PARENT SESSION
SLIDE SESSION 13: GONADAL FUNCTION
Chairs: Robert Burghart, Francisco Moran (Trainee)
Univ Ottawa-Monpetit 203
1:30 PM-3:30 PM

EFFECT OF THYROID HORMONE ON ANTI-MULLERIAN HORMONE EXPRESSION IN THE NEONATAL RAT TESTIS.

Mendis-Handagama, Charmi^1,2, Ariyaratne, HBS², Facteau, Kellie¹, Wang, H-CR¹, Mrkonjich, L.¹, ^{1 2}

ABSTRACT- EFFECT OF THYROID HORMONE ON ANTI-MULLERIAN HORMONE EXPRESSION IN THE NEONATAL RAT TESTIS. SMLC Mendis-Handagama^1,2, HBS. Ariyaratne^2*, KA Fecteau¹, H-CR Wang^1*, and L Mrkonjich.^1* Department of Comparative Medicine¹ and Animal Science², The University of Tennessee, Knoxville, TN 37996, U.S.A. Differentiation of adult Leydig cells (LC) in the neonatal rat testis is regulated positively by the thyroid hormone. Anti-Mullerian Hormone (AMH) produced by the immature Sertoli cells in the neonatal testis has been suggested to be a negative regulator of the above process. As thyroid hormone induces Sertoli cell maturation in the neonatal testis, it is possible that thyroid hormone stimulation of the Leydig cell differentiation is mediated via inhibition of AMH production by the Sertoli cells with their maturation. If this is true, AMH production by the neonatal Sertoli cells in hypothyroid rats should not decline immediately after birth as in euthyroid rats, but should be maintained throughout the hypothyroid period at a similar or higher level to that of day 1 rats. This concept was tested in the present study. Control rats (days 1, 7 and 14) and hypothyroid rats (fed 0.1% propyl thiouracil/PTU to lactating mothers, days 7 and 14) were used. Production of AMH in these testes was examined by performing immunocytochemistry and immunoblotting analysis for AMH. Results demonstrated that day 1 control testes have intense AMH positive labeling indicating high levels of AMH expression in contrast to testes at days 7 and 14 in both control and PTU rats, which barely showed positive labeling. Immunoblots revealed that AMH content in testis tissue (equal amounts of protein) was much greater at day 1 compared to days 7 and 14 in both control and hypothyroid rats. These findings suggest that AMH production of neonatal Sertoli cells is not regulated by thyroid hormone, and therefore, thyroid hormone regulation of Leydig cell differentiation in the neonatal rat testis could not possibly be mediated via Sertoli cell AMH.

KEY WORDS: AMH production, Sertoli cell maturation, Leydig cell differentiation