Yaqiong Ye; Honghua Chen; Hong Xiao; Xiaoshu Zhan; Canying Liu; Shengfeng Chen & Hui Zhang

The silky fowl is characterized by hyperpigmentation. Currently, however, the physiological mechanism of hyperpigmentation has not been fully disclosed. Additionally, peripheral melanocytes and central dopaminergic neurons produce melanin and neuromelanin by the same substrate – L-tyrosine, respectively, but the relationship between dopaminergic neurons and peripheral melanogenesis remains unclear. In the present study, different levels of dietary L-tyrosine are fed to different groups of the silky fowl. After 4 weeks, midbrain dopaminergic neurons and melanosomes of cutaneous melanocytes are identified and counted by paraffin section, tyrosine hydroxylase (TH) immunohistochemistry and transmission electron microscopy, respectively. Within 0-0.8 % concentration range, L-tyrosine enhances the number of dopaminergic neurons and melanosomes (P<0.05). Moreover, the increased number of dopaminergic neurons and that of melanosomes is positively correlated (R2 = 0.6279). The results demonstrate that L-tyrosine promotes the increase of midbrain dopaminergic neurons and melanosomes of cutaneous melanocytes. L-tyrosine regulates positively cutaneous melanogenesis through dopaminergic neurons via the TH in silky fowl.

KEY WORDS: Chicken; Dopaminergic cell; Tyrosine hydroxylase; Melanosome.

YE, Y.; CHEN, H.; XIAO, H.; ZHAN, X.; LIU, C.; CHEN, S. & ZHANG, H. Effects of dietary L-tyrosine on dopaminergic neurons and cutaneous melanosomes in the silky fowl. Int. J. Morphol., 44(4):1141-1148, 2026.