Effect of cadmium chloride toxicity on olfactory mucosa / Efecto de la toxicidad del cloruro de cadmio en la mucosa olfativa

SUMMARY: Cadmium is a highly toxic metal and affects the respiratory mucosa. The aim of the study is to show the inflammation and degenerative effect of cadmium on the olfactory mucosa. In this study, eight-week-old Wistar rats with an average weight of 170-190 g were divided into two groups (control and experiment) with 20 animals in each group and used in the experiments. The rats in the experimental group were given 2 mg/kg/day powdered cadmium chloride dissolved in water intraperitoneally every day for two weeks. At the end of the experiment, the nasal cavity was completely removed with anesthesia. Concha nasalis superior was separated, fixed with zinc-Formalin solution and decalcified with 5 % EDTA (Ethylene-diaminetetraacetic acid). After routine histopathological procedure, APAF-1 antibody was used for expression of Hematoxylin-Eosin (HE) and immunohistochemistry. Histopathological examination revealed interruptions in the basement membrane structure due to cadmium and degenerative changes in stem cells, degeneration in sensory cells and pycnosis in nuclei, dilatation in blood vessels and increased inflammation in connective tissue. APAF-1 expression was found to increase in epithelial cells and olfactory glands (Bowman gland) cells. It has been thought that cadmium toxicity increases cell degeneration and inflammation in the olfactory mucosa and may significantly affect cell death and olfactory metabolism by inducing the pro-apoptotic process.

El cadmio es un metal altamente tóxico que afecta la mucosa respiratoria. El objetivo fue mostrar el efecto inflamatorio y degenerativo del cadmio sobre la mucosa olfativa. En este estudio, ratas Wistar de ocho semanas de edad con un peso promedio de 170-190 g se dividieron en dos grupos (control y experimental) con 20 animales en cada grupo. Las ratas del grupo experimental recibieron 2 mg/kg/día de cloruro de cadmio en polvo disuelto en agua por vía intraperitoneal todos los días durante dos semanas. En los animales se exirpó la cavidad nasal bajo anestesia. Se separó la concha nasal superior, se fijó con solución de zinc-Formalina y se descalcificó con EDTA (ácido etilendiaminotetraacético) al 5 %. Después del procedimiento histopatológico de rutina, Hematoxilina- Eosina (HE) e inmunohistoquímica, se utilizó el anticuerpo APAF-1. El examen histopatológico reveló interrupciones en la estructura de la membrana basal debido al cadmio y cambios degenerativos en las células madre, degeneración en las células sensoriales y picnosis en los núcleos, dilatación de los vasos sanguíneos y aumento de la inflamación en el tejido conjuntivo. Se encontró que la expresión de APAF-1 aumenta en las células epiteliales y en las células de las glándulas olfatorias (glándulas de Bowman). Se ha pensado que la toxicidad del cadmio aumenta la degeneración celular y la inflamación en la mucosa olfativa y puede afectar significativamente la muerte celular y el metabolismo olfativo al inducir el proceso proapoptótico.

Natriuretic peptides in the rat ofactory system

The olfactory system plays an important role in the mobilization of animal behaviour, along with the sense of taste. These functions are mediated by a complex olfactory structure composed of peripheral (olfactory epithelium) and central (olfactory bulb) components. Several neuropeptides are synthesized in the olfactory system and are believed to be involved in olfactive processing. Recently, another bioactive substance, atrial natriuretic peptide (ANP), has been demonstrated in the olfactory system. ANP is a potent diuretic, natriuretic and vasorelaxant hormone which, originally, was isolated from mammalian atria, but its gene is expressed in many loci. ANP is only one member of the natriuretic peptide (NP) family, which includes two other peptides, BNP (brain natriuretic peptide) and CNP (C-type natriuretic peptide) derived from different genes. All three peptides show many common features. A high concentration of ANP-immunoreactive varicose fibers has been detected in the rat olfactory nerve layer and glomerular layer of the olfactory bulb (OB). An important group of perykarya and thin varicose fibers has been observed in the olfactory tubercle. We have demonstrated the presence of both ANP precursor and ANP gene transcript in the rat olfactory bulb. In addition to synthesizing ANP, the OB contains ANP transducing receptors coupled to guanylyl-cyclase system. The immunoreactive ANP has also been detected in the rat olfactory mucosa (OM), where ANP has been localized in secretory cells of Bowman's gland and in the cells of the epithelial layer. The relatively low concentration of ANP in OM (2.5 ng/mg protein) suggests a local role for ANP, a hypothesis which is strengthened by the presence of ANP high affinity receptors in this tissue. Although the role of ANP in the olfactory system is not yet clear, ANP has been shown to modulate olfactory bulb mitochondrial membrane activity and to be involved in the olfactive function.