Distribution and cellular localization of mRNA coding for 5-HT1A receptor in the rat brain: correlation with receptor binding

Abstract

In order to localize the cells expressing SHT,, receptors in the rat brain, we used in situ hybridization histochemistry to visualize the distribution of the mRNA coding for SHT,, receptors. Oligonucleotides derived from different parts of the coding region of the rat 5-HT,, receptor gene were used as hybridization probes. 5-HT,, binding sites were visualized on consecutive sections by receptor autoradiography using 3H-8-hydroxy-2-(di-rpropylamino)tetralin as ligand. The highest levels of hybridization were observed in the dorsal raphe nucleus, septum, hippocampus, entorhinal cortex, and interpeduncular nucleus. Positive hybridization signals were also present in other areas, such as the olfactory bulb; cerebral cortex; some thalamic and hypothalamic nuclei; several nuclei of the brainstem, including all the remaining raphe nuclei, nucleus of the solitary tract, and nucleus of the spinal tract of the trigeminus; and the dorsal horn of the spinal cord.The distribution and abundance of SHT,, receptor mRNA in different rat brain areas generally correlate with those of the binding sites, suggesting that 5-HT,, receptors are predominantly somatodendritic receptors.Several different types of S-HT receptors have been pharmacologically defined (Peroutka, 1990). The recent molecular cloning ofthe genes or the cDNAs for four ofthese receptors, 5-HT,,, 5-HT,,, 5-HT,,, and 5-HT, (see Hartig, 1989, for a review; Branchek et al., 199 l), has suggested that they all belong to the monomeric G-protein-coupled receptor family (Dohlman et al., 1987). The distribution of 5-HT,, receptors has been examined in the rat brain by means ofreceptor autoradiographic technique (Marcinkiewicz et al., 1984;Pazos and Palacios, 1985) using a selective tritium-labeled ligand, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (Arvidsson et al., 198 1;Gozlan et al., 1983). Recently, 5-HT,, receptors have been also visualized by immunoautoradiography (El Mestikawy et al., 1990), using an antibody against a synthetic peptide derived from the predicted sequence of the rat 5-HT,, receptor. The light microscopic autoradiographic techniques used until now did not allow the unequivocal establishment of the cellular localization of receptors, which could only be inferred indirectly (Palacios and Dietl, 1988). A presynaptic localization of 5-HT,, receptors on the cell body and dendrites of serotoninergic cells, which would be responsible for the autoinhibition of 5-HT cells in the dorsal raphe (Wang and Aghajanian, 1977) is supported by biochemical (Hjorth et al., 1982), lesion (Weissman-Nanopoulos et al., 1985;Verge et al., 1986) and electrophysiological (Aghajanian et al., 1988) experiments. The cellular localization of 5-HT,, receptors in the projection areas of the raphe nuclei is less clear (Palacios and Dietl, 1988). However, in the hippocampus, lesion experiments suggested a localization of the receptors to neurons intrinsic to this region (Hall et al., 1985) and electrophysiological experiments pointed in particular to the hippocampal pyramidal c...

Distinguishing characteristics of serotonin and non-serotonin-containing cells in the dorsal raphe nucleus: electrophysiological and immunohistochemical studies

“…Furthermore, this antibody labeled appropriate bands on the Western blot predictive of the native 5-HT 1A receptor protein in both its unmodified and glycosylated forms. The distribution of immunohistochemical labeling for the receptor mapped to similar brain regions identified in other autoradiography (Kung et al, 1995), in situ hybridization (Pompeiano et al, 1992;Wright et al, 1995) and immunohistochemical studies using other 5-HT 1A receptor antibodies (Azmitia et al, 1996). For example, in the septum, other 5-HT 1A antibodies have shown similar labeling patterns: dense staining in the neuropil of the lateral septum and lighter labeling of soma in the medial septum (Kia et al, 1996;Zhou et al, 1999).…”

“…For example, in the septum, other 5-HT 1A antibodies have shown similar labeling patterns: dense staining in the neuropil of the lateral septum and lighter labeling of soma in the medial septum (Kia et al, 1996;Zhou et al, 1999). The heavy labeling in supraoptic nucleus and medial habenula was also demonstrated by another 5-HT 1A receptor antibody (Pompeiano et al, 1992;Kia et al, 1996).…”

“…9) to the pattern described in receptor binding autoradiography (Kung et al, 1995), in situ hybridization (Pompeiano et al, 1992;Wright et al, 1995) and immunohistochemistry studies using other 5-HT 1A receptor antibodies (Azmitia et al, 1996;Kia et al, 1996;Zhou et al, 1999). For these single-labeling studies, tissue was prepared as described above for dual immunohistochemistry.…”

“…For example, in the septum, other 5-HT 1A antibodies have shown similar labeling patterns: dense staining in the neuropil of the lateral septum and lighter labeling of soma in the medial septum (Kia et al, 1996;Zhou et al, 1999). The heavy labeling in supraoptic nucleus and medial habenula was also demonstrated by another 5-HT 1A receptor antibody (Pompeiano et al, 1992;Kia et al, 1996).For three antibodies generated against overlapping portions of the highly selective third intracellular loop of the 5-HT 1A receptor protein, there were slightly different subcellular labeling patterns. Kia et al (1996) used an antibody generated against a synthetic peptide corresponding to amino acid residues 243-268 and demonstrated labeling of soma as well as dendrites.…”

Knockout Mice Reveal Opposite Roles for Serotonin 1A and 1B Receptors in Prepulse Inhibition

“…Thus, assessment of the effects of flesinoxan on PPI in humans might soon be possible. Because 5-HT 1A receptors have a similar distribution pattern in the mouse (Ramboz et al 1998), the rat (Marcinkiewicz et al 1984;Pompeiano et al 1992), and humans (Pazos et al 1987;Hoyer et al 1986), unique distribution patterns are an unlikely reason for the species-specific effects of 8-OH-DPAT on PPI. A more plausible explanation is a difference in the balance of preand postsynaptic receptor signaling between species.…”