Características do osso alveolar mandibular de fêmeas de camundongos ovariectomizadas e tratadas com ácidos húmicos

Abstract

Menopause is the definitive cessation of menstruation after 12 consecutive months, marking the end of the reproductive phase due to the depletion of ovarian follicles. This process generates hormonal fluctuations, with an elevation of gonadotropins and a drastic drop in estrogen production, triggering systemic impacts that extend beyond the reproductive system. This hormonal deficiency may favors the development of cardiovascular diseases, diabetes, hypertension, osteoporosis, and alveolar bone loss. Regarding treatment, gaps remain concerning natural substances with anti-inflammatory potential that are safe and low-cost. Humic Acids (HA) are organic components with flexible conformations and complex structures, showing promising properties to minimize the bone structure damage caused by menopause. Thus, in order to investigate therapeutic alternatives for the repercussions of this physiological process that occurs in women, the objective of this study was to evaluate the effects of systemic administration of HA on the mandibular alveolar bone of ovariectomized female mice. Twenty-four female C57BL/6 mice were used, distributed into four groups (n = 6/group): Sham-operated group treated with saline solution (Sham), ovariectomized group treated with saline solution (OVX), sham-operated group treated with humic acid (Sham + HA), and ovariectomized group treated with humic acid (OVX + HA). The experimental model of estrogen depletion was induced by bilateral ovariectomy. Subsequently, the animals underwent administration via gavage of HA derived from vermicomposting, at a daily dose of 80 mg/kg, for 28 days. After euthanasia, the mandibles were collected and analyzed regarding: elemental composition and topography of the mandibular bone using Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDS), histomorphometric analysis of alveolar bone loss, and immunohistochemical analysis: Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL), Osteoprotegerin (OPG), and Tartrate-Resistant Acid Phosphatase (TRAP). Data were analyzed using Analysis of Variance (ANOVA) and Bonferroni's post hoc test, adopting p < 0.05 as the level of significance. The results demonstrated that the animals treated with saline solution exhibited greater irregularities, porosity, and roughness compared to the other experimental groups, analyzed qualitatively. The animals submitted to OVX with saline administration showed greater alveolar bone loss compared to the animals also submitted to OVX but treated with HA. Regarding calcium and phosphorus content, a significant reduction of these elements was observed in the animals of the OVX group compared to the Sham group (p < 0.05). However, the ovariectomized females treated with HA showed higher content of these elements compared to the untreated ones (p < 0.05). It is concluded that HA treatment improves bone integrity, elemental composition, as well as bone resorption markers of the mandibular alveolar bone.