A quantitative study of peroxidase activity in unfixed tissue sections of the guinea-pig thyroid gland |
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| Authors: | Patricia A Ealey B Henderson and N Loveridge |
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| Institution: | (1) Department of Molecular Endocrinology, The Middlesex Hospital Medical School, W1N 8AA London, UK;(2) Division of Cellular Biology, Kennedy Institute of Rheumatology, 6 Bute Gardens, W6 7DW London, UK;(3) McGill University Clinic, Royal Victoria Hospital, H3A 1A1 Montreal, Quebec, Canada;(4) Present address: Department of Chemical Pathology, King's College Hospital Medical School, Denmark Hill, SE5 London, UK;(5) Present address: Division of Cellular Biology, Kennedy Institute of Rheumatology, 6 Bute Gardens, W6 7DW London, UK |
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| Abstract: | Summary A technique for the cytochemical demonstration of peroxidase activity in unfixed guinea-pig thyroid tissue is described in this paper. The substrate 3,3 -diaminobenzidine tetrahydrochloride (DAB) is oxidized by the peroxidase to form an insoluble reaction product. Optimal results were obtained after 20 min incubation at 37° C in reaction medium containing 1.4mm DAB (in 0.1m Tris-HCl) and 0.15mm hydrogen peroxide at pH 8.0. Peroxidase activity was seen in the thyroid follicle cells as a diffuse brown reaction product (which was more dense and granular in erythrocytes). The enzyme activity was quantified using a scanning-integrating microdensitometer, and the effects of two specific peroxidase inhibitors were evaluated. Both 3-amino-1,2,4-triazole and methimazole inhibited peroxidase activity in the follicle cells (enzyme activity was still seen in the erythrocytes), maximal inhibition occurring at 10mm. Stimulation of peroxidase in the thyroid was observedin vivo (1 I.U. TSH administered every 8 h for two days), with the maximal stimulation occurring after 1 day. |
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