Circulating somatomedin activity during hepatic regeneration.

Area of Science:

• Hepatology
• Endocrinology
• Growth Factor Regulation

Background:

• Liver disease and partial hepatectomy reduce circulating somatomedin activity.
• Nutritional changes can confound assessments of somatomedin activity following liver resection.

Purpose of the Study:

• To investigate the impact of partial hepatectomy on somatomedin activity, independent of nutritional status.
• To elucidate the role of the regenerating liver in somatomedin regulation.

Main Methods:

• Partial hepatectomy was performed on rats, with subsequent controlled nutrition and ad libitum feeding phases.
• Somatomedin activity was measured using a bioassay with cartilage from hypophysectomized rats.
• Nutritional effects were controlled by providing equicaloric restricted diets to both hepatectomized and sham-operated groups.

Main Results:

• Partial hepatectomy initially decreased somatomedin activity, which normalized within 6 days.
• Controlled nutrition revealed higher somatomedin activity in partially hepatectomized rats compared to sham-operated controls.
• Liver regeneration was impaired in hypophysectomized rats, with sustained low somatomedin activity.

Conclusions:

• The regenerating liver contributes to increased somatomedin activity when nutritional intake is controlled.
• The liver may enhance somatomedin production or reduce somatomedin inhibitors during regeneration.
• Pituitary factors are potentially crucial for the liver's regenerative response.