Dopamine and interscapular fat hemorrhage in the rat pup

Abstract

Female Sprague-Dawley rats were given dopamine during gestation. Several hours after birth, interscapular adipose tissue hemorrhages appeared in some of the offspring of dopamine-treated rats. Dopamine (10 mg/kg/day ip) administered during Days 1–7, 8–14, and 15–21 of gestation caused hemorrhages in 14.8, 6.2, and 0.0% of the offspring, respectively. Only 1.9 and 1.6% of 21-day fetuses from rats given either dopamine (10 mg/kg/day ip) or saline, respectively, during Days 1–7 of gestation had hemorrhages in the interscapular fat. During Days 1–7 of gestation, dopamine (10 mg/kg/day) given intramuscularly produced hemorrhages in only 3.0% of the offspring; intraperitoneal administration led to 14.8% hemorrhage. Female rats were given a single dose of 2.0 μCi of [ 14C]dopamine (10 mg/kg ip) on Day 7 of gestation and sacrificed after birth. No radioactivity was detected in the interscapular fat, liver, kidney, or brain of the newborn pups. Only the maternal adrenal gland and kidney contained measurable radioactivity (0.011 and 0.006% of the dose per gram of tissue). Moreover, rats given 0.5 μCi of [ 14C]dopamine (10 mg/kg im) on Day 3 of gestation excreted 99.9% of the radioactivity in their urine within 4 days. Neither vaginal norepinephrine content nor adrenal tyrosine hydroxylase activity in 21-day pregnant rats was altered by dopamine treatment during Days 1–7 of gestation. Thus, neither exogenous dopamine nor endogenous catecholamines appear to be the final mediator of the hemorrhagic mechanism.