Heterogeneity in low voltage-activated Ca2+ channel-evoked Ca2+ responses within neurons of the thalamic paraventricular nucleus.
Low voltage-activated Ca2+ channels (LVA or T-type Ca2+ channels) are crucial to burst firing and oscillations in thalamocortical relay cells and are exhibited by neurons in the paraventricular nucleus of thalamus (PVT), a dorsal midline nucleus deemed important in the neural representation of motivational behaviours. We used a functional approach (whole-cell patch-clamp electrophysiology combined with confocal laser scanning microscopy) to analyse the spatial distribution of LVA Ca2+ channel-evoked Ca2+ transients in PVT neurons. We observed that the magnitude of LVA Ca2+ channel-evoked Ca2+ transients was significantly greater in proximal dendrites (located up to 20 microm from the soma) than in the soma. In addition, the magnitudes of these Ca2+ transients varied significantly not only among different dendrites of the same cell but also within individual dendrites. These findings suggest that LVA Ca2+ channels are expressed (i) predominantly on the proximal dendrites and (ii) heterogeneously within individual dendrites of PVT neurons. The spatial characteristics of dendritic LVA Ca2+ channels in PVT neurons suggest that these channels may regulate burst firing by modulating dendritic afferent inputs.
Richter
Trevor A
TA
Department of Neuroscience, Ottawa Health Research Institute, 725 Parkdale Avenue, Ottawa, Ontario K1Y 4E9, Canada. trichter@ohri.ca
Kolaj
Miloslav
M
Renaud
Leo P
LP
D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D003712:Dendrites / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D020644:Midline Thalamic Nuclei / Q000166:cytology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D017208:Rats, Wistar
D015220:Calcium Channels; D002118:Calcium