Positive Association between Expression of Follicle-Stimulating Hormone ß and Activin ß_B-Subunit Genes in Boars¹

^a Endocrine Research Laboratory, Minneapolis Medical Research Foundation and Departments of Medicine, Hennepin County Medical Center and University of Minnesota, Minneapolis, Minnesota 55404 ^b UMDNJ-Robert Wood Johnson Medical School, Department of Neuroscience&Cell Biology, Piscataway, New Jersey 08854 ^c USDA, ARS, RLH U.S. Meat Animal Research Center, Clay Center, Nebraska 68933

This study tested our hypothesis that inhibin/activin (I/A) ß_B subunit and not follistatin (FS) gene expression relates positively to plasma FSH concentrations in the anterior pituitary gland of boars. Mature crossbred boars (n = 12) were selected for divergence in plasma FSH concentrations, and their anterior pituitary glands were evaluated for expression of the FSHß, I/A ß_B, FS, calmodulin, and GnRH receptor (GnRH-R) genes by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and/or RNase protection assays (RPAs). Expression of I/A ß_B was greater (p < 0.01) in the six boars with high FSH than in the six with low FSH; expression of the I/A ß_B-subunit gene was positively correlated to that of the FSHß gene (RT-PCR: r = 0.96; p < 0.01; RPA: r = 0.68; p < 0.05). In contrast, expression of the FS (p > 0.10), GnRH-R (p > 0.08), and calmodulin (p > 0.10) genes was similar in the two groups of boars. Additionally, expression of the FSHß gene was correlated positively with pituitary and plasma FSH concentrations (r = 0.69 and 0.88, respectively; p < 0.05). These results support the hypothesis that activin B is partially responsible for elevated FSH concentrations in boars. Furthermore, the expression difference of the calmodulin gene observed previously between Meishan and White Composite boars represents a breed difference unrelated to FSH.

¹ Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the same by USDA implies no approval of the product to the exclusion of others that may also be suitable.

² Correspondence: J. Joe Ford, USDA, ARS, RLH U.S. Meat Animal Research Center, P.O. Box 166, State Spur 18D, Clay Center, NE 68933. FAX: 402 762 4382; ford{at}email.marc.usda.gov

³ Current address: Department of Pharmacology, University of Tennessee, Memphis, TN 38163.

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