Effect of Calcitonin and 1,25(OH)₂-Vitamin D₃ on the FSH, LH and Testosterone Secretion at Rest and LHRH Stimulated Secretion

 

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Summary

The calcium signal plays an important role in the control of the secretory process of some adenohypophyseal hormones which responds to the administration of calciotropic substances by a marked change. In the submitted work the effect of calcitonin and 1,25(OH)₂-vitamin D₃ (1,25(OH)₂D₃) on FSH, LH and testosterone secretion was investigated.

A single dose of 50 U synthetic salmon calcitonin did not influence the FSH, LH and testosterone secretion at rest nor stimulated secretion. 1,25(OH)₂D₃ administered for four days in amounts of 3 μg/day did not affect the LH and testosterone secretion but increased slightly the secretory response of FSH to LHRH, significantly during the 80th minute following administration of the secretagogue (P < 0.01). The indication of bi-phasic FSH secretion was eliminated by 1,25(OH)₂D₃.

The significant decline of PTH levels following administration of 1,25(OH)₂D₃ is evidence of abiologically effective level of 1,25(OH)₂D₃ attained by the administered dose of hormone.

As compared with the marked effect of calcitonin and 1,25(OH)₂D₃ on thyrotropic hormone secretion, it may be concluded that the gonadotropic system is considerably less sensitive to a change of calcium homeostasis induced by calcitonin or 1,25(OH)₂D₃. Nevertheless a slight increase of the FSH secretion and a change of the dynamics of its secretion suggest a modulating role of 1,25(OH)₂D₃ in the control of FSH secretion.