April - June 2010, Volume 6, Issue 2

Sinha BR, Chakraborty S

Pineal-thyroid karyomarphology and function in resonse to diversely altered serum T4 levels in rat (rattus rattus)

Acta Endo (Buc) 2010, 6 (2): 151-163
doi: 10.4183/aeb.2010.151

Background. The pineal cytomorphological responsiveness to altered serum T4 levels awaits any comprehensive investigations in mammals .\r\nAim. The aim of the present investigation was to use rats with diversely altered serum T4 level, to study the pineal karyomorphology and functions.\r\nMaterials and Methods. Five groups each with 11 rats were used as controls and T4 (50&#956;g/100g b.w.) for seven consecutive days, thyroidectomized and kept for thirty days and additionally such TX rats, treated with T4 (50&#956;g/100g b.w.) for seven days, were used for pineal karyometry and serum T4 analysis.\r\nResults. They indicated that thyroxine administration evoked hyperactive changes in pineal gland cytomorphology along with enhanced serum T4, as evidenced from increased\r\npinealocyte nuclear diameter (&#956;m) (C 4.71+0.03,T4 5.14+0.04,p<0.001) and decreased nuclear density (C 179.44+4.78,T4 126+4.36,p<0.001) and enhanced serum T4 level\r\n(&#956;g/dL), (C 3.60+0.13,T4 13.40+1.75,p<0.001). Contrarily, thyroidectomized (TX) rats with undetectable T4 levels (<0.05 &#956;g/dL) showed pineal inhibition, as seen from significantly decreased pinealocyte nuclear diameter (&#956;m) (C 4.71+0.03,Tx 4.01+0.04,p<0.001) values, and an increased nuclear density per microscopic field (C179.44+4.78, Tx 208.8+4.47, p<0.005). However, thyroidectomized animals, supplemented with thyroxine (Tx + T4), induced pineal activation as seen from increased pinealocyte nuclear diameter, &#956;m (C 4.71+0.03, Tx + T4 5.26+0.05, p<0.001) associated with increased serum T4 level &#956;g/DL (C 3.60+0.13, Tx+T4 10.92+0.13m p<0.001).\r\nConclusion. The present study argues for a direct pineal-thyroid relationship as interpreted from cytomorphological level and hormone profiles in male albino rats.

Keywords: pineal; thyroid; karyomorphology; T4; rat

Correspondence: Subrata Chakraborty, University of Calcutta - Department of Zoology 35, Ballygunge Circular Road, Kolkata, West Bengal 700019, India, Email: subratachakraborty2000@yahoo.co.in