Thyroid C cells of middle-aged rats treated with estradiol or calcium

Abstract

The structure and function of C cells of middle-aged female rats (14-months old) treated with estradiol dipropionate (EDP), calcium (Ca) or a combination of EDP+Ca were studied. A stereological method was used to determine the volume of calcitonin (CT)-immunoreactive C cells and their nuclei, and the relative volume density and mean number of the C cells per section were calculated. Serum levels of CT, osteocalcin, parathyroid hormone (PTH), and beta-estradiol were also measured. A significant decrease in body weight of the rats treated with EDP or EDP+Ca was observed. These treatments led to a significant decrease in cellular and nuclear volumes, relative volume density, and mean number of C cells per section, in comparison with the corresponding controls. A reduction of the serum level of CT, PTH, and osteocalcin was also recorded in EDP- and EDP+Ca-treated animals. No statistically significant differences between Ca- and vehicle-injected rats, with regard to all morphometric C cell parameters and biochemical values determined, were seen. However, a conspicuous degranulation of the C cells and decreased immunoreactivity for CT in the Ca-receiving group, which could be interpreted as the signs of increased activity of these cells, were noticed. This effect of Ca was also observed in rats injected with EDP and Ca in combination, when the inhibitory effect of EDP on C cell function was less noticeable than in the group treated with EDP alone.

The effect of orchidectomy on thyroid C cells and bone histomorphometry in middle-aged rats

“…This is consistent with previously reported ageassociated hyperplasia of C cells (Delverdier et al 1990;Sekulić et al 1998) and hypercalcitoninemia in rats (Lu et al 2000).…”

“…In aged rats, physiological hyperplasia of C cells (Delverdier et al 1990;Sekulić et al 1998) and hypercalcitoninemia were noticed together with lower levels of testosterone (Lu et al 2000). Orchidectomy in aged male rats resulted in a decrease of both plasma and thyroid CT release in vitro (Lu et al 2000).…”

“…After rehydration, the sections were stained immunocytochemically. CT in the C cells was displayed using the peroxidase-antiperoxidase (PAP) method (Strenberger et al 1970), as previously described by Sekulić et al (1998). Anti-human CT antiserum (Dakopatts, Copenhagen, Denmark) diluted 1:500 served as the primary antibodies.…”

Chronic Estradiol Exposure Modulates Thyroid Structure and Decreases T₄ and T₃ Serum Levels in Middle-Aged Female Rats

“…A more probable indirect mechanism by which estradiol might have affected the level of thyroid hormones in EDP-treated rats is hormone-related weight loss. We have previously shown that the body weight of middle-aged females was significantly decreased after EDP treatment [31], which is also confirmed in this experiment. Estradiol could have influenced eating behavior and energy balance [32], thus contributing to the detected decrease of thyroid hormones under our experimental conditions.…”

Daidzein administration positively affects thyroid C cells and bone structure in orchidectomized middle-aged rats

“…The laryngeal area with thyroid lobes from each animal was fixed in Bouin's solution, embedded in paraplast, and cut into 5 μm thick longitudinal serial sections. The sections were immunostained using the peroxidase-antiperoxidase (PAP) method [26] for localization of CT in the C cells, as described by Sekulić et al [27]. Antihuman CT antiserum (Dakopatts, Copenhagen, Denmark) diluted 1:500 served as the primary antibodies.…”