Alpha-2 noradrenergic receptor activation inhibits the hyperpolarization-activated cation current (Ih) in neurons of the ventral tegmental area.
Enviado por Francisco Mariano Arencibia-Albi... el
Título | Alpha-2 noradrenergic receptor activation inhibits the hyperpolarization-activated cation current (Ih) in neurons of the ventral tegmental area. |
Publication Type | Journal Article |
Year of Publication | 2010 |
Autores | Inyushin, MU, Arencibia-Albite, F, Vázquez-Torres, R, Vélez-Hernández, ME, Jiménez-Rivera, CA |
Journal | Neuroscience |
Volume | 167 |
Issue | 2 |
Pagination | 287-97 |
Date Published | 2010 May 5 |
ISSN | 1873-7544 |
Palabras clave | Action Potentials, Adrenergic alpha-2 Receptor Agonists, Animals, Calcium, Clonidine, Cyclic AMP, Cyclic Nucleotide-Gated Cation Channels, Dopamine, Female, Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels, Male, Neurons, Potassium Channels, Protein Kinase C, Rats, Ventral Tegmental Area |
Abstract | The ventral tegmental area (VTA) is the source of dopaminergic projections innervating cortical structures and ventral forebrain. Dysfunction of this mesocorticolimbic system is critically involved in psychiatric disorders such as addiction and schizophrenia. Changes in VTA dopamine (DA) neuronal activity can alter neurotransmitter release at target regions which modify information processing in the reward circuit. Here we studied the effect of alpha-2 noradrenergic receptor activation on the hyperpolarization-activated cation current (I(h)) in DA neurons of the rat VTA. Brain slice preparations using whole-cell current and voltage-clamp techniques were employed. Clonidine and UK14304 (alpha-2 receptor selective agonists) were found to decrease I(h) amplitude and to slow its rate of activation indicating a negative shift in the current's voltage dependence. Two non-subtype-selective alpha-2 receptor antagonists, yohimbine and RS79948, prevented the effects of alpha-2 receptor activation. RX821002, a noradrenergic antagonist specific for alpha-2A and alpha-2D did not prevent I(h) inhibition. This result suggests that clonidine might be acting via an alpha-2C subtype since this receptor is the most abundant variant in the VTA. Analysis of a second messenger system associated with the alpha-2 receptor revealed that I(h) inhibition is independent of cyclic AMP (cAMP) and resulted from the activation of protein kinase C. It is suggested that the alpha-2 mediated hyperpolarizing shift in I(h) voltage dependence can facilitate the transition from pacemaker firing to afferent-driven burst activity. This transition may play a key role on the changes in synaptic plasticity that occurs in the mesocorticolimbic system under pathological conditions. |
DOI | 10.1016/j.neuroscience.2010.01.052 |
Alternate Journal | Neuroscience |
PubMed ID | 20122999 |
PubMed Central ID | PMC2854519 |
Grant List | 1SC1GM084854-01 / GM / NIGMS NIH HHS / United States GM-08224 / GM / NIGMS NIH HHS / United States R25 GM061838-10 / GM / NIGMS NIH HHS / United States R25 GM061838-11 / GM / NIGMS NIH HHS / United States R25-GM061838 / GM / NIGMS NIH HHS / United States SC1 GM084854 / GM / NIGMS NIH HHS / United States SC1 GM084854-01 / GM / NIGMS NIH HHS / United States |