Effect of formaldehyde inhalation on rabbit nasal mucosa: a light microscopic study—an animal model for inhalational irritants on nasal mucosa

Background Formaldehyde is associated with many adverse health effects and is classified as a human carcinogen. Formaldehyde is highly water-soluble and readily absorbed and metabolized by the respiratory mucosa upon inhalation. The histopathological effects of formaldehyde on the nasal mucosa and olfactory nerves in adult New Zealand white rabbits were studied to validate this animal model of inhalational irritants. Results Compared to control group 1 (exposed to air), groups 2 and 3 (exposed to formaldehyde for 90 min and 210 min, respectively) exhibited disrupted nasal tissue, ulcerated epithelial coverings, markedly dilated blood vessels, and increased numbers of inflammatory cells in the lamina propria. The olfactory neuro-epithelium exhibited a reduction in the number of cilia. Many sustentacular cells lost their microvilli. Olfactory nerves exhibited nerve bundle shrinkage within the perineural sheath, leaving an empty space with evidence of edema within the nerve fibers. Conclusion Formaldehyde inhalation has destructive effects on the nasal mucosa and olfactory nerves in adult New Zealand white rabbits. These results validate the use of this animal model to assess the effects of inhalational irritants on the nasal mucosa.

HISTOLOGICAL EFFECTS OF FORMALDEHYDE INHALATION ON THE ALVEOLAR ARCHITECTURE OF LUNGS OF ALBINO RATS

Introduction: Formaldehyde is a flammable, colourless, reactive, readily polymerized gas at normal room temperature and pressure. Formaldehyde vapour is readily absorbed from the lungs. Formaldehyde is combined with methanol and buffers to make embalming fluid. In the dissection hall, during embalming or cadaveric dissection and histo-pathological preservation, medical professionals are exposed to formaldehyde vapours. Respiratory system is the major target of formaldehyde. So, the present study aims to assess the histological changes on the architecture of alveoli of albino rats after inhalation of formaldehyde vapours. Material & Methods: 24 albino rats were exposed to formaldehyde vapours for 28 days. They were exposed with various concentrations and thus 4 groups, having 6 rats in each, were made. They were sacrificed and the lung tissue was taken and studied by using H & E stain. Results: The study shows a number of important histological changes which are concentration dependent. Conclusion: It may be concluded from the present study that concentration of formaldehyde can affect significantly on the histopathology of the lungs of albino rats.

THYMUS VARIABILITY IN WHITE RATS EXPOSED TO FORMALDEHYDE

The aim of the paper is to study thymus variability in white rats, which were exposed to formaldehyde, and to compare these data with the indicators in control animals. Materials and Methods. The trial enrolled 72 white male rats, initial body weight 40–50 g. The animals were divided into 2 groups (36 rats in each). The first group consisted of control rats. Animals of the second group were exposed to formaldehyde inhalation, 2.766 mg/m3. To characterize the variability of the organ size, centroids were determined. The superposition of landmark configurations was performed using the generalized Procrustes analysis method, MorphoJ 1.06d program. The principal component analysis and canonical analysis of the obtained data were carried out. Results. One-Way ANOVA revealed a high level of intergroup differences in Procrust distance (F=1.34; p<0.0001). The significant effect of the duration of formaldehyde exposure on centroid size was established. The Kruskal-Wallis criterion was 19.778 (p=0.0014). The analysis of the principal components indicated that each of the first 10 components stands for more than 1 % of Procrustes coordinate variance. In this case, the first 7 components compatibly explain 91.398 % of thymus variability. The proportion of the first main component to the total variance of the Procrustes coordinates is 40.236 %. PC1 (-) shows changes in the thymus shape, mostly affecting the tops of its lobes, the middle part of the right boundary and the entire left thymus boundary. The scattering ellipses of the thymus ordinates in rats exposed to formaldehyde, in the first two canonical variables are located higher than those in the control animals. Conclusion. Formaldehyde inhalation leads to thymus changes in white rat. The most significant differences with control data are determined along the second canonical variable. Keywords: thymus, form, rat, formaldehyde, geometric morphometry. Цель. Изучение изменчивости формы тимуса белых крыс, находившихся в условиях влияния формальдегида, и сравнение этих данных с показателями, полученными у контрольных животных. Материалы и методы. Работа выполнена на 72 белых крысах-самцах с начальной массой тела 40–50 г. Животные были разделены на 2 серии (по 36 крыс). Первую серию составляли контрольные крысы. Животные второй серии подвергались ингаляционному воздействию формальдегида (ФА) в концентрации 2,766 мг/м3. Для характеристики изменчивости размеров органов определяли размер их центроидов. Процедуру суперимпозиции конфигураций ландмарок выполняли методом генерализованного прокрустова анализа с использованием программы MorphoJ 1.06d. Проводили анализ главных компонент и канонический анализ полученных данных. Результаты. Однофакторный дисперсионный анализ выявил высокий уровень межгрупповых различий по показателю прокрустовых расстояний (F=1,34; р<0,0001). Установлено значительное влияние продолжительности нахождения животных в условиях воздействия ФА на размер центроида. Критерий Краскела–Уоллиса составил 19,778 (р=0,0014). Анализ главных компонент указывал на то, что каждая из первых 10 компонент объясняет более 1 % дисперсии прокрустовых координат. При этом первые 7 компонент совместно объясняют 91,398 % изменчивости формы тимуса. Вклад первой главной компоненты в общую дисперсию прокрустовых координат составляет 40,236 %. РС1 (–) показывает изменения формы тимуса, в большей степени затрагивающие верхушки его долей, среднюю часть правого контура и весь левый контур тимуса. Эллипсы рассеивания ординат тимусов, принадлежащих крысам, подвергавшимся влиянию ФА, в пространстве первых двух канонических переменных расположены выше по отношению к таковым контрольных животных. Заключение. Ингаляционное воздействие формальдегида приводит к изменению формы тимуса белых крыс. Наибольшие различия с контрольными данными определяются вдоль второй канонической переменной. Ключевые слова: тимус, форма, крыса, формальдегид, геометрическая морфометрия.

Curcumin Prevents Renal Dysfunction, Proteinaceous and Granular Cast Formation in Tubular Lumen in Kidney of Mice Exposed to Formaldehyde Inhalation

Formaldehyde is a volatile chemical compound that is commonly used in the chemical industry. Formaldehyde inhalation exposure has been associated with cancer, respiratory diseases, digestive and neurological disorders. Oxidative stress is one of the potential mechanisms by which formaldehyde inhalation induces toxicity. Curcumin is a natural compound endowed with antioxidant properties and my thus prevent formaldehyde-induced toxicity. This study aimed to examine the effects of formaldehyde inhalation on renal function and kidney structure of mice; the potential protective effects of curcumin administration against kidney dysfunction, renal damage and oxidative stress were also investigated. Formaldehyde inhalation induced renal dysfunction and damage, as shown by the increase of serum creatinine and blood urea nitrogen levels, and caused histological damage associated with proteinaceous and granular cast formation in renal tubular lumen. The activity of antioxidant enzymes remained unchanged and malondialdehyde levels increased in a discrete and statistically non-significant way. Curcumin treatment prevented the above-described alterations by preventing an increase in renal dysfunction and changes in the kidney structure of mice. Therefore, curcumin can be a potentially useful treatment against the effects induced by exposure to gaseous pollutants such as formaldehyde in distal organs.