilst at least one other unidentified channel was also involved in dopamine release on 'burst' stimulations. Similarly, in the medial axis of the neostriatum, N-, P- and Q-type channels were involved in dopamine release for discrete stimulations, and N-, Q- and at least one other channel type for 'burst' stimulations. However, blockade of P-type channels had no effect on dopamine release for 'burst' stimulations in the medial axis. In both regions and stimulation paradigms, N-type channels played a greater role than P/Q-type channels. In the medial axis of the neostriatum there was a smaller contribution by N- and P-type channels and the unidentified component, but a greater Q-type contribution to DA release. 'Burst' stimulations induced a lesser involvement of N- and P-type channels than discrete stimulations, and a greater role of the unidentified component. In summary, this study suggests that there is heterogeneity in the distribution of functional voltage-operated calcium channel subtypes in the neostriatum, and differences in subtype recruitment for different firing patterns.
Phillips
P E
PE
Neurotransmission Laboratory, Academic Department of Anaesthesia and Intensive Care, Saint Bartholomew's and the Royal London School of Medicine and Dentistry, Royal London Hospital, Whitechapel, E1 1BB, London, UK.
Stamford
J A
JA
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D020864:Calcium Channels, N-Type / Q000187:drug effects / Q000378:metabolism*; D020865:Calcium Channels, P-Type / Q000187:drug effects / Q000378:metabolism*; D020907:Calcium Channels, Q-Type / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D004558:Electric Stimulation / Q000379:methods; D008297:Male; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020867:omega-Agatoxin IVA / Q000494:pharmacology; D020866:omega-Conotoxin GVIA / Q000494:pharmacology; D020960:omega-Conotoxins / Q000494:pharmacology
D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type; D020867:omega-Agatoxin IVA; D020960:omega-Conotoxins; C075851:omega-conotoxin-MVIIC; D020866:omega-Conotoxin GVIA; D004298:Dopamine