Mirex-induced adaptive liver growth in rats subjected to thyroidectomy
✍ Scribed by James D. Yarbrough; Jo M. Grimley; Jaideep V. Thottassery
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 565 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0270-9139
No coin nor oath required. For personal study only.
✦ Synopsis
The organochlorine compound mirex (dodecachlorooctahydro-1,3,4-metheno-2H-cyclobuta-CD-pentalene) induces an adaptive liver growth dependent on the hormonal status of the experimental animal. In the intact laboratory rat, mirex induces liver growth that is an expression of both cellular hyperplasia and hypertrophy. However, in rats subjected to adrenalectomy, mirex induces liver growth that is essentially hyperplastic. Corticosterone supplements given to rats subjected to adrenalectomy and treated with mirex restore the hypertrophic component of liver growth. Therefore it appears that the expression of the hypertrophic component of mirex-induced liver growth is corticos terone dependent.
To further explore the hormonal modulation of the expression of mirex-induced adaptive liver growth, rats subjected to thyroidectomy were studied. In male rats subjected to thyroidectomy, a single oral dose of mirex (100 mgkg body wt) increased relative liver weight (liver wt/body wt x 100) by 62% within 72-hr after mirex administration. Liver growth occurred in the absence of ['Hlthymidine incorporation into liver DNA. Thus the observed liver growth was totally hypertrophic. However, in mirex-dosed rats subjected to thyroidectomy given twice-daily subcutaneous injections of thyroxine (5 mgkg body wt), relative liver weight was increased by 204% of the control value within 72-hr after mirex administration, and there was a peak of [3H]thymidine incorporation into liver DNA 54 hr after mirex administration. These studies suggest that the expression of hyperplasia in mirex-induced adaptive liver growth is thyroxine dependent. (HEPA-TOLOGY 1992;15:923-927.) The relationship between the expression of mirexinduced adaptive liver growth and endocrine function was first reported in studies in which the increase in relative liver weight (RLW) was significantly reduced in mirex-dosed ADX rats (rats subjected to adrenalectomy) compared with the RLW increase in mirex-dosed intact rats (1,2). The response appeared to be dependent on the pituitary-adrenalcortical axis (3). When L3H] thymidine