No abstract

Heart rate variability in awake kittens under resting conditions was studied during the following periods of postnatal ontogeny: newborn animals, 10-day-old animals (eye opening), 20-day-old animals (rise on the legs), and 30-day-old animals (control). Newborn animals were characterized by high activity of the sympathoadrenal system due to birth stress. The effect of stress factors increased in 10-day-old kittens, which was related to the start of functioning of distant receptors and delivery of new environmental information into the brain. The acquisition of upright posture and locomotion on the limbs were accompanied by activation of the vagus nerve in kittens. Significant changes in temporal, geometric, and spectral characteristics illustrate an increase in adaptability of the organism and possibility for independent living (particularly, by the 30th day of life).

We analyzed the physical development indicators of two groups of children aged 6 and 12 months who were born prematurely and had different dynamics of blood levels of insulin-like growth factor-1 (IGF-1) in the neonatal period. At the age of 6 and 12 months, deviations in height or body weight from the reference values were more often observed in children who had a relatively low level of the hormone in the early neonatal period, followed by its increase in comparison with children who had the opposite dynamics of the hormone. In this group, a close relationship between somatometric indicators of infants and the blood content of IGF-1, albumin and glucose in newborns was revealed, which indicates a long-term persistence of the features of the nutritional status of the neonatal period and its influence on the subsequent physical development of these children.