Breed differences in expression of inhibin/activin subunits in porcine anterior pituitary glands.

Endocrinology

PubMedID: 9003006

Li MD, Macdonald GJ, Ford JJ. Breed differences in expression of inhibin/activin subunits in porcine anterior pituitary glands. Endocrinology. 1997;138(2):712-8.
Chinese Meishan (MS) boars have greater plasma FSH concentrations than European White Composite boars, but this difference does not occur in females of these breeds. To understand this disparity, we studied expression of the follistatin gene and of genes for the inhibin/activin alpha-, beta A-, and beta B-subunits in porcine anterior pituitary glands using quantitative reverse transcription-PCR and ribonuclease protection techniques. We found that 1) the inhibin/activin beta A- and beta B-subunits and follistatin were expressed in porcine pituitary, 2) the alpha-subunit was not detected in the porcine pituitary, but was highly expressed in porcine follicles; and 3) the beta B-subunit gene is more abundantly expressed (2-fold greater) in MS boar pituitaries than in pituitaries of White Composite boars. We conclude that this is not due to a breed difference, because the expression levels of this gene were similar in pituitaries of females of these breeds. No breed differences were detected for other genes screened in this study. From these observations, we propose that activin B, a dimer of beta B-subunits and a stimulator of FSH secretion, may be partially responsible for the elevated plasma FSH concentrations in MS boars, and intrapituitary inhibin plays no or a very minimal role.