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Immunoreactive parathyroid hormone levels in platyrrhini and catarrhini: A comparative analysis with three different assays
Author(s) -
Adams John S.,
Gacad Mercedes A.,
Rude Robert K.,
Deseran Mark,
Endres David B.,
Mallette Lawrence E.
Publication year - 1987
Publication title -
american journal of primatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.988
H-Index - 81
eISSN - 1098-2345
pISSN - 0275-2565
DOI - 10.1002/ajp.1350130407
Subject(s) - parathyroid hormone , medicine , endocrinology , antiserum , vitamin d and neurology , hyperparathyroidism , hormone , biology , tertiary hyperparathyroidism , secondary hyperparathyroidism , antibody , calcium , immunology
Serum concentrations of the hormonal form of vitamin D 3 —1,25‐dihydroxy‐vitamin D 3 [1,25‐(OH) 2 ‐D 3 ]—are elevated in many genera of platyrrhines when compared to catarrhines; this elevation is presumed to result from a decrease in the ability of the target cell receptor effectively to recognize 1,25‐(OH) 2 ‐D 3 . The activity of the renal 25‐hydroxyvitumin D 3 ‐1α‐hydroxylase, the mammalian enzyme which synthesizes the majority of the circulating 1,25‐(OH) 2 ‐D 3 , is accelerated by parathyroid hormone (PTH). In order to determine whether the elevated serum concentrations of 1,25‐(OH) 2 ‐D 3 in platyrrhines were the result of relative hyperparathyroidism, we measured serum levels of immunoreactive parathyroid hormone (iPTH) in normocalcemic platyrrhines, catarrhines, and human subjects with assays that recognize different domains of the human PTH molecule. Antisera directed against the biologically active, aminoterminus of PTH yielded comparable mean values for iPTH among three test groups. The mean concentration of iPTH as assessed by a “proximal” midregion assay was significantly reduced in platyrrhine serum when compared to either human or catarrhine serum. A “distal” midregion assay yielded a reduced mean value for iPTH in both platyrrhine and catarrhine serum when compared to human serum. These data suggest that 1) high circulating levels of 1,25‐(OH) 2 ‐D 3 in New World primates are not the result of hyperparathyroidism; and 2) structural homology between human and primate PTH diminishes progressively as one moves toward the carboxyterminus of the molecule and is lost more rapidly in the platyrrhine than in the catarrhine hormone.