[3H]-SB-269970 radiolabels 5-HT7 receptors in rodent, pig and primate brain tissues

The selective 5-HT7 receptor antagonist radioligand, [H-3]-SB-269970, has been reported to radiolabel the human cloned 5-HT7(a) receptor and 5-HT7 receptors in guinea pig cortex (Thomas et al.. 2000). Saturation analysis of [H-3]-SB-269970 binding to mouse forebrain. rat cortex. pig cortex, marmoset cortex and human thalamus membrane, was consistent with labelling a homogenous population of binding sites in each tissue. K-D values for [H-3]-SB-269970 binding in these tissues ranged from 0.9 to 2.3 nM, being similar to those reported for the human cloned and guinea pig cortex 5-HT7 receptors (1.3 and 1.7 nM, respectively). B-max values for [H-3]-SB-269970 binding to the Mouse. rat. pig. marmoset and human brain membranes were 20, 30. 31, 14 and 68 fmoles mg protein(-1). respectively. For each species the profile of inhibition of [H-3]-SB-269970 binding. using a number of 5-HT7 receptor agonists and antagonists. correlated well with that reported for the human cloned 5-HT7(a) receptor (correlation coefficients were 0.95. 0.94. 0.92. 0.95, 0.97 versus the mouse. rat. pig, marmoset and human tissues, respectively). In conclusion. [H-3[-SB-269970 has been shown to radiolabel 5-HT7 receptors in rodent. pig and primate brain and represents a valuable tool with which to further characterise the distribution and function of 5-HT7 receptors in native tissues and elucidate their potential role in disease states. (C), 2002 Elsevier Science Ltd. All rights reserved.