بيان ژن آديپونكتين و گيرنده 2 آن (AdipoR2) در مجراي توليدمثلي بره‌هاي نر افشاري پيش از بلوغ

Gene Expression of Adiponectin and Its Receptor2 (AdipoR2) in Reproductive Tract of Growing Prepubertal Afshari Male Lambs

آدیپونكتین هورمونی است كه عمدتا از بافت چربی ترشح می‌شود و شواهد اخیر حاكی از نقش آن در تنظیم سیستم تولیدمثلی پستانداران است. هدف از این پژوهش بررسی پروفیل بیان ژن آدیپونكتین و گیرنده 2 آن (AdipoR2) در نواحی مختلف مجرای تولیدمثلی بره‌های نر نژاد افشاری در دوره‌ پیش از بلوغ بود. بدین منظور، 20 رأس بره نر نابالغ نژاد افشاری به چهار گروه سنی مختلف شامل؛ گروه‌های سنی 1 تا 2، 2 تا 3، 3 تا 4 و 4 تا 5 ماه اختصاص یافتند، سپس دام‌ها به روش جراحی اخته شدند و از چهار بافت سر، بدنه، دم اپیدیدیم و پارانشیم بیضه هر دام نمونه‌برداری به عمل آمد. بیان دو ژن آدیپونكتین و AdipoR2 با استفاده از تكنیك Real Time-QPCR در هر نمونه بافت بررسی شد. بطور خلاصه، بیان مداوم ژن‌های آدیپونكتین و AdipoR2 در تمام مراحل رشد، قبل و هنگام بلوغ مشاهده شد. اگرچه میزان بیان آدیپونكتین و AdipoR2 در بین گروه‌های سنی مختلف به لحاظ آماری متفاوت بود، با این حال تفاوت آماری معنی‌داری در مقدار بیان آن‌ها در بین چهار بافت مختلف پارانشیم بیضه و سر، بدنه و دم اپیدیدیم بره‌های نر نابالغ مشاهده نشد. نتایج بررسی حاضر نشان داد كه آدیپونكتین و گیرنده 2 آن (AdipoR2) به طور مداوم در مجرای تولیدمثلی بره‌های نر نابالغ بیان می‌شوند و سطح بیان آنها با افزایش سن تغییر می‌كند. با توجه به تازگی این موضوع، نتایج این مطالعه می‌تواند زمینه ساز مطالعات بیشتر در این زمینه مهم باشد. واژه های كلیدی: قوچ افشاری، بیضه، تولیدمثل، آدیپونكتین

Introduction Adiponectin, a novel adipocytokine mainly produced from adipocytes, acts through binding to its two functional receptors, AdipoR1 and AdipoR2. Some evidence has already suggested that adiponectin can be involved in the regulation of male reproductive functions. Our purpose was to detect of adiponectin and AdipoR2 mRNA transcripts in the reproductive tissues of growing pre-pubertal male lambs as well as adult rams. Materials and Methods At first, Afshari prepubertal male lambs (n=20), with no apparent abnormalities, were allocated to four different age groups (n=5/age group) including; 1-2 (Group 1), 2-3 (Group 2), 3-4 (Group 3), and 4-5 (Group 4) months of age, afterward were surgically castrated. At a local slaughterhouse, reproductive tissues from five adult Afshari rams (3-4 years-old), with no evident abnormalities, were also collected within 20 minutes after the rams were slaughtered. Both fresh whole testes for lambs and those for adult rams were instantly transported to the laboratory on ice and were frozen in the liquid nitrogen and stored at −80°C until analysis. Total RNA extracted from each tissue sample, converted to cDNA and finally, the relative expression levels of adiponectin and AdipoR2 transcripts were assessed by Quantitative Real time-PCR. Comparative ΔΔCt method was used for quantification of Real-Time PCR outputs. By GenEx enterprise software, obtained fold changes were statistically analyzed. Results and Discussion By real-time PCR, local gene expression of adiponectin and AdipoR2 was demonstrated in testis parenchyma and three different parts of epididymis (caput, corpus and cauda) for both immature male lambs and adult rams. The results showed that adiponectin and AdipoR2 levels persistently changed during pre-pubertal and pubertal developmental stages. There were no significant differences in adiponectin, and AdipoR2 mRNA levels among various tissues (p >0.05); but, mRNA quantities significantly varied among different age groups (p <0.05). A high positive correlation (r=0.72) was observed between ligand and AdipoR2. Because of developmental changes in adiponectin and AdipoR2 mRNAs levels among different age groups, expression levels appear to be under regulation of developmental cues and hormonal factors such as gonadotropins. It has already been demonstrated that AdipoR2, but not adiponectin, levels noticeably enhances by hCG (the superagonists of LH). Similar expression profiles of Adiponectin and AdipoR2, with increased expressions exactly before puberty to sexually mature animals, suggest that adiponectin may be involved to the expansion of the adult-type leydig cell population that takes place along the puberty transition. Since, Adiponectin affects glucose transporters (SLC2A1 and SLC2A3) expression in seminiferous tubular cells, and plays a major role in several metabolic functions such as glucose utilization, energy homeostasis and immunity; we speculated that adiponectin, locally expressed by testicular and epithelial cells, might be key regulator of various functions of reproductive cells. Conclusion The results of current study showed that adiponectin, locally expressed by testes and epididymis of prepubertal male lambs, can be engaged in onset of pubertal processes and affect male fertility as well. In summary, our study is the first to describe the local expression of adiponectin and its functional receptor2 (AdipoR2) transcripts in the genital tract of immature/growing ruminants. We also suggest that the AdipoR2 is probably a more important receptor for adiponectin.