| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Physiology and Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
2 Pain Management Research Institute, University of Sydney at the Royal North Shore Hospital, St Leonards, Sydney NSW, Australia
3 Department of Physiology and Pharmacology, School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; Prince of Wales Medical Research Institute, University of New South Wales, Randwick, SYDNEY NSW, Australia
* To whom correspondence should be addressed. E-mail: p.osborne{at}usyd.edu.au.
The ventral pallidum in rat is a basal forebrain structure that contains neurons that project in the limbic striatopallidal circuitry, and magnocellular cholinergic corticopetal neurons. As 5-HT terminals on dorsal raphe projections form close appositions with these neurons, we made patch clamp recordings in immature rat brain slices to determine if they are modulated by postsynaptic 5-HT receptors. Inward currents were predominantly induced by 5-HT in non-cholinergic neurons, which were distinguished from cholinergic neurons by immunohistochemical and electrophysiological criteria. The inward current induced by 5-HT was mimicked and occluded when adenylyl cyclase was stimulated with forskolin, and was almost abolished when h-currents in non-cholinergic neurons were blocked with cesium. Consistent with 5-HT7 receptor activation of h-curents via cAMP in other brain regions, we found inward currents were mimicked by the mixed 5-HT1 / 5-HT7 agonists 5-methoxytryptamine, and by 5-carboxamidotryptamine (5-CT), which was more potent than 5-HT. In contrast, 5-HT1-preferring 8-OH-DPAT was a weak partial agonist, and the 5-HT1-selective antagonist pindolol had no effect. However, despite this profile, antagonists that bind at the 5-HT7 receptor only partly reduced the agonist inward current (SB-269970 and clozapine), or had no effect (mianserin and pimozide). We found in cholinergic neurons that 5-HT predominantly induced hyperpolarizing currents, which were carried by potassium channels, and were smaller than currents induced by 8-OH-DPAT and 5-CT. We conclude from this study that ascending 5-HT projections from the dorsal raphe could have direct and opposite effects on the activities of neurons within the limbic striato-pallidal and cholinergic corticopetal circuitry in the ventral pallidum.
This article has been cited by other articles:
|
|
 |
|
  K. Hashimoto and H. Kita Serotonin Activates Presynaptic and Postsynaptic Receptors in Rat Globus Pallidus J Neurophysiol, April 1, 2008; 99(4): 1723 - 1732. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Kita, S. Chiken, Y. Tachibana, and A. Nambu Serotonin Modulates Pallidal Neuronal Activity in the Awake Monkey J. Neurosci., January 3, 2007; 27(1): 75 - 83. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Liu and L. M. Jordan Stimulation of the Parapyramidal Region of the Neonatal Rat Brain Stem Produces Locomotor-Like Activity Involving Spinal 5-HT7 and 5-HT2A Receptors J Neurophysiol, August 1, 2005; 94(2): 1392 - 1404. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. A. Otmakhova, J. Lewey, B. Asrican, and J. E. Lisman Inhibition of Perforant Path Input to the CA1 Region by Serotonin and Noradrenaline J Neurophysiol, August 1, 2005; 94(2): 1413 - 1422. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
