Endocrine Abstracts

Introduction: Among the adipokines, leptin is one of the hormones directly connects to body fat and obesity. Investigating the impacts of dietary amino acids on adipose tissue metabolism have emerged as a fascinating area for researchers which they reported that dietary amino acids can affect and regulate gene activity in adipose tissues both directly and indirectly, with positive or negative effects.

Methods: Visceral and subcutaneous adipose tissues were gathered from 98 non-diabetic participants aged ≥20, who had undergone elective abdominal surgery. Average intakes of AAAs including phenylalanine, tyrosine, and tryptophan were collected using a valid and reliable food frequency questionnaire. The leptin gene expression in visceral and subcutaneous adipose tissues was measured by Real-Time PCR.

Results: Mean (S.D.) age and AAA intake of participants (23% male) were 41.7 (14.2) years and 7.38 (3.7) g/day, respectively. Total AAA intakes in ranking order were phenylalanine 3.9 g (the highest), followed by tyrosine 2.3 g, tryptophan 3.3 g, corresponding to 3.7%, 2.1%, and 2.9% of total protein intakes, respectively. No significant difference was observed for leptin gene expression in subcutaneous (−0.135 vs 0.791, P=0.992) and visceral (−1.582 vs 0.915, P=0.891) fat mass between non-obese (BMI < 30 kg/m²) and obese (BMI ≥30 kg/m²) participants, respectively. After controlling for BMI and energy, dietary intake of dietary AAA (β=0.404, P<0.001), phenylalanine (β=0.522, P<0.001), tyrosine (β=0.224, P=0.081), and tryptophan (β=0.520, P<0.001) was positively associated with subcutaneous adipose tissues leptin gene expression among obese participants. Besides, a significant positive association of dietary AAA (β=0.513, P<0.001), phenylalanine (β=0.399, P<0.001), tyrosine (β=0.234, P=0.078), and tryptophan (β=0.430, P=0.001) with leptin mRNA from visceral adipose tissue were observed. Among non-obese participants, none of the AAA showed significant association with leptin gene expression in both adipose tissues.

Conclusion: Habitual intake of phenylalanine, tyrosine, and tryptophan were associated with leptin gene expression in visceral and subcutaneous adipose tissues, suggesting an important role of quality proteins intake in adipose tissue to regulate leptin expression.