| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Journal of Neurophysiology, Vol 76, Issue 3 1968-1981, Copyright © 1996 by APS
ARTICLES |
R. H. Farkas, P. Y. Chien, S. Nakajima and Y. Nakajima
Department of Anatomy and Cell Biology, University of Illinois at Chicago, College of Medicine 60612, USA.
1. A widespread mechanism of slow excitation throughout the nervous system involves overlapping changes in nonselective ion conductance and K+ conductance. We used whole cell patch-clamp recording to characterize such a nonselective conductance induced by neurotensin (NT) and other neurotransmitters in immunocytochemically identified dopaminergic neurons cultured from the rat ventral tegmental area (VTA). 2. The NT-induced inward current consisted of an initial peak and later "hump." The response was blocked reversibly by the nonpeptide NT-receptor antagonist SR48692, suggesting that it resulted from activation of NT receptors. 3. The channel was almost equally permeable to Na+ and K+, as determined from the reversal potential shift upon switching from Na+- to K(+)-containing external solution. The permeability of Cs+ was similar to that of Na+, as determined from the zero-current equation and average reversal potential in the 75 mM Na+ solution. Cl- was not significantly permeable. 4. In Ca(2+)-free external solution, the NT-induced current showed a fourfold increase in amplitude, and in high Mg2+ (20 mM) external solution, the NT-induced current showed an 80% decrease in amplitude, suggesting that external Ca2+ and Mg2+ could block the nonselective conductance. 5. The NT response was unaffected by loading the neurons with either the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or with 1 mM ca2+. The nonselective conductance was therefore not Ca2+ activated. 6. Loading the neurons with cyclic GMP or cyclic AMP (each with the phosphodiesterase inhibitor isobutyl-methylxanthine) did not affect the NT response. The NT-induced nonselective conductance was therefore not cyclic nucleotide-activated. 7. The latency of the NT response was long (> or = 185 ms, average 406 ms, 30 degrees C), indicating that NT did not induce the conductance through ligand-gated channels. Thus, NT activated a slow nonselective cation conductance. 8. Neurokinin B, a metabotropic glutamate agonist, and muscarine elicited responses similar to the NT response. The NT response could be elicited after desensitizing the responses to these other neurotransmitters, indicating receptor specificity in the activation of the nonselective conductance.
This article has been cited by other articles:
|
|
 |
|
  H. Huang and A. N. van den Pol Rapid Direct Excitation and Long-Lasting Enhancement of NMDA Response by Group I Metabotropic Glutamate Receptor Activation of Hypothalamic Melanin-Concentrating Hormone Neurons J. Neurosci., October 24, 2007; 27(43): 11560 - 11572. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Koike-Tani, J. M Collins, T. Kawano, P. Zhao, Q. Zhao, T. Kozasa, S. Nakajima, and Y. Nakajima Signal transduction pathway for the substance P-induced inhibition of rat Kir3 (GIRK) channel J. Physiol., April 15, 2005; 564(2): 489 - 500. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. V. Hoang, P. Zhao, S. Nakajima, and Y. Nakajima Orexin (Hypocretin) Effects on Constitutively Active Inward Rectifier K+ Channels in Cultured Nucleus Basalis Neurons J Neurophysiol, December 1, 2004; 92(6): 3183 - 3191. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Wu, L. Zaborszky, T. Hajszan, A. N. van den Pol, and M. Alreja Hypocretin/Orexin Innervation and Excitation of Identified Septohippocampal Cholinergic Neurons J. Neurosci., April 7, 2004; 24(14): 3527 - 3536. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. St-Gelais, M. Legault, M.-J. Bourque, P.-P. Rompre, and L.-E. Trudeau Role of Calcium in Neurotensin-Evoked Enhancement in Firing in Mesencephalic Dopamine Neurons J. Neurosci., March 10, 2004; 24(10): 2566 - 2574. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R.-J. Liu, A. N. van den Pol, and G. K. Aghajanian Hypocretins (Orexins) Regulate Serotonin Neurons in the Dorsal Raphe Nucleus by Excitatory Direct and Inhibitory Indirect Actions J. Neurosci., November 1, 2002; 22(21): 9453 - 9464. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Burlet, C. J. Tyler, and C. S. Leonard Direct and Indirect Excitation of Laterodorsal Tegmental Neurons by Hypocretin/Orexin Peptides: Implications for Wakefulness and Narcolepsy J. Neurosci., April 1, 2002; 22(7): 2862 - 2872. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. B. Binder, B. Kinkead, M. J. Owens, and C. B. Nemeroff Neurotensin and Dopamine Interactions Pharmacol. Rev., December 1, 2001; 53(4): 453 - 486. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P.-Y. Chien, R. H. Farkas, S. Nakajima, and Y. Nakajima Single-channel properties of the nonselective cation conductance induced by neurotensin in dopaminergic neurons PNAS, December 10, 1996; 93(25): 14917 - 14921. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Ito and D. Dulon Nonselective cation conductance activated by muscarinic and purinergic receptors in rat spiral ganglion neurons Am J Physiol Cell Physiol, May 1, 2002; 282(5): C1121 - C1135. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
