Apparent absence of serotonin_1B receptors in biopsied and post‐mortem human brain

Abstract

In order to determine if post-mortem delays could account for the apparent absence of 5-HT1B sites reported in human brain, 5-HT1B binding parameters were determined in fresh and fresh-frozen cortical biopsies and compared to results obtained in post-mortem tissues. Binding parameters and in vitro receptor autoradiography were performed by using two different ligands which have been shown to label 5-HT1B sites, namely [3H]5-HT, in presence of 100 nM 8-OH-DPAT, and [125I]cyanopindolol, in presence of 10 microM (-)isoproterenol. No specific binding was detected with [125I] cyanopindolol in either fresh cortical biopsies or post-mortem tissues, suggesting that the apparent absence of 5-HT1B receptor sites reported earlier was not related to long post-mortem delays. Some specific labelling was seen with [3H]5-HT, in presence of 8-OH-DPAT. This binding, which is unlikely to be to the 5-HT1B type, could represent labelling to the 5-HT1D or 5-HT1E sites.

Autoradiographic Analyses of the Effects of Adrenalectomy and Corticosterone on 5-HT_1A and 5-HT_1B Receptors in the Dorsal Hippocampus and Cortex of the Rat

“…The autoradiographic analysis of 5-HTm re ceptors was performed in the manner of Martial et al [9]. Brain sections were placed for 10 min in room temperature preincubation buffer consisting of 170 mM Tris-HCI (pH 7.4).…”

Binding studies with the 5‐HT1B receptor agonist [3H]CP‐96,501 in brain tissues

“…Several studies have reported that the 5-HTl, receptor subtype is found in the brain of mice and rats but not in guinea pigs and higher mammalian species, including humans [Heuring et al, 1986;Hoyer et al, 1986;Pazos et al, 1987;Martial et al, 1989;Waeber t:t al., 1989a). On the other hand, the analogous receptor subtype HIT,,, is present in the brain of guinea pigs, higher mammals, humans, and pigeons, with localization in areas corresponding to 5-HT,,-rich regions in the rat brain [Heuring and Peroutka, 1987;Waeber et al, 1988aWaeber et al, ,b, 1989aPeroutka et al, 19891.…”

Characterization of [3H]CP‐96,501 as a Selective Radioligand for the Serotonin 5‐HT1B Receptor: Binding Studies in Rat Brain Membranes

“…The 5-HTIB receptor subtype has been reported to be present only in the brain of mice and rats and absent in the brain of guinea pigs and higher mammalian species, including humans (Heuring et al, 1986;Hoyer et al, 1986;Pazos et al, 1987;Martial et al, 1989;Waeber et al, 1989). Its proposed localization in rat brain (Palacios and Dietl, 1988; Hamon et al, 1990) as postsynaptic receptors on cell bodies of intrinsic stnatal neurons and terminals of stnatal neurons projecting to the substantia nigra and globus pallidus and autoreceptors on 5-HT nerve terminals regulating release indicates important functional roles for the 5-HTIB receptor.…”