| Abstract: | Summary The effect of -methyl-p-tyrosine methylester hydrochloride (-MT) (100 mg/kg i.p.) orp-chlorophenylalanine methylester hydrochloride (PCPA) (150 mg/kg i.p.) on lordosis behaviour in estrogen pretreated spayed rats was investigated. The effect of-MT was studied 1, 2, 4, 8 and 26 hours after the drug injection and the observations after PCPA were done 2, 4, 8, 26 and 50 hours after the injection. Facilitation of lordosis was seen 2–8 hours after both treatments. Biochemical experiments were done in parallel and the injection of either-MT or PCPA resulted in a transient decrease in brain catecholamines which was correlated in time with the facilitation of the lordosis response. Furthermore PCPA resulted in a gradual decline in brain 5-HT. However, when 5-HT depletion was most pronounced and the brain catecholamines had returned to control levels no increase in lordosis behaviour occurred. Our findings suggest a role for central catecholamines in the mediation of lordosis behaviour in ovariectomized estrogen-drug-treated rats. |
