Yuichi Sasayama

Cells showing immunoreactivity for calcitonin or calcitonin gene-related peptide (CGRP) in the central nervous system of some invertebrates.

In the central nervous system of some species of several invertebrate phyla, including land planarians (Platyhelminthes), ribbon worms (Nemertina), slugs (Mollusca), polychaetes, earthworms and leeches (Annelida), pill bugs (Arthropoda), and beard worms (Pogonophora), salmon calcitonin-immunoreactive cells and rat calcitonin gene-related peptide (CGRP)-immunoreactive cells were found by immunohistochemistry. These immunoreactive cells were located in the region surrounding the neuropile, although the sizes of the cells varied according to species. Some of them were round or polygonal and regarded as apolar nerve cells because of their lack of cytoplasmic processes, whereas others were spindle-shaped or elongated, being comparable with unipolar nerve cells because of extension of their cytoplasmic processes in the direction of the neuropile. In some cases, it was noted that the cytoplasmic processes had complicated branches or formed loop-like structures at their ends. These observations suggest that a calcitonin-like or CGRP-like substance is extensively present in invertebrates as well as vertebrates.

The role of parathyroid hormone on renal excretion of calcium and phosphate in the Japanese quail

Abstract Renal excretion patterns were investigated in male Japanese quail, Coturnix coturnix japonica, after administration of avian saline, parathyroid extract (PTE), or after parathyroidectomy (PTX). Consistent long-term effects of parathyroid hormone were on excretion of phosphate, which increased significantly by 40 min after hormone administration and remained at high levels for approximately an hour. Phosphate secretion occurred in response to the hormonal stimulus. Serum calcium values also increased significantly for the first 2 hr after hormone injection. PTX quail had consistently lower GFR (CIn), which correlated with decreased inulin U P ratios and decreased amounts of sodium reabsorption by the renal tubules (TNa). PTX also resulted in decreased tubular reabsorption of calcium (Tca) but in this case the fractional excretion of calcium ( C Ca C In , which corrects for changes in GFR) was elevated. Thus the lack of hormone resulted in a significant increase in urinary calcium loss. This correlated with a steady development of hypocalcemia after PTX. Tubular reabsorption of phosphate (TPO4) increased and fractional excretion of phosphate ( C PO 4 C In ) gradually decreased following PTX leading to significantly lower phosphate excretion values by 3 hr after PTX.

Calcitonin of the stingray: Comparison of the hypocalcemic activity with other calcitonins

Hypocalcemic potency of calcitonin isolated from the stingray (cartilaginous fish), Dasyatis akajei, was examined using the rat bioassay and compared with the activities of other calcitonins (human, pig, salmon, eel, and fowl). The potency of Dasyatis calcitonin (dCT) was estimated to be 1500-3800 IU/mg. However, when the duration of the hypocalcemic effect of dCT was taken into consideration, it was judged that dCT was approximately 2.4-6.2 times more potent than mammalian calcitonins, but about 2.3-3.5 times less active than other nonmammalian calcitonins.

Effects of implantation of the ultimobranchial glands and the administration of synthetic salmon calcitonin on serum Ca concentrations in ultimobranchialectomized bullfrog tadpoles

Serum Ca concentrations in ultimobranchialectomized bullfrog tadpoles increased markedly in a high Ca environment. However, tadpoles implanted with the ultimobranchial glands of bullfrog tadpoles, or of Rana nigromaculata, showed no changes in serum Ca levels. The administration of synthetic salmon calcitonin (5 MRC units per individual) to the ultimobranchialectomized tadpoles partially suppressed the acute rise of serum Ca concentrations in a high Ca environment.

Effects of ultimobranchialectomy on calcium and sodium concentrations of serum and coelomic fluid in bullfrog tadpoles under high calcium and high sodium environment

Abstract 1. 1. The role of the ultimobranchial gland of bullfrog tadpoles on the regulation of calcium and sodium levels in serum and coelomic fluid was studied by means of ultimobranchialectomy. 2. 2. Calcium levels in serum and coelomic fluid in the ultimobranchialectomized tadpoles increased markedly after 48 hr treatment with high calcium and sodium media, although no changes were found in these levels in tap water. 3. 3. The tendency to hyponatremia was more pronounced in the ultimobranchialectomized tadpoles than in the sham-operated. 4. 4. It is concluded that one of the functions of the ultimobranchial gland of the anuran larva is to suppress the acute rise of calcium levels in body fluid.

CHANGES IN CALCIUM CONCENTRATIONS OF SERUM AND COELOMIC FLUID OF THE BULLFROG, RANA CATESBEIANA, DURING LARVAL DEVELOPMENT AND METAMORPHOSIS

The serum calcium levels of bullfrog tadpoles (stage 26 to 33) and adults are higher than those of the coelomic fluid. The serum levels increase gradually from stage 26 (7.6 mg/100 ml) to stage 30 (8.4 mg/100 ml), and then sharply to stage 33 (10.5 mg/100 ml), while the coelomic fluid levels increase from 7.1 to 8.7 mg/100 ml during this period. Only minor differences are found in serum and coelomic fluid sodium levels among larval stages with the exception of a temporary decrease during metamorphic climax.

Effects of hypophysectomy and replacement therapy with pituitary homogenates or ovine prolactin on serum calcium, sodium, and magnesium concentrations in bullfrog tadpoles

Abstract Hypophysectomy in bullfrog tadpoles kept in tap water caused a slight but significant hypocalcemia and a hyponatremia at 7 days after the operation. When hypophysectomized tadpoles were kept in high-sodium water (Na, 100 mg/100ml), although the decrease of serum sodium concentrations was blocked, the lowered calcium level remained unchanged. Pituitary homogenate injections of tadpoles (1.5 glands/individual/day) for 4 days increased serum calcium and sodium concentrations in hypophysectomized tadpoles kept in tap water. Administrations of ovine prolactin (25 IU/individual/day) also brought about an increase in the calcium level, but failed to correct the decrease of serum sodium concentrations. It was suggested that in bullfrog tadpoles the pituitary gland, probably by prolactin, participates in increasing serum calcium concentrations.

Hypocalcemic factor in the ultimobranchial gland of the frog, Rana rugosa

1. n1. The hypocalcemic activity of the ultimobranchial gland of the frog, Rana rugosa, was estimated using a rat bioassay method. n n2. n2. Extracts of the ultimobranchial gland showed a very high hypocalcmic activity. The value corresponded to 6,340 mU (MRC)/kg b.w. n n3. n3. Serum inorganic phosphorus values of rats received the extract decreased in proportion to the dose, although no changes were found in serum sodium concentration.

Morphology and function of the parathyroid gland of the caiman, Caiman crocodilus.

Abstract The juvenile caiman, Caiman crocodilus , possesses two to six parathyroid glands which are embedded in the thymus, one to three on either side of the body. The number is subject to individual variation. In specimens having three parathyroids on one side of the body, the smallest may be designated as an accessory parathyroid. The parathyroid gland is composed of parenchymal cells arranged in cords among which rich connective tissue and blood capillaries are present. The general features of the parathyroid histology of the present specimens resemble those reported in other groups of reptiles. Normal serum calcium, sodium, and phosphorus concentrations are 15.2 ± 0.30, 332.7 ± 2.42, and 3.4 ± 0.32 mg/100 ml, respectively. Surgical parathyroidectomy caused a significant decrease of serum calcium concentration (about 50–60% of the normal) 5 and 10 days after the operation together with simultaneous occurrence of tetanic convulsions. However, no changes were observed in serum sodium concentrations. Serum phosphorus concentration increased 5 days after parathyroidectomy. Administration of mammalian parathyroid extract (0.2 USP units/g body wt) partially corrected the hypocalcemia which was caused by parathyroidectomy. The present results suggest that the role of the crocodilian parathyroid gland in serum calcium and phosphorus homeostasis is very similar to that of the Squamata but somewhat different from that of the Chelonia.

Function of the parathyroid gland in serum calcium regulation in the newt, Tylototriton andersoni Boulenger

Abstract Parathyroidectomy in juvenile Tylototriton andersoni brought about hypocalcemia 5 and 10 days after the operation. However, 30 days later serum Ca concentrations returned to a nearly normal level. Serum Na concentrations did not change after parathyroidectomy. Hypocalcemia in parathyroidectomized Cynops pyrrhogaster , a newt, was partially corrected by the implantation of the parathyroid glands of T. andersoni . Mammalian parathyroid extracts seem to be effective in increasing serum Ca concentration in C. pyrrhogaster and T. andersoni . These results suggest that the role of the parathyroid gland of T. andersoni in serum Ca homeostasis is very similar to that of C. pyrrhogaster .