Semax attenuates the influence of neonatal maternal deprivation on the behavior of adolescent white rats

Maternal deprivation in the early postnatal period significantly affects the behavior and development of different animals. Here we studied delayed effects of daily maternal deprivation (5 h/day) on physical development and behavior of white rats during postnatal days 1 to 14. Here we studied the possibility of reducing the negative consequences of deprivation by daily intranasal treatment with Semax, an analog of ACTH(4-10), in a dose of 0.05 mg/kg from postnatal days 15 to 28. It was found that maternal deprivation decelerated the growth of young rats, boosted physical activity and emotional reactivity in novel environment, and increased anxiety in one-month-old animals. Semax weakened the impact of deprivation on animal body weight and normalized the levels of anxiety in rats.

Correction of Long-Lasting Negative Effects of Neonatal Isolation in White Rats Using Semax

Adverse experience during the early postnatal period induces negative alterations in physiological and neurobiological functions, resulting in long-term disorder in animal behavior. The aim of the present work was to study the long-lasting effects of chronic neonatal stress in white rats and to estimate the possibility of their correction using Semax, an analogue of ACTH fragment (4-10). Early neonatal isolation was used as a model of early-life stress. Rat pups were separated from their mothers and littermates for 5 h daily during postnatal days 1-14. The pups of the control group were left undisturbed with the dams. Half of the rats subjected to neonatal isolation received an intranasal injection of Semax at a dose of 50 g/kg daily, from postnatal day 15 until day 28. The other animals received intranasal vehicle injections daily at the same time points. It was shown that neonatal isolation leads to a delay in physical development, metabolic disturbances, and a decrease in the corticosterone stress response in white rats. These changes were observed during the first two months of life. Semax administration weakened the influence of neonatal isolation on the animals, body weight , reduced metabolic dysfunction, and led to an increase in stress-induced corticosterone release to the control values. So the chronic intranasal administration of Semax after termination of the neonatal isolation procedure diminishes the negative effects of neonatal stress.