The role of insulin-like growth factor and leptin in the pathogenesis of internal non-contagious pathology of dairy cows

Abstract

The endocrine system plays a key role in the pathogenesis of the non-infectious pathology of dairy cows. However, the role of a number of hormones in pathology is not clear. These hormones include insulin-like growth factors and leptin. The insulin-like growth factor is synthesized predominantly in the liver in response to an increase in the level of somatotropic hormone in the blood. According to its physiological properties, it is close to insulin, structurally similar, has common receptors that trigger the same chain of reactions: stimulates transport of amino acids and glucose in the muscles, increases the sensitivity of cells to insulin, in adipose tissue, transport glucose, oxidation of glucose to carbon dioxide, the inclusion of glucose in lipids. Leptin is synthesized by adipocytes, and its main physiological function is to reduce the synthesis of macroergic compounds and increase energy expenditure. Circulating in the blood, it helps to maintain an optimal level of glucose, which is necessary for the energy needs of the body. The purpose of this study was to investigate the concentration of insulin-like growth factor, leptin, glucose, pyruvate and lactate in the blood of cows under secondary osteodystrophy, ketosis and hepatodistrophy. This will give an opportunity to better understand the pathogenesis and create theoretical preconditions for the development of informative diagnostic tests and effective means of treatment. The experiment was conducted on dairy cows, analogues by age, breed, productivity and physiological state. According to clinical features, urine analysis and values of biochemical parameters of blood of experimental cows were divided into four groups: 1 – clinically healthy cows, 2 – patients with osteodystrophy, 3 – patients with ketosis, 4 – patients with hepatodistrophy. The obtained results of research indicate that the internal non-contagious pathology in dairy cows deficiency of exchange energy is recorded, which induces an increase in the activity of gluconeogenesis and is expressed by lowering the concentration of glucose and increasing the content of pyruvate and lactate. At the same time, a decrease in the level of insulin-like growth factor and leptin was found. The lowest level of insulin-like growth factor and leptin was determined by ketosis. The decrease in the level of tissue hormones in the blood plasma of cows under osteodystrophy was within the statistical error.

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“…The tissue hormone leptin is synthesized by adipocytes, and its main physiological function is to reduce the synthesis of macroergic compounds and increase energy expenditure. Circulating in the blood, leptin helps support optimal glucose levels, which are essential for the body's energy needs (Petruh et al, 2018). The results of the conducted studies indicate (Fig.…”

“…Apart from insulin and cortisol, markers of metabolism in dairy cows can also be the concentration of insulin-like growth factor (IGF, somatomedin) and leptin in blood plasma (Petruh et al, 2018). Presently, IGF and leptin can be attributed to understudied hormones.…”

“…This suggests that a decrease in the synthesis of IGF and thyroid hormones is a consequence of the physiological regulatory features of this period. It is indicated that the level of IGF in the blood depends on the concentration of thyroid hormones that increase the secretion of IGF by the liver (Petruh et al, 2018). Starting from Days 10-14 after calving, compared to Days 2-4 days, the concentration of T3 in the blood plasma of cows increased by 2.1 times (4.7 ± 0.5 nmol/L; P < 0.001) and T4 -by 53% (79.9 ± 6.2 nmol/L; P < 0.01).…”