Twenty-one- and 40-day-old offspring from female rats exposed to emotional stress for 3 weeks and mated with intact males 10 days later were examined. Intact female offspring served as the control. The weight of the brain of 21- and 40-day-old experimental rats varied is a wider range compared to the control. In 40-day-old experimental males, the mean weights of the brain and hemisphere were lower than in controls. In 21-day-old rats, layer V neuronal nuclei were enlarged, while the thickness of the parietal cortex tended to decrease. In 40-day-old animals, morphometric parameters of neurons in the neocortex and hippocampus and RNA concentration in their cytoplasm did not differ from the control. Thirty-day-old experimental rats demonstrated low exploratory activity in the plus-maze test.

Low neuronal density in the neocortex, low serotonin concentration in the brain stem and hemisphere, 2-fold reduced norepinephrine content in the brain stem, and behavioral disorders were found in 40-day-old offspring of female rats treated with lead on day 18 of pregnancy. Key Words: brain; offspring; leadLead affects functional state of the nervous system [1,2,11], especially in children (high lead concentration in bones is associated with asocial, aggressive, or even criminal behavior) [2,11 ]. The intelligence quotient correlates with dentinal lead content in schoolchildren. Lead crosses the placental barrier and is found in breast milk [ 11]. Therefore, studies of delayed lead effects on developing brain are of prime interest. MATERIALS AND METHODSThe offspring (n=19) of 3 rat dams receiving 200 mg/kg PbNO 3 (4% water solution through a gastric tube) on day 18 of pregnancy was examined. The offspring (n=36) of 4 intact rats served as the control. Dams and their offspring were kept in the same vivarium with ad libitum food and water supply. Total exploratory activity of 1-month-old animals was studied in an elevated plus-maze (EPM) [11]. The rats were placed to the center of EPM (5 min). Total locomotor activity was estimated by the time spent in open arms. number of hang down movements, total time spent in open and closed arms, and the number of arm entries. The active exploratory, displacement, and passive explorDepartment of Histology, Department of Normal Physiology, and Central Research Laboratory, Far-Eastern State Medical University; Khabarovsk Regional Center of Mental Health atory behavioral profiles were evaluated by the number of rearings, grooming reactions, and sniffins, respectively. Each parameter was expressed in percents of the control. Rats aging 40 days were decapitated, and the body weight and weight of the brain were measured. Paraffin sections (7 g width) from the left anterioparietal and parietal lobes stained with 1% methylene blue were examined, the width of the cortex and its molecular layer were determined, and the mean number of neurons in a standard vision field in layers I and V were calculated. In the right hemisphere the contents of epinephrine, norepinephrine, dopamine [4,9], histamine, and serotonin [ 12] were measured on a spectrofluorometer (Hitachi). RESULTSPrenatally treated rats had greater body weights compared to control animals, which was probably due to their lower number in litters (6-8 vs. 8-12 in the control, Table 1). The absolute weight of the brain and width of the cortex and its molecular layer in treated and control rats were similar, while the relative weight of the brain in treated rats was 18.4% lower than in the control. Neuronal densities in the cortical layer V of the anterioparietal and parietal lobes in treated rats were lower than in the control by 14 (0.05