A PET STUDY OF D-2 DOPAMINE-RECEPTOR DENSITY AT DIFFERENT PHASES OF THE MENSTRUAL-CYCLE

Behavioral and biochemical studies in animals indicate that central do paminergic neurotransmission may be modulated by sex steroids. This ma y be the mechanism underlying the suggested association between estrog en and schizophrenia. The aim was to examine if different levels of se x steroids during the menstrual cycle are associated with variations i n D-2 dopamine receptor density as measured with positron emission tom ography (PET) and [C-11]raclopride. Five healthy women were examined, one during two subsequent follicular phases and four during two differ ent phases of their menstrual cycle. In none of the women did the diff erence in putamen to cerebellum (P/C) ratios (-11 to 10%) exceed the d ifference in P/C ratios previously reported in test-retest analyses in men(-11 to 9%). The findings do not support the conclusion that there is a menstrual-cycle-dependent variation in D-2 receptor density dete ctable with single PET examinations and [C-11]raclopride. Furthermore, a stable P/C ratio throughout the menstrual cycle indicated a stable D-2 receptor occupancy in schizophrenic women treated with antipsychot ic drugs. Repeated PET examinations of schizophrenic women known to de teriorate during particular phases of their menstrual cycle may furthe r contribute to our understanding of the association between schizophr enia and sex steroids. (C) 1998 Elsevier Science Ireland Ltd. All righ ts reserved.