Effects of the administration of corticosterone, parathyroid hormone, or both, and of their withdrawal, on rat bone and cartilage histomorphometric parameters, and on osteoprotegerin and RANKL mRNA expression and proteins.

We have studied the effects of the treatment with corticosterone (CORT), parathyroid hormone (PTH), or both (CORT + PTH), and of their withdrawal (CORT-rec and CORT + PTH-rec), on the osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) localization and expression and on histomorphometric parameters in primary and secondary spongiosa of rat femur and tibia metaphyses. In the secondary spongiosa of the CORT group, the bone remodeling and the OPG/RANKL mRNA ratio decreased. In the PTH group, the bone turnover and the structural and connectivity indices increased, and the OPG/RANKL mRNA ratio fell; this ratio rose, however, in the primary spongiosa. In the CORT + PTH group, remodeling values intermediate between those of the CORT and PTH groups, were detected in the secondary spongiosa, where OPG and RANKL mRNA rose. Return towards control values was found in the recovery groups. The Cartilage Growth Plate Width was reduced in the CORT and CORT + PTH groups and returned to normal values in the recovery groups, while it was not affected by PTH. Independently of treatments, both OPG and RANKL mRNA and proteins were co-localized in the same cartilage and bone cells and in several bone marrow cells. In conclusion, the catabolic effects induced by CORT treatment occur together with an OPG fall and a RANKL rise. In the PTH group in which the bone turnover increase, the OPG and RANKL mRNA expressions differ in the primary and secondary spongiosa, confirming that the bone tissue in these sites can have different metabolic trends.

Detection of osteoprotegerin (OPG) and its ligand (RANKL) mRNA and protein in femur and tibia of the rat.

Osteoprotegerin (OPG) and the receptor activator of nuclear factor (NF)-kB ligand (RANKL) are key regulators of osteoclastogenesis. The present study had the main aim of showing the localization of OPG and RANKL mRNA and protein in serial sections of the rat femurs and tibiae by immunohistochemistry (IHC) and in situ hybridization (ISH). The main results were: (1) OPG and RANKL mRNA and protein were co-localized in the same cell types, (2) maturative/hypertrophic chondrocytes, osteoblasts, lining cells, periosteal cells and early osteocytes were stained by both IHC and ISH, (3) OPG and RANKL proteins were mainly located in Golgi areas, and the ISH reaction was especially visible in active osteoblasts, (4) immunolabeling was often concentrated into cytoplasmic vacuoles of otherwise negative proliferative chondrocytes; IHC and ISH labeling increased from proliferative to maturative/hypertrophic chondrocytes, (5) the newly laid down bone matrix, cartilage-bone interfaces, cement lines, and trabecular borders showed light OPG and RANKL immunolabeling, (6) about 70% of secondary metaphyseal bone osteocytes showed OPG and RANKL protein expression; most of them were ISH-negative, (7) osteoclasts were mostly unstained by IHC and variably labeled by ISH. The co-expression of OPG and RANKL in the same bone cell types confirms their strictly coupled action in the regulation of bone metabolism.

Salivary cortisol, dehydroepiandrosterone-sulphate (DHEA-S) and testosterone in women with chronic migraine.

Hypothalamus-pituitary-adrenal (HPA) axis activity was monitored in 20 women with chronic migraine (CM), previously affected by medication overuse headache (MOH), in comparison to healthy women (20 subjects) by measuring salivary cortisol, testosterone, dehydroepiandrosterone-sulphate (DHEA-S) levels, and their ratios, one week after the end of the MOH rehabilitation procedure. The participants were instructed how to collect saliva samples at home, a procedure that was performed twice a day (08:00 a.m. and 8:00 p.m.). Morning and evening levels of cortisol were significantly increased in CM patients with respect to controls. With regard to the cortisol/DHEA-S ratio, an inverse marker of psycho-physical wellbeing, CM women showed significantly higher values than controls. Moreover, testosterone/cortisol ratios (anabolic/catabolic index of physical performance) were significantly lower in CM patients than in controls. In the present study, CM appears not to be associated with an impairment of cortisol and DHEAS circadian fluctuation; however, CM patients present alterations in HPA axis function that might contribute to metabolic and psychological alterations that have also been associated with CM.