Bovine gonadotrophs express anti-Mullerian hormone (AMH): comparison of AMH mRNA and protein expression levels between old Holsteins and young and old Japanese Black females

Anti-Mullerian hormone (AMH) is secreted from ovaries and stimulates gonadotrophin secretion from bovine gonadotroph cells. Other important hormones for endocrinological gonadotroph regulation (e.g. gonadotrophin-releasing hormone, inhibin and activin) have paracrine and autocrine roles. Therefore, in this study, AMH expression in bovine gonadotroph cells and the relationships between AMH expression in the bovine anterior pituitary (AP) and oestrous stage, age and breed were evaluated. AMH mRNA expression was detected in APs of postpubertal heifers (26 months old) by reverse transcription-polymerase chain reaction. Based on western blotting using an antibody to mature C-terminal AMH, AMH protein expression was detected in APs. Immunofluorescence microscopy utilising the same antibody indicated that AMH is expressed in gonadotrophs. The expression of AMH mRNA and protein in APs did not differ between oestrous phases (P>0.1). We compared expression levels between old Holsteins (79.2 +/- 10.3 months old) and young (25.9 +/- 0.6 months old) and old Japanese Black females (89.7 +/- 20.3 months old). The APs of old Holsteins exhibited lower AMH mRNA levels (P<0.05) but higher AMH protein levels than those of young Japanese Black females (P<0.05). In conclusion, bovine gonadotrophs express AMH and this AMH expression may be breed-dependent.