D-aspartate stimulates growth hormone secretion in wethers

Area of Science:

• Animal Science
• Endocrinology
• Biochemistry

Background:

• Growth hormone (GH) is crucial for animal productivity.
• L-Aspartate (L-Asp) stimulates GH secretion in ruminants.
• The effect of D-aspartate (D-Asp) on GH secretion is unknown.

Purpose of the Study:

• To investigate the effect of D-Asp on GH secretion in wethers.
• To evaluate the impact of D-Asp on insulin, adrenaline, noradrenaline, NEFA, and glucose levels.
• To determine if D-Asp directly affects GH secretion from pituitary tissue.

Main Methods:

• Intravenous infusion of high-dose (0.1 mmol/kg/min) and low-dose (0.05 mmol/kg/min) D-Asp in wethers.
• Measurement of blood GH, insulin, adrenaline, noradrenaline, NEFA, and glucose concentrations.
• In vitro study of D-Asp's effect on GH secretion from cultured wether pituitary tissue.

Main Results:

• High-dose D-Asp infusion significantly increased blood GH concentrations and AUC.
• Low-dose D-Asp infusion also increased plasma GH concentrations and AUC.
• D-Asp infusion reduced plasma insulin concentrations and increased NEFA levels; adrenaline, noradrenaline, and glucose showed no significant changes.
• D-Asp showed a non-significant stimulatory effect on GH secretion in cultured pituitary tissue.

Conclusions:

• D-Asp stimulates GH secretion in wethers.
• The stimulation of GH secretion by D-Asp involves both direct pituitary action and other indirect pathways.
• D-Asp influences metabolic parameters like insulin and NEFA, suggesting broader physiological effects.