The role of 5-HT receptor subtypes in the ventrolateral orbital cortex of 5-HT-induced antinociception in the rat

C L Qu, F Q Huo, F S Huang, Y Q Li, J S Tang, H Jia
Neuroscience 2008 March 18, 152 (2): 487-94
The present study examined the involvement of 5-HT in the ventrolateral orbital cortex (VLO) on descending antinociception and determined which subtypes of 5-HT receptors mediated this effect. This study focused on the effects of 5-HT microinjection in the VLO of lightly anesthetized male rats on the radiant heat-evoked tail flick (TF) reflex, as well as the influence of 5-HT(1A), 5-HT(2), 5-HT(3), and 5-HT(4) receptor subtype antagonists on the effect of 5-HT. Results showed that 5-HT microinjection (2, 5, 10 microg, in 0.5 microl) into the VLO depressed the TF reflex in a dose-dependent manner. Pretreatment with 5-HT receptor antagonists (1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine hydrobromide (NAN-190), cyproheptadine hydrochloride (CPT) and 1-methyl-N-(8-methyl-8-azabicyclo[3.2.3]-oct-3-yl)-1H-indazole-3-carboxamide maleate salt (LY-278,584)), specific for 5-HT(1A), 5-HT(2) and 5-HT(3) receptors, respectively, partially reversed the 5-HT-evoked inhibition. In contrast, the 5-HT(4) receptor antagonist, 1-[2-[(methylsulfonyl)-amino]ethyl]-4-piperidinyl]methyl1-methyl-1H-indole-3-carboxylate (GR 113808), had no effect on the inhibition of 5-HT. Microinjections of NAN-190, CPT and LY-278,584 alone into the VLO had no effect on the TF reflex. These results suggest that 5-HT(1A), 5-HT(2) and 5-HT(3), but not 5-HT(4) receptors, are involved in mediating 5-HT-induced antinociception in the VLO. According to different properties and distribution patterns of the 5-HT receptor subtypes on neurons, the possible mechanism of 5-HT activation of the VLO-periaqueductal gray (PAG) descending antinociceptive pathway is discussed.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"