Effects of phenylbutazone on thyroid iodine metabolism in vitro

Biochemical and functional changes during the bovine fetal thyroid development

To establish biochemical and functional relations during thyroid development, the activity of thyroid peroxidase (TPO), nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductase and monoamine oxidase (MAO) in a particulate fraction and the iodide transport and organification in slices of bovine fetal thyroid were examined throughout gestation. The cytochemical localization of TPO, H2O2 generating sites and MAO was also studied. Fetal glands were grouped in stages I to V according to increasing developmental features; adult tissues were also analyzed. TPO activity in each of the fetal stages was higher than in the adult; a marked increase was observed in stages IV and V. Iodide transport (T/M) was similar in stages I to V and the adult. Iodide organification in fetal thyroids showed a similar pattern to that of TPO activity. When compared with the adult, at midgestation (stages II to III), a lower iodination coexisted with a higher TPO activity. The activity of NADPH-cytochrome c reductase and MAO, two enzymes previously proposed to participate in thyroid H2O2 generation, did not parallel the level of iodide organification. Cells from stages II to V exhibited a positive cytochemical reaction for TPO in the rough endoplasmic reticulum (RER) and the perinuclear cisternae (PC). In stages IV, V, and adult, TPO was occasionally found in apical vesicles and microvilli, whereas H2O2 was detected within the RER and the PC. MAO reaction was positive in adult, but not in fetal thyroid. These results indicate that a high TPO activity accompanied the onset of the organification process during fetal thyroid development. The level of iodination was associated with the presence of TPO at a proper site rather than to the level of TPO activity. Evidence against a role of NADPH-cytochrome c reductase and MAO in the iodide organification was obtained.

The effects of phenylbutazone on the morphology and prostaglandin concentrations of the pyloric mucosa of the equine stomach

Phenylbutazone, a nonsteroidal anti-inflammatory drug known to produce gastric ulcers, was administered intravenously (13.46 mg/kg body weight) daily to 12 horses. Horses were euthanatized daily after 24, 48, 72, and 96 hours following the initial injection. Eight untreated horses served as controls. Small multifocal pyloric erosions were seen after 24 hours and then progressed in severity over time. The erosions were characterized by sloughing of the surface epithelium, subepithelial bleb formation, necrosis of the lamina propria, degeneration of the walls of subsurface capillaries, and microthrombosis of the capillaries of the pyloric mucosa. Large numbers of neutrophils with abundant fibrin and cellular debris were present at the erosion sites. Eroded pyloric mucosa and adjacent macroscopically intact mucosa were examined ultrastructurally. In both the macroscopically eroded mucosa and multifocally in the adjacent macroscopically uneroded mucosa, there was cellular swelling of the endothelium, pericytes, and smooth muscle cells of arterioles. In capillaries and post-capillary venules, the endothelium ranged from swollen to lysed and necrotic. Extensive extravasation of erythrocytes and edema were seen. These lesions were not seen in the control horses. Phenylbutazone produces a microvascular injury that is associated with the formation of pyloric erosions in horses. The pyloric mucosa of six horses was assayed for prostacyclin and prostaglandin E2 at 48 and 96 hours following the initial injection. There was no statistically significant difference between prostaglandin concentrations in the mucosa of control and treated horses. It was concluded that there was little correlation between pyloric mucosal prostaglandin concentrations and pyloric erosions after 48 hours.

A study of thyroid function in the pre- and post-menopause

Serum levels of thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free triidotthyronine (FT3), free thyroxine (FT4) and thyroxine-binding globulin (TBG) were measured in 382 healthy women who were attending a menopause clinic. Of these women, 140 were in the pre-menopausal phase, 162 had been post-menopausal for less than 3 yr and 60 had been post-menopausal for greater than 3 yr. Analysis of the results as a function of climacteric situation, revealed that the only significant difference was a lower serum concentration of FT3 in the women who had been post-menopausal for over 3 yr than in the women who were in the pre-menopausal phase. Statistical analysis of the results as a function of both climacteric situation and age showed that the serum level of TBG increases with age, while serum levels of circulating thyroid hormones decrease, and that although the menopause does not bring about marked changes in thyroid function, it nevertheless tends to reduce that function, especially when menopause occurs at the expected time. Finally, by correlating values with T4 values on an individual basis, it was possible to ascertain that when physiological changes in thyroid function do occur in the climacteric, they are not caused by primary changes in TSH secretion.