Adaptive changes of serotonin 5-HT2A receptors in mice lacking the serotonin transporter

The serotonin transporter (5-HTT) plays a key-role in the control of seroto ninergic neurotransmission and is the target of some antidepressants. Possi ble adaptive changes in brain 5-HT2A receptors were investigated in knock-o ut mice that do not express the 5-HTT. Autoradiographic labeling of these r eceptors by the selective antagonist [H-3]MDL 100,907 and saturation experi ments with cortical membranes revealed: (1) a new localization of these rec eptors in the external field of striatum (possibly in striosomes); (2) regi onal variations in adaptive changes in the density of 5-HT2A receptors in 5 -HT-/- mutants (-30-40% in the claustrum, cerebral cortex and lateral stria tum; no significant change in the striatum core) as compared to wild-type m ice. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.