There are two objectives of the ongoing research in my lab. Our first goal is to understand the process of follicle selection and development in the hen. The features of avian follicle development make the hen an ideal model for understanding the process of regulation of follicular recruitment. It is possible to study the production of a specific hormone by an individual follicle. We have studied the ovarian hormones inhibin, activin and anti-mullerian hormone as well as the oocyte-specific factor, GDF9. By understanding the interaction of the somatic cells and the oocyte in a species in which preovulatory development is so ordered and predictable, it may be possible to generalize these findings to other domestic animal species as well. A fundamental understanding of follicular recruitment is essential to maximizing reproductive efficiency, especially in turkeys and broiler breeder hens where egg production is not optimal. Our second research goal relates to the development and characterization of the chicken as a model for human ovarian cancer. There is no animal model, other than the hen, which spontaneously develops ovarian cancer with a high incidence. Previous studies, as well as our own data, show that hens develop ovarian cancer with a striking similarity to that found in human females. The main cause of the lethality of ovarian cancer in women is the fact that it is usually diagnosed at an advanced stage. The availability of an animal model will increase the chance of finding a marker for early diagnosis. In addition, an animal model will permit the testing of pharmaceuticals that may decrease the growth of this cancer. Finally, selected genomic analysis of hens with and without the disease may reveal a difference that underlies differential susceptibility to ovarian cancer.
Wojtusik, J. and P.A. Johnson. Vitamin D regulates anti-mullerian hormone expression in granulosa cells of the hen. Biology of Reproduction, doi:10.1095/biolreprod.111.094110
Correa, S.M., C. M. Horan, P. A. Johnson, E. Adkins-Regan. Copulatory behaviors and body condition predict post-mating female hormone concentrations, fertilization success, and primary sex ratios in Japanese quail. Hormones and Behavior, 59:556-564, 2011.
Trevino, L.S., J.R. Giles, W. Wang, M.E. Urick and P.A. Johnson. Gene expression profiling reveals differentially expressed genes in ovarian cancer of the hen: support for oviductal origin? Hormones and Cancer, 1:177-186, 2010.
Giles, J.R., R.G. Elkin, L.S. Trevino, M.E. Urick, R. Ramachandran and P.A. Johnson. The restricted ovulator chicken: A unique animal model for investigating the etiology of ovarian cancer. Int. J. Gynecol Cancer, 20:738-744, 2010.
Johnson, P.A., T.R. Kent, M.E. Urick, L.S. Trevino and J.R. Giles. Expression of anti-mullerian hormone in hens selected for different ovulation rates. Reproduction 137:857-863, 2009.
Urick, M.E., Giles, J.R. and P.A. Johnson. Dietary aspirin decreases the stage of ovarian cancer in the hen. Gynecol. Oncol, 112:166-170, 2009.
Urick, ME, Giles, JR and Johnson, PA. VEGF expression and the effect of NSAIDS on ascites cell proliferation in the hen model of ovarian cancer. Gynecological Oncology 110(3):418-424, 2008.
Johnson, PA, ME Urick, TR Kent and JR Giles. Expression and regulation of anti-mullerian hormone in the hen. Biology of Reproduction, 78:13-19, 2008.
Urick, M.E. and P.A. Johnson. Cyclooxygenase 1 and 2 mRNA and protein expression in the Gallus domesticus model of ovarian cancer. Gynecological Oncology, 103:673-678, 2006.