Plasma Calcitonin Levels in Birds During the Ovulation Cycle

Inhibition of Osteoclastic Bone Resorption by Calcitonin in the Cultured Medullary Bone of Laying Hens.

“…Calcitonin receptors have been demonstrated to be present in mammalian osteoclasts (WARSHAWSKY et al, 1980;NICHOLSON et al, 1986), indicating calcitonin to directly act on osteoclasts. It has been reported that circulating calcitonin levels fluctuate during the egg laying cycle (DACKE et al, 1972 doses of calcitonin ( Fig. 3 and 4).…”

Calcitonin Receptor Binding Properties in Bone and Kidney of the Chicken During the Oviposition Cycle

“…The plasma CT level significantly decreases at 14 -22 h after ovulation, corresponding to the time of egg shell calcification. (21) Decreases of B max values of bone and renal CT receptors in the laying hens therefore may be a conse- quence of an increase in the binding of CT to its receptors in vivo by an increase in the affinity. Similar phenomena of CT receptors have been observed in human neoplasmic cells having CT receptors (44) and cultured rat bone cells (45) in vitro as well as rat kidney tissue (46) in vivo.…”

“…(20) Plasma CT levels in Japanese quail fluctuate during an ovulation cycle; the level significantly decreases at 14 -22 h after ovulation, corresponding to the time of eggshell calcification. (21) CT therefore might play a role on the calcium metabolism of the laying bird, particularly during the ovulation-oviposition cycle. Previously we found that the binding affinity of PTH receptor in the bone and the kidney of egg-laying hens increased during the period between 3 h before oviposition and the time of oviposition with a concomitant decrease in the binding capacity.…”

Calcitonin receptor binding in the hen neurohypophysis before and after oviposition

“…Although it is obscure what is the trigger of CT action on neurohypophysis at a close time of oviposition, the initial CT action may be caused by an increase in plasma CT levels. The plasma CT level increases at no calcification time in the Japanese quail (Dacke et al, 1972), although such reports are not found in the chicken. On the other hand, it has been reported that CT is produced in the pituitary gland and hypothalamus of avian species (Galan 1 Nonlaying hens received a single i.v.…”

“…The presence of CT receptor has been reported in the oviduct uterus (shell gland; Ieda et al, 2001), the kidney, and the bone (Yasuoka et al, 1998) in hens, and its binding change in relation to the eggshell calcification during an oviposition cycle (Yasuoka et al, 1998;Ieda et al, 2001). In the Japanese quail, plasma CT levels change during the oviposition cycle (Dacke et al, 1972). The egg stays in the uterus for approximately 20 h (Warren and Scott, 1935) and is expelled from the uterus outside the body through the vagina (Jull, 1952) by the contraction of uterine smooth muscle (Gilbert, 1971).…”