D Aït Amara | PubMed Health

PubMed2001

Region-specific decrease in 5-HT1A and 5-HT1B binding sites after intra-hippocampal ibotenic acid injections in the rat.

The cellular location of 5-HT1A and 5-HT1B binding sites in the hippocampus was investigated using a stereotaxic unilateral lesion of the CA1 field by ibotenic acid, followed by autoradiography on brain sections with the specific ligands [3H]8-OH-DPAT and S-CM-G[125I]TNH2, respectively. As compared to the contralateral side of the lesion, the ipsilateral side exhibited a decrease in the density of 5-HT1A binding sites in the strata oriens and radiatum of CA1, and of 5-HT1B binding sites in the dorsal subiculum and stratum oriens of CA1. The results demonstrate that 5-HT1A binding sites are located on dendrites whereas 5-HT1B binding sites are located on axon terminals of CA1 pyramidal cells.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1995

Serotonin 1B receptor regulation after dorsal subiculum deafferentation.

The subiculum may be the key structure in the transfer of relevant processed information from the hippocampal formation to cortical areas. We investigated the location of the serotonin 1B receptor (5-HT1B) in the hippocampus with the specific ligand serotonin-O-carboxymethyl-glycyl[125I]tyrosinamide in rat brain sections using in vitro autoradiography. A high density of 5-HT1B binding sites was found in the dorsal subiculum (DS), in the lacunosum moleculare, and in the most dorsal layer of the stratum oriens of the CA1 field. CA1 pyramidal neurons that contain 5-HT1B mRNA project primarily to the DS. We interrupted the pyramidal CA1 axons unilaterally by a stereotaxic knife cut. Histological analysis showed that the lesion was restricted to a trial of cells lost between CA1 and DS. Specific 5-HT1B binding site density was decreased in the DS on the ipsilateral side of the lesion compared to the contralateral side. We conclude that 5-HT1B receptors are located on CA1 pyramidal axon terminals in the DS. Serotonin, acting on these receptors, should inhibit CA1 neurotransmitter release and, in this way, modulate subicular functions.

Animals↗