The influence of thyroid state on hypothalamic AMP-activated protein kinase pathways in broilers

Area of Science:

• Animal Physiology
• Endocrinology
• Metabolic Regulation

Background:

• Thyroid hormones are crucial for regulating metabolism and energy balance.
• AMP-activated protein kinase (AMPK) is a key regulator of cellular energy homeostasis.
• The interplay between thyroid hormones and central AMPK signaling in energy regulation is not fully understood.

Purpose of the Study:

• To investigate the interaction between thyroid hormones and hypothalamic AMPK signaling in broilers.
• To determine how induced hyperthyroid and hypothyroid states affect AMPK-related gene and protein expression.
• To explore the role of AMPK pathways in mediating thyroid hormone effects on appetite and energy expenditure.

Main Methods:

• Broiler chicks were subjected to hyperthyroid (T3 supplementation) or hypothyroid (MMI supplementation) conditions for 7 days.
• Hypothalamic and systemic AMPK-related gene and protein expression were quantified.
• Alpha-lipoic acid (α-LA) was used to assess AMPK pathway modulation.
• Feed intake and body weight were monitored.

Main Results:

• Both hyperthyroid and hypothyroid states reduced feed intake and body weight.
• Hyperthyroidism increased AMPKα1 subunit expression, while hypothyroidism decreased phosphorylated AMPK but increased AMPKα1 and α2 gene expression.
• Evidence suggests AMPK pathways modulate the regulation of fatty acid metabolism genes (FAS, ACC) and anorexigenic neuropeptides (CRH, TRH, CNR1) in response to thyroid state.

Conclusions:

• Hypothalamic AMPK and related genes are involved in thyroid hormone-induced appetite changes in broilers.
• The specific involvement differs between hypothyroid and hyperthyroid states.
• These findings highlight a complex interaction between thyroid hormones and central AMPK signaling in energy homeostasis regulation.