Effect of Experimental Litter Reduction on Cerebellum Development in Suckling Rats.

We studied morphological features of the cerebellum in 14-day-old Wistar rats from reduced litters (the number of pups was reduced from 10-12 to 6 on the next day after birth). The control group comprised 14-day-old animals from litters of medium size (10-12 rat pups). Rats from reduced litters had greater body weight and brain weight.

Influence of Litter Reduction in the Neonatal Period at Different Times after Birth on the Parameters of Brain Development in Rats.

We studied the brain of 5- and 14-day-old intact (control group) rats and rats of the same age from litters experimentally reduced on days 1 and 5 after birth (experimental groups). In animals of both experimental subgroups, the brain had morphological signs of advanced development: greater weight of the brain and hemisphere, greater thickness of the cortex, its molecular layer, lower numerical density of neurons in the anterior parietal and proper parietal lobes, greater sizes of neurons, their nuclei, and nucleoli in the neocortex of these zones, and increased concentration of RNA in the cytoplasm of neurons. These data suggest that the rate of brain development in rats can be accelerated under the influence of environmental changes that occur after litter reduction during the neonatal period at different times after birth.

Effect of Experimental Litters Reduction during the Neonatal and Suckling? Periods of Ontogeny on Some Parameters of Brain Development in 30-Day-Old Rats.

We compared the effect of litter reduction on day 1 (series I) and day 14 after birth (series II) on the weight of the brain and right hemisphere and on the morphometric indicators of the development of the anteroparietal lobe in rats. Animals from both experimental series showed signs of acceleration (higher body weight and weights of the testes and ovaries). In series I, the weight of the brain and hemisphere and the thickness of the cortex surpassed the control values; the numerical density of neurons in layers II and V was lower and the numerical density of gliocytes was higher than in the control.

Dependence of Some Indicators of Brain Development in 30-Day-Old Rats on the Dynamics of Body Weight Gain in the Neonatal and Suckling Periods in Litters of Different Sizes.

We analyzed the dependence of the weight of the brain, its hemispheres, and morphometric parameters of the parietal cortex and the hippocampus in 30-day-old Wistar rats on their body weight at the age of 1, 7, 14, 21, and 30 days. All the animals were from medium-sized litters. In 6 litters (experiment), 6 rat pups were left in each litter 1 day after delivery; in 6 other litters (control), their number remained unchanged (8-13 pups).

Immediate and Delayed Effects of Food Restriction on Some Parameters of Brain Development in Rats.

The effects of 15-day restriction diet (from 1 to 1.5 months of age) on some parameters of brain development were studied in rats. The immediate and delayed (15 days after transfer to normal ration) effects were evaluated.