Effects of Short-term Fasting on Selected Physiological Functions in Adult Male and Female Japanese Quail

Abstract

Lamo‰ova D ., M . M aaajova, M . Z eman: Effects of Short-term Fasting on Selected Physiological Functions in Adult Male and Female Japanese Quail. Acta Vet. Brno 2004, 73: 9-16. Effects of a short‐term fasting (0, 12, 24 and 48 h) on plasma leptin and alkaline phosphatase concentrations, selected parameters of lipid metabolism, protein and glucose were studied in both sexes of adult Japanese quail. Fasting caused a reduction of glucose concentration in liver of females (P < 0.05) and males (P < 0.05 - 0.001) as well as reduction of total lipids in plasma of females (P < 0.05 - 0.001) and liver of females ( P < 0.05) and males (P < 0.05‐0.01). Triacylglycerols decreased in plasma of females ( P < 0.05 and 0.01) and in liver of females ( P < 0.05 and 0.001) and males (P < 0.05 and 0.01). Significant effect of sex was proved by a decrease of liver weight (P < 0.05 - 0.01), total lipid concentration in plasma ( P < 0.05 and 0.001) and in liver (P < 0.05). Significant differences between sexes were also observed in concentration of triacylglycerols in plasma and liver ( P < 0.01 - 0.001). The sex differences were found also in the activity of alkaline phosphatase in plasma ( P < 0.05 - 0.001). Whereas no changes were found in males, in females the activity of alkaline phosphatase increased significantly after all fasting period (P < 0.05 - 0.001). Plasma leptin concentrations, egg laying, testes weight and protein content in plasma, liver and breast muscle were not affected by short-term starvation. We can conclude that short-term fasting affected mainly the lipid metabolism of adult birds. Sex differences, alkaline phosphatase, glucose, leptin, lipids metabolism, protein Food intake is influenced by genetic background and the endocrine status of the organism and, in turn, food intake can influence most of its physiological functions. It is known that deprivation of energy supply induces a delay in the development of some vital functions in mammals: puberty starts later, the reproductive age prolonges, ageing starts later and deterioration of immunity and health is delayed ( Banks and L ebel 2002). Changes in these vital functions are induced and accompanied by endocrine changes. Most information about these adaptive mechanisms is derived from studies in mammals ( Saudek and F elig 1976; Goodman and Ruderman 1980). In birds, it has been found that their response to prolonged fasting can be divided into three phases. The first phase, which lasts a few days, is characterized by a rapid decrease in body weight and high fat mobilization. The second phase is longer and characterized by a slow and steady decline in the rate of body weight loss and the third phase is a critical period characterized by an abrupt increase in the rate of body loss and increased protein catabolism (S artori et al. 1995). We focused on the first phase of fasting and analyzed the response of adult males and females of Japanese quail that have different fat stores. Present research of starvation in vertebrates is connected with studying of leptin that serves as a mediator of the adaptation to fasting. In humans, serum leptin concentrations as well as plasma levels of metabolic parameters (glucose, cholesterol, lipids) change rapidly