SOME MORPHOLOGICAL-CHANGES IN THE RAT-THYROID GLAND DURING EXPERIMENTAL HYPERPHENYLALANINEMIA

Background: Little is known about the effect of phenylketonuria on the thyroid gland, In the present study, this problem was investigated by using a defined experimental model of hyperphenylalaninemia (HPA), Me thods: The experimental group was subjected to an HPA regimen (Matsuo and Hommes. 1988, Neurochem, Res., 13:867-870) from the 5th day of pos tnatal development. The pups were decapitated on the 7th, 14th, 21st, 28th, and 35th days, The thyroid glands were fixed in Bouin's fluid an d routinely embedded in paraffin. The staining techniques used were Ma llory-Slinchenko's method, toluidin blue, silver impregnation of the b asement membrane, immunohistochemical staining of the proliferating ce ll nuclear antigen (PCNA), and neuron-specific enolase (NSE). Results: The size of the follicles was less than that in the control group, Th ere were no substantial changes in the epitheliomer structures. In alm ost all of the treated groups, a reduction in the number of PCNA+, NSE +, and mast cells was observed until the 28th day, On the 28th day of HPA, the level of mast cell degranulation was higher (61%) than that i n the control group, On the 35th day, these parameters began to reach normal levels, From the 28th day, degenerative changes in the thyroid glands of treated animals were observed in the NSE+ cells. Conclusions : The HPA condition mainly has an influence on the number and structur e of the NSE+ cells of the thyroid gland. One may assume that under HP A the increase in mast cell degranulation plays a significant role in the normalisation of the parameter of the thyroid gland. (C) 1997 Wile y-Liss, Inc.