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[SEASONAL DIFFERENCES IN THE EFFECT OF MELATONIN ON THE MORPHO-FUNCTIONAL STATE OF THE THYROID GLAND SPONTANEOUSLY
Rossiiskii Fiziologicheskii Zhurnal Imeni I.M. Sechenova
|September 8, 2018
Summary
Melatonin administration affected thyroid gland activity differently in young, spontaneously hypertensive rats depending on the season. Spring administration boosted thyroid activity, while autumn administration reduced it.
Area of Science:
- Endocrinology
- Chronobiology
- Pharmacology
Background:
- The thyroid gland regulates metabolism and is influenced by various factors, including hormones and environmental cues.
- Melatonin, a hormone primarily involved in circadian rhythms, may interact with thyroid function.
- Spontaneously hypertensive rats (SHR) serve as a model for studying cardiovascular and metabolic conditions.
Purpose of the Study:
- To investigate the seasonal effects of exogenous melatonin on thyroid gland indicators in young spontaneously hypertensive rats.
- To determine if melatonin administration influences thyroid hormone synthesis and secretion differently in spring versus autumn.
Main Methods:
- Young spontaneously hypertensive rats were administered melatonin (5 mg/kg) for 28 days.
- Thyroid gland indicators were assessed, including follicular colloid area, follicle diameter, thyrocyte height, and connective tissue elements.
- Histological analysis was used to evaluate changes in thyroid gland morphology and function.
Main Results:
- In spring, melatonin administration increased thyroid gland synthetic activity, evidenced by reduced follicular colloid area and follicle diameter, and increased thyrocyte height.
- Melatonin also increased the follicular colloidal index and reduced colloid accumulation index in spring, indicating enhanced thyroid function.
- In autumn, spontaneously hypertensive rats showed reduced sensitivity to melatonin, with increased connective tissue elements and decreased follicular epithelium area and follicular colloidal index, suggesting impaired thyroid function.
Conclusions:
- Exogenous melatonin exerts season-dependent effects on thyroid gland activity in young spontaneously hypertensive rats.
- Melatonin enhances thyroid gland synthetic activity in spring but appears to suppress it in autumn.
- These findings highlight the complex interplay between melatonin, seasonal changes, and thyroid function in this hypertensive rat model.
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