histologic study of carbimazole-induced hyperplasia of adenohypophysis with protective role of thyroxine in male albino rats

ABSTRACT

To assess the frequency and degree of pituitary hyperplasia in albino rats made hypothyroid by Carbimazole, and the association of severity of pituitary enlargement, and the response to treatment with thyroxine. To determine the microscopic changes occurring in beta basophil cells [Thyroid stimulating hormone and Adreno corticotrophin hormone producing cells] of Anterior Pituitary gland by giving an anti-thyroid drug, Carbimazole and Carbimazol plus, thyroxin on anterior pituitary glands of male albino rats with increasing time period. Experimental study. Anatomy Department, Basic Medical Sciences Institute, Jinnah Postgraduate-Medical Centre Karachi. Forty five healthy, young adult male albino rats were selected for the study. They were distributed into 3 main groups of 15 rats each. Group A served as control while Group B received injection Carbimazole 6 micro g m/G body weight subcutaneously daily. Group-C were treated with injection Carbim arole 6 micro g m/G body weight subcutaneously plus injection Thyroxin 5 micro g m intraperitoneally daily for their respective period of treatment. Each group was further subdivided into three sub-groups according to the period of treatment they received i.e. 2,4 and 6 weeks at the end of which animals were sacrificed. The Pituitary glands were dissected out after processing and staining [Wilson-Ezrin method]. The tissues were subjected to detailed micrometric examination. The-results are based on changes in morphometric study of number and diameter of Beta Basophil cells in anterior Pituitary gland. Mean value of number of Basophils were-increased significantly [P <0.001] in group B [Carbimazole treated] i.e 151.0 +/- 3.38 than group A [control] i.e 82.2 +/- 3.48. While in group C [Carbimazole plus Thyroxin treated] the number of cells were decreased i.e 117.6 +/- 3.83 than group B but were more than group A. Beta Basophil cell size [diameter] was also increased significantly [P <0.001] in group B i.e 17.64 +/- 1.06 than group A 14.45 +/- 3.28. In group C Beta Basophil cell size was 16.16 +/- 2.02, which was more than group A but less than group C. The number and size of Beta Basophils in group C was significant [P<0.05], when compared with corresponding controls. In conclusion these results strongly suggest that Carbimazole-induced hyperplasia and hypertrophy of Anterior pituitary gland may be prevented by simultaneous treatment with Thyroxin. Long standing treatment with Carbimazole in hyperthyroid patients as in Graves disease should accompany, small doses of Thyroxin as well, to avoid the enlargement of Anterior Pituitary gland during their treatment