Thyroid function and dermal purines in the brook trout, Salvelinus fontinalis (Mitchill)

Abstract

Both TSH and thyroid powder significantly increased skin guanine and hypoxanthine levels over a 5-week period at 15 °C. TSH was more effective than thyroid powder.Injected thyroxine as low as 0.05 μg/g body weight per 2 days and ambient thiourea as low as 0.0001% inhibited thyroid function over 3 weeks at 10 °C. This thyroxine treatment did not significantly increase skin purine levels, but thiourea as low as 0.01% significantly decreased skin hypoxanthine and total purinelevels.