Expression of Luteinizing Hormone Receptor Isoforms in Mural Granulosa Cells Derived from Gir Cattle

LH receptor (LHR) isoforms can be a fine regulatory mechanism of its function. This study aimed to evaluate the LHR isoforms expression during follicular development in Gir cattle using Real Time PCR. Mural granulosa cells (GC) were recovered from nine heifers by ultrasound-guided aspiration of 4, 6, 8 and 10 mm follicles. Samples were centrifuged and cells washed and kept in RNA Later. The splicing of exon 10 (S10), splicing of exon 10 and adjacent partial splicing of exon 11 (S10+11), and partial splicing of exon 11 (S11) were evaluated. Total RNA was extracted and cDNA was synthesized using  commercial Kits. The beta-actin gene was used as endogenous control, and results were analyzed using REST software. Expression values are shown as mean±SEM. Expression data from 4 mm follicles were used as reference and its value was fixed as 1.00. All isoforms showed a decrease in the relative expression of 8 mm follicles (8.9±14.2; 10.6±17.1 and 0.01±0.02 for S10, S10+11 and S11, respectively), when compared to 6 mm follicles (31.2±52.3; 64.9±108.0 and 2.4±3.9) and 10 mm follicles (289.0±492.0; 51.5±91.1 and 56.9±96.3; respectively). Decreased expression of isoforms occurred during the expected moment of follicle deviation in Gir breed, when the transition from FSH to LH dependence takes place. Previous results of our group also demonstrated a peak in the LHR expression in 8 mm follicles GC. Altogether, these results suggest a possible role of isoforms in the fine regulation of LHR function during follicle deviation in cattle.

Financial support: Embrapa, CNPq, CAPES and Fapemig