The lateral habenula regulates defensive behaviors through changes in 5-HT-mediated neurotransmission in the dorsal periaqueductal gray matter

Chemical stimulation of the lateral nucleus of the habenula (LHb), an area implicated in the regulation of serotonergic activity in raphe nuclei, affects the acquisition of inhibitory avoidance and escape expression of rats submitted to the elevated T-maze test of anxiety. Here, we investigated whet...

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Bibliographic Details
Published in:Neuroscience letters 2010-07, Vol.479 (2), p.87-91
Main Authors: Pobbe, Roger Luis Henschel, Zangrossi, Helio
Format: Article
Language:English
Subjects:
Animals
Antagonists
Avoidance Learning
Biological and medical sciences
Dorsal periaqueductal gray
Dorsal raphe nucleus
Fear and anxiety
Fundamental and applied biological sciences. Psychology
Habenula - physiology
Kainic Acid - pharmacology
Ketanserin - pharmacology
Lateral habenula
Male
Maze Learning - drug effects
Motor Activity - drug effects
Neurons - drug effects
Neurons - physiology
Periaqueductal Gray - drug effects
Periaqueductal Gray - physiology
Piperazines - pharmacology
Pyridines - pharmacology
Rats
Rats, Wistar
Receptor, Serotonin, 5-HT1A - physiology
Receptor, Serotonin, 5-HT2A - physiology
Receptor, Serotonin, 5-HT2C - physiology
Serotonin
Serotonin - physiology
Serotonin 5-HT1 Receptor Antagonists
Serotonin 5-HT2 Receptor Antagonists
Synaptic Transmission
Vertebrates: nervous system and sense organs
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Summary:Chemical stimulation of the lateral nucleus of the habenula (LHb), an area implicated in the regulation of serotonergic activity in raphe nuclei, affects the acquisition of inhibitory avoidance and escape expression of rats submitted to the elevated T-maze test of anxiety. Here, we investigated whether facilitation of 5-HT-mediated neurotransmission in the dorsal periaqueductal gray (dPAG) accounts for the behavioral consequences in the elevated T-maze induced by chemical stimulation of the LHb. The dPAG in the midbrain, which is innervated by 5-HT fibers originating from the dorsal raphe nucleus (DRN), has been consistently implicated in the genesis/regulation of anxiety- and fear-related defensive responses. The results showed that intra-dPAG injection of WAY-100635 or ketanserin, 5-HT 1A and 5-HT 2A/2C receptor antagonists, respectively, counteracted the anti-escape effect caused by bilateral intra-LHb injection of kainic acid (60 pmol/0.2 μl). Ketanserin, but not WAY-100635, blocked kainic acid's facilitatory effect on inhibitory avoidance acquisition. Overall, the results suggest that the pathway connecting the LHb to the DRN is involved in the control of 5-HT release in the dPAG, and facilitation of 5-HT-mediated neurotransmission in the latter area distinctively impacts upon the expression of anxiety- and fear-related defensive behaviors. While stimulation of 5-HT 1A receptors selectively affects escape performance, 5-HT 2A/2C receptors modulate both inhibitory avoidance and escape.
ISSN:0304-3940
1872-7972
DOI:10.1016/j.neulet.2010.05.021