Localization of 5-ht(5A) receptor-like immunoreactivity in the rat brain

5-Hydroxytryptamine exerts modulatory physiological effects on both the cen tral and peripheral nervous systems by activation of discrete receptor fami lies. 5-ht(5A) is among the recently cloned, novel 5-HT receptors and curre ntly under investigation to identify its pharmacological characteristics an d potential physiological function(s). In this study, antibodies raised to a 5-ht(5A)-specific peptide were characterized using dot blot, sodium dodec yl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunohistoch emistry, and the distribution of 5-ht(5A)-like immunoreactive material dete rmined in rat brain. A major band of 41 kDa was observed following SDS-PAGE , corresponding to the predicted size of this receptor. 5-ht(5A)-like immun oreactivity was detected in areas known to have significant serotonergic in put, such as hypothalamic and amygdaloid nuclei. Interestingly, 5-ht(5A)-li ke immunoreactivity showed a predilection for the suprachiasmatic nucleus, suggesting its possible role in the regulation of circadian rhythms, a func tion previously ascribed to 5-HT1A and 5-HT7 receptors. (C) 2000 Elsevier S cience B.V. All rights reserved.