Calcium regulating hormones during the estrous cycle of the rat.
Plasma levels of calcium (Ca), phosphate (P), calcitonin (CT), parathyroid hormone (PTH), and prolactin (PRL) were measured at 8, 13, and 17 hr during the 4-day estrous cycle of the rat. Ca levels fell throughout the day during proestrus (PE) and estrus (E). In contrast Ca rose transiently during diestrus (D1, D2). P levels fluctuated inconsistently at all stages of the cycle with the exception of E where P levels were significantly higher at 13 hr. CT levels showed an increase during D1 and D2 and fell to their lowest values during E, at 13 hr. Daily fluctuations in each stage were also recorded. Variations of PTH levels during the estrous cycle were minor. PRL levels increased sharply during PE. No direct relationship between PRL secretion and CT secretion could be established. These results indicate that CT but not PTH varies specifically in relation to the estrous cycle. They suggest that there is a link between sexual hormones and CT, apparently independent of plasma calcium levels.
D000818:Animals; D002116:Calcitonin / Q000097:blood*; D002118:Calcium / Q000097:blood*; D004031:Diestrus; D004971:Estrus; D005260:Female; D010281:Parathyroid Hormone / Q000097:blood*; D010710:Phosphates / Q000097:blood*; D011247:Pregnancy; D011359:Proestrus; D011388:Prolactin / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains
D010281:Parathyroid Hormone; D010710:Phosphates; D011388:Prolactin; D002116:Calcitonin; D002118:Calcium