Title: Influence of age, strain and season on diurnal periodicity of thyroid stimulating hormone, thyroxine, triiodothyronine and parathyroid hormone in the serum of male laboratory rats
Abstract: Abstract. The influence of age, strain and season on the diurnal pattern of serum hormone levels from the pituitary-thyro-parathyroid complex was studied in male laboratory rats. Distinct 24 h periodicity in the serum levels of thyroid stimulating hormone (TSH) and triiodothyronine (T 3 ) was observed in all groups of rats. There was no influence of age (40, 60 and 90 days old Sprague-Dawley rats), but a significant influence of strain (Sprague-Dawley vs. BH/Ztm rats) and season (summer vs. winter) on the diurnal pattern of serum TSH and T 3 levels. Significant 24 h periodicity in serum thyroxine (T 4 ) levels existed during winter in BH/Ztm rats, but not in Sprague-Dawley (SD) rats of any age. Adult SD rats demonstrated 24 h periodicity in serum levels of T 4 only in summer. No diurnal periodicity in serum levels of parathyroid hormone (PTH) was observed in any group of rats. There were significant changes in 24 h mean serum levels of TSH and T 3 throughout pubertal development. Twenty-four h mean serum levels of T 3 and T 4 were significantly higher in summer than in winter. Twenty-four h mean serum levels of T 4 were significantly lower in BH/Ztm rats than in SD rats. Significant correlation was observed between serum concentrations of T 3 and T 4 , TSH and T 4 , and between TSH and T 3 in some groups of rats, but not in all. The results indicate that 24 h periodicity of serum hormone levels from the pituitary-thyroid complex of male laboratory rats may vary with age and strain of the animals and with the season of experiment performance.
Publication Year: 1983
Publication Date: 1983-03-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 42
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