Investigation on the Histopathological Effects of Thyroidectomy on the Seminiferous Tubules of Immature and Adult Rats

Abstract

Introduction: This study aimed to investigate the histopathological effects of thyroidectomy on both immature and adult rat testes. Materials and Methods: Male albino Wistar rats, 4 weeks old and weighing between 45 and 55 g, were used for this study. The experimental groups were as follows: 2-week control group (group I); 2-week thyroidectomy group (group II); 4-week control group (group III); 4-week thyroidectomy group (group IV); 6-week control group (group V), and 6-week thyroidectomy group (group VI). The control groups included both sham-operated and untreated rats. In groups II, IV and VI, total thyroidectomy was performed under ether anesthesia in all rats at 4 weeks of age. The rats were killed in the 2nd, 4th and 6th weeks, respectively, following the thyroidectomy. The testes of each animal were evaluated histologically. Results: In group II, spermatogenesis progressed to meiosis but round spermatids were found to be decreased and pachytene spermatocytes were observed to be increased when compared to group I. Giant pachytene spermatocytes were seen. There were also many degenerated cells of intermediate origin in the seminiferous epithelium. In groups IV and VI, spermatogonia and primary spermatocytes were normal in appearance, but there was widespread degeneration of the other spermatogenic cells. In addition, some closed lumina covered by degenerated and dead cells were observed. In group II, the mean outer diameter, luminal diameter and area occupied by seminiferous epithelium decreased by 19.74, 32.18, and 28.12%, respectively. In group IV, these data decreased by 23.9, 16.52, and 48.5%, respectively, and in group VI, by 21.10, 19.76 and 40.29%, respectively, when compared with the control groups. These data were statistically significant (p < 0.001). Conclusions: Thyroid hormones could have a marked influence on the seminiferous tubules of both immature and adult rats, and their permanent lack results in a depression in seminiferous tubule growth as shown by the reduced outer and luminal diameters and area occupied by the seminiferous epithelium, which could give rise to degenerative changes in the spermatogenic cells of thyroidectomized rats. In addition, all these changes could also result from both the inability of Sertoli cells to support spermatogenic cells and the diminished levels of GH and FSH.

The role of thyroid hormone in testicular development and function

“…Similar histological changes were observed in testis of adult rats subjected to chronic thyroid hormone deficiency due to thyroidectomy performed early in life (Oncu et al , 2004). In addition to the histological changes, reduced serum gonadotropins and testosterone levels were observed in both the rat models.…”

Alkaline phosphatase activity in plasma and liver of rats submitted to chronic exposure to fluoride

“…The increased fluoride concentrations in the kidneys of the animals treated with 15 and 50 ppm were expected, since kidneys were responsible for the excretion of fluoride (Whitford, 1996). Fluoride at 50 ppm was also capable to reduce the weight of the kidneys when compared to the control group, which was consistent to the findings of other studies demonstrating a nephrotoxic effect of fluoride at high doses (Kobayashi et al, 2009;Strunecka et al, 2007), with an altered proteomic profile, hydropic degeneration in epithelial cells and vascular congestion (Kobayashi et al, 2009;Oncu et al, 2004). The hydropic degeneration can cause shrinkage of glomeruli (Oncu et al, 2004), thus leading to a decrease in the weight of the organ.…”

Is there a role for thyroid hormone on spermatogenesis?

“…Of note, the infertility described in the male rdw rat seems to be partially reversed by T4 treatment (Jiang et al, 2000;Umezu et al, 2004). Analogous histological changes were observed in the testes of adult rats subjected to chronic thyroid hormone deficiency due to thyroidectomy performed early in life (Oncu et al, 2004). In addition to the histological changes, reduced serum testosterone levels were observed in both the rat models.…”

“…For instance, TRa1 expression was very high in Sertoli cell nuclei during their proliferative phase, from postnatal days 0 to 15, and subsequently declined markedly with the cessation of proliferation, remaining very low in adulthood. Interestingly, around postnatal day 15, TRa1 was found to be expressed in spermatogenic germ cells, from intermediate spermatogonia to mid-cycle pachytene spermatocytes, and also in Sakai et al, 2004Oncu et al, 2004Maran and Aruldhas, 2002 residual bodies being phagocytosed by Sertoli cells. Functional TR isoforms were also identified in the interstitial compartment of the immature testis, although it was not clear, at that point, in which specific cell types they were expressed (Buzzard et al, 2000).…”