Lipogenesis and Lipolysis in Fed and Fasted Chicks from High and Low Body Weight Lines

Abstract

Lipogenic and lipolytic capacities were examined in fasted and nonfasted 28-day-old chicks from high-weight (HW) and low-weight (LW) selected lines. Lipogenesis was assessed in liver and bone (sternum) tissues through the activities of malic enzyme (EC 1.1.1.40), citrate cleavage enzyme (EC 4.1.3.8), and acetyl coenzyme A carboxylase (EC 6.4.1.2), as well as through the in vitro incorporation of acetate-1-14C into liver and bone lipid fractions. Lipolysis was estimated through the in vitro release of free fatty acids (FFA) from abdominal adipose tissue and through plasma FFA. Fasting depressed lipogenesis and increased lipolysis. Regardless of the feeding state, LW chicks exhibited higher lipogenic and lipolytic capacities than their HW counterparts, suggesting that lipid degradation may be relatively more important than synthesis in determining net fat deposition. In addition, the incorporation of radioactive acetate into bone lipid was associated with detectable activity of lipogenic enzymes, providing further evidence that the skeleton is an important site of lipogenesis in the chicken.

Age-Related Changes in Tissue Metabolic Rates and Sensitivity to Insulin in the Chicken

“…It was demonstrated, for example, that a line of chickens selected for low body weight, characterized by reduced abdominal fat pad mass, had greater adipose tissue lipolytic and hepatic lipogenic capacities than a high body weight line (Calabotta et al, 1985). It was proposed that the increased lipolytic rates in the low weight birds prevented (Calabotta et al, 1985). Thus, it was proposed that the predominant mechanism controlling net adipose tissue deposition was lipolysis rather than lipogenesis.…”

“…This is likely related to counteracting rates of tissue degradation and energy utilization in conjunction with synthesis. It was demonstrated, for example, that a line of chickens selected for low body weight, characterized by reduced abdominal fat pad mass, had greater adipose tissue lipolytic and hepatic lipogenic capacities than a high body weight line (Calabotta et al, 1985). It was proposed that the increased lipolytic rates in the low weight birds prevented (Calabotta et al, 1985).…”

Thyroid Function in Embryonic and Early Posthatch Chickens and Quail

“…They also could be used to gain greater understanding of the role of TH in growth and development of birds, e.g., by the use of models such as the genetically selected high and low weight lines of chickens mentioned earlier. Chicks from these lines are different biochemically and metabolically in a number of ways, including their hepatic malic enzyme activity (Calabotta et al, 1985).…”

Glucagon-Stimulated Lipolysis of Primary Cultured Broiler Adipocytes

“…Obesity in poultry induced by genetic selection (Calabotta et al, 1983(Calabotta et al, , 1985 or by hypophysectomy (Gibson and Nalbandov, 1966;Chandrabose and Bensadoun, 1971) is attributed to a decrease in adipose tissue lipolysis rather than to an increase in liver lipogenesis. Therefore, under certain physiological conditions, lipolysis may be the predominant metabolic pathway influencing fat accretion in broilers.…”