Early effect of laser irradiation in signaling pathways of diabetic rat submandibular salivary glands.

Low-power laser irradiation (LPLI) is clinically used to modulate inflammation, proliferation and apoptosis. However, its molecular mechanisms are still not fully understood. This study aimed to describe the effects of LPLI upon inflammatory, apoptotic and proliferation markers in submandibular salivary glands (SMGs) in an experimental model of chronic disorder, 24h after one time irradiation. Diabetes was induced in rats by the injection of streptozotocin. After 29 days, these animals were treated with LPLI in the SMG area, and euthanized 24h after this irradiation. Treatment with LPLI significantly decreased diabetes-induced high mobility group box 1 (HMGB1) and tumor necrosis factor alpha (TNF-α) expression, while enhancing the activation of the transcriptional factor cAMP response element binding (CREB) protein. LPLI also reduced the expression of bax, a mitochondrial apoptotic marker, favoring the cell survival. These findings suggest that LPLI can hamper the state of chronic inflammation and favor homeostasis in diabetic rats SMGs.

The Effects of Low-Power Laser Irradiation on Inflammation and Apoptosis in Submandibular Glands of Diabetes-Induced Rats.

Diabetes can lead to dysfunction of the secretory capacity in salivary glands. Activation of the receptor for advanced glycation end products (RAGE) and its ligands has been suggested to participate in chronic disorders such as diabetes and its complications. In this study, the expression of RAGE, high mobility group box 1 (HMGB1) and advanced glycation end products (AGE), as well as the effects of low-power laser irradiation (LPLI) in salivary glands of diabetic rats were evaluated, and the mechanisms involved were characterized. The expression of RAGE and HMGB1 at the protein and mRNA levels was observed in submandibular glands (SMGs) of streptozotocin-induced diabetic rats. A diode laser was applied at 660 nm, 70 mW, 20 J/cm2, 0.56 J/point, with a spot area of 0.028 cm2 and its in vivo effects and the pathways involved were evaluated. Immunohistochemistry and western blotting analysis were performed for inflammatory and apoptosis markers. Diabetes up-regulates HMGB1/AGE/RAGE axis gene expression in SMGs that is associated with activation of the nuclear factor kappa B (NF-κB) pathway. Interestingly, LPLI suppresses NF-κB activation induced by inflammation. LPLI also reduces diabetes-induced apoptosis. That effect was accompanied by decreased levels of Bax, and cleaved caspase 3, which were up-regulated in diabetes. Taken together, our data suggest that LPLI reduces diabetes-induced inflammation by reducing the induction of HMGB1, ultimately leading to inhibition of apoptosis in submandibular glands of diabetic rats.

Impact of intraoral stent on the side effects of radiotherapy for oral cancer.

BACKGROUND: The intraoral stent is a mouth-opening device which may be used during head and neck cancer radiotherapy with the intention of preventing unnecessary irradiation in normal adjacent tissue. The use of this device during intensity-modulated radiation therapy (IMRT) has not been reported in the literature. METHODS: A 30-year-old woman with squamous cell carcinoma of the tongue was submitted to a CT for IMRT treatment planning with and without the use of the intraoral stent. RESULTS: Dosimetric analysis showed that the irradiation dose to the maxilla, both parotid glands, and left submandibular gland decreased with the use of this device. CONCLUSION: This article shows that intraoral stents seem to be useful in decreasing the radiation dose to healthy structures, especially in bone structures and salivary glands during radiotherapy, and emphasizes the importance of a multidisciplinary team during oncological therapy.

Radioprotection of sensitive rat tissues by oligoelements Se, Zn, Mn plus Lachesis muta venom.

In this study we first evaluated the general radioprotective efficacy of Se, Zn and Mn (4 µg/ml each) plus Lachesis muta venom (4 ng/ml) combination (O-LM) by determining survival on rats irradiated with lethal doses of gamma-rays. The aim of the second part of the study was to investigate the O-LM ability to prevent ionizing radiation-induced damage on small intestine, bone marrow and submandibular glands. Hence, histological characteristics and functional studies, together with proliferation and apoptotic marker levels on whole body irradiated rats with a 5 Gy dose were evaluated. Results show that all animals of the untreated group died after whole body irradiation with 8 and 10 Gy while 60 day-survival was more than 80% and 40% in O-LM-treated animals, respectively. Histopathological examinations revealed a high degree of small intestine and submandibular gland radioprotection 3 days post-irradiation. O-LM inhibited histological damage on small intestine, restoring the radiation-induced reduction in villous height and crypt number. O-LM prevented radiation-induced loss of salivary gland function and morphological alterations. These effects were associated to a complete inhibition of radiation-induced apoptosis. Furthermore, studies performed 30 days post-irradiation revealed that O-LM significantly improved bone marrow repopulation, increasing all medullar progenies to the extent of the non-irradiated animals, and completely prevented permanent submandibular gland alterations. Based on the present results and taking into account that O-LM is being safely administered in phase I clinical trial as an immunomodulator, we conclude that O-LM is a non-toxic promising approach to achieve radioprotection for patients undergoing radiotherapy.

Histamine prevents functional and morphological alterations of submandibular glands induced by ionising radiation.

PURPOSE: Xerostomia is a common, disturbing side-effect among patients treated with radiotherapy for head-and-neck cancer. The aim of the present work was to investigate whether histamine could prevent salivary gland dysfunction and histological alterations exerted by ionising radiation. MATERIALS AND METHODS: Forty-eight rats were divided into four groups. Histamine and histamine-5 Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 24 h before irradiation. Histamine-5 Gy and untreated-5 Gy groups were irradiated with a single dose of whole-body Cesium-137 irradiation. Control and untreated-5 Gy groups were given daily saline injections. Three days post irradiation metacholine-induced salivary secretion was measured or animals were sacrificed and submandibular gland (SMG) removed, stained and histological characteristics were evaluated. Proliferation and apoptosis markers were studied by immunohistochemistry. RESULTS: Radiation decreased salivary secretion by 40% in comparison to untreated rats, which was associated with loss of SMG mass, alteration of epithelial architecture, partial loss of secretor granular material, diminished proliferation and a remarkable apoptotic response. In contrast, histamine completely reversed the reduced salivation induced by radiation, conserved glandular mass with normal appearance and preserved the structural organisation of secretor granules. Radiation-induced toxicity is prevented by histamine essentially by suppressing apoptosis of ductal and acinar cells, reducing the number of apoptotic cells per field (19.0 ± 3.8 vs. 106.0 ± 12.0 in untreated animals, P < 0.001), and also by preventing the radiation-induced decrease in cell proliferation. CONCLUSIONS: Histamine prevents morphological and functional radiation-induced damage on SMG, representing a potential radioprotector for treatment of patients undergoing radiotherapy for head and neck malignancies.

Diode laser decreases the activity of catalase on submandibular glands of diabetic rats.

OBJECTIVE: The aim of this study was to evaluate the effect of laser irradiation on the amylase and the antioxidant enzyme activities, as well as on the total protein concentration of submandibular glands (SMG) of diabetic and non-diabetic rats. BACKGROUND: Laser has been used aiming to improve some biochemical alterations observed in salivary glands of streptozotocin-induced diabetic rats. MATERIALS AND METHODS: Ninety-six female rats were divided into eight groups: D0, D5, D10, and D20 (diabetic animals), and C0, C5, C10, and C20 (non-diabetic animals), respectively. Diabetes was induced by administering streptozotocin and confirmed later by the glycemia results. Twenty-nine days after diabetes induction, the SMG of groups D5 and C5, D10 and C10, and D20 and C20 were irradiated with 5, 10, and 20 J/cm(2), respectively. A diode laser (660 nm/100 mW) was used. On the day after irradiation, the rats were euthanized and the SMG were removed. Catalase, peroxidase, and amylase activities, as well as protein concentration, were assayed. RESULTS: Diabetic rats without irradiation (D0) showed higher catalase activity (p < 0.05) when compared to C0 (0.16 +/- 0.05 and 0.07 +/- 0.01 U/mg protein, respectively). However, laser irradiation of 5, 10, and 20 J/cm(2) reduced the catalase activity of diabetic groups (D5 and D20) to non-diabetic values (p > 0.05). CONCLUSION: Based on the results of this study, laser irradiation decreased catalase activity in diabetic rats' SMG.

Decrease in salivary secretion by radiation mediated by nitric oxide and prostaglandins.

OBJECTIVE: In the present work, we evaluated the effect of exposing the submandibular glands (SMG) to radiation, studying different functional parameters such as salivary secretion, nitric oxide (NO) production, reactive oxygen species formation, prostaglandin (PGE) content and apoptosis. METHODS: We irradiated rats in the head and neck region with a single dose of gamma-ray radiation of 15 Gy. Two hours after radiation, we measured norepinephrine-induced salivary secretion. After that, the SMG were dissected, and in this tissue, we measured the activity of NO synthase (NOS), the PGE content, the amount of reactive oxygen species, apoptotic cells and mitochondrial inducible NOS (iNOS) expression. RESULTS: We found that radiation decreased salivary secretion when 10 and 30 microg/kg of norepinephrine was administered via the right femoral vein. We observed that iNOS activity was reduced and PGE content increased after radiation in SMG, indicating that NO and PGEs may participate in salivary secretion. The expression of mitochondrial NOS was increased after radiation leading to the formation of large amounts of NO that acts as a proapoptotic signal. In fact, we observed an augmentation in apoptotic cells. In this study, we also observed an increase in lipid peroxidation induced by radiation that may contribute to tissue damage. CONCLUSIONS: Our results indicate that radiation induced a decrease in salivary secretion and SMG iNOS activity, meanwhile the PGE content, the lipid peroxidation and apoptosis increased in the tissue. These modifications decrease salivary secretion.

Effect of low-power radiation (helium/neon) upon submandibulary glands.

OBJECTIVE: The aim of this work was to study the effect of low-power laser radiation on guinea pig salivary glands. BACKGROUND DATA: Low-power laser radiation changes some cellular functions. The effect on salivary glands has not been sufficiently studied. MATERIALS AND METHODS: One hundred and forty-four male guinea pigs (150 +/- 30 g body weight) were used. The animals were divided into two groups: control group (fed animals and those undergoing 2, 4, 8, 10, and 12 h of fasting) and experimental group (irradiated). Both the right and left submandibular glands were later irradiated with helium-neon laser at 7-mW power, with a 0.75-mm spot, under continuous pulse for 2 min in a one-session exposure; a 11.2 J/cm(2) energy density was applied. Then, the irradiated animals were fed, or underwent 2, 4, 8, 10 and 12 h of fasting. Samples of submandibular glands were taken with a punch (5 mm diameter) and were used for optic and transmission electron microscopy studies. RESULTS: The structural observations showed that the irradiation effect was progressive; and showed a trophic stimulant effect at 2 h following irradiation, with vasodilatation, vascular congestion, perivascular infiltrate, and a necrotic picture of glandular parenchyma at longer times. The ultrastructural observations showed alterations of rough endoplasmic reticulum. CONCLUSION: We propose that low-power laser radiation with the doses applied in this study disturbs protein synthesis and secretion of guinea pig submandibulary glands.

Efeitos da radiaçäo eletromagnética na glândula submandibular de fetos de rato / Effects of radiofrequency radiation on submandibular gland of rat foetus

A radiaçäo eletromagnética (REM) na faixa de rádio-frequência (rf) que ocupa de 300 KHz a 300 MHz é utilizada atualmente para inúmeros fins industriais, médicos e científicos. A REM ao interagir com materiais biológicos pode ser transmitida, absorvida e refletida em vários graus, podendo resultar tanto em efeitos benéficos medicinais quanto em danos biológicos. Esse trabalho teve o objetivo de estudar morfometricamente os possíveis efeitos da radiofrequência e de gradientes de campos magnéticos em glândulas submandibulares de fetos de ratos. Para tal, foram irradiadas fêmeas com rf de 20 MHz, 7,4 mW de potência e SAR=30 mW/kg (Specific Absortion Rate), durante 10 minutos diários, até o 20§ dia de gestaçäo, após o qual foram sacrificadas. Seus fetos foram retirados e processados para análise em microscópio de luz. Foram feitas avaliaçöes morfométricas da densidade de volume, volume absoluto e relaçäo núcleo-citoplasma das células de túbulos terminais, vasos sanguíneos e tecido conjuntivo da glândula submandibular. A comparaçäo dos resultados pela análise de variância demonstrou ocorrer um significativo aumento da densidade de volume e volume absoluto nuclear e citoplasmático das células dos túbulos terminais do grupo irradiado em relaçäo ao controle. Em relaçäo as células de ductos näo houve diferença estatística significante. A densidade de volume de tecido conjuntivo foi maior no controle. Em base a esses dados é possível pressupor que radiaçöes eletromagnéticas mesmo as de baixa intensidade podem promover alteraçöes volumétricas de células dos túbulos terminais

Modification of the beta-adrenergic sensitivity of rat submandibular gland by constant light.

Rats exposed for 2, 5, 10, 20, 35 and 50 days to constant light (CL) showed beta-adrenergic desensitization of the submandibular gland as indicated by dose-response curves to 1.5, 2.0, 3.0, 10.0, 30.0 and 50.0 micrograms/kg isoproterenol. The phenomenon, evident with 1.5, 2.0 and 50.0 micrograms/kg after 2 days at CL, was more intense as time of exposure increased to reach values of about 50% those for controls after 20 days. After 35 and 50 days, desensitization showed some reversion, but the secretory responses were still lower than for controls maintained under a typical photoperiod. In the groups of rats exposed to CL for 20 days, gland wet and dry weights were higher (10%) than those of controls. These changes probably indicate an adaptation of the sympathetic control of salivary secretion induced by environmental illumination.

Effect of chronic constant light on sensitivity of rat submandibular gland.

A consistent difference in the secretory response between submandibular (SM) glands of rats maintained under constant light (CL) during 50 days and those of rats under a photoperiod (14 h light: 10 h dark) was found. We have used alpha 1-adrenergic, muscarinic, peptidergic and beta-adrenergic secretagogue agents to study the secretory response of rat SM glands "in vivo". The response to phenylephrine, methacholine and substance P, was increased by exposure CL, while that to isoproterenol was diminished. The changes in the sensitivity of the secretory response from SM gland of rats under CL might be related to changes in the normal interplay of various receptors as well as to possible alteration in the intracellular signal transduction. It may represent and adaptive process of the nervous control of saliva secretion by environmental light and be of physiological and clinical interest.

Açäo direta da radiaçäo X sobre as glândulas submandibulares e sublinguais: estudo histológico e histoquímico em ratos / Direct action of the X-ray on the submandibular and sublingual glands: histologic and histochemistry study in rats

Foi propósito deste trabalho analisar o efeito direto dos raios X sobre as glândulas submandibular e sublingual expostas cirurgicamente e irradiadas após serem isoladas com lâmina de chumbo das estruturas adjacentes. Foi realizado um grupo simulado no qual as glândulas submandibular e sublingual foram apenas expostas cirurgicamente. As glândulas dos grupos-controle e simulado mostraram aspectos normais ao estudo histológico e histoquímico. As glândulas irradiadas apresentaram atrofia, desarranjo arquitetural e processos degenerativos no citoplasma e núcleo das células dos ácinos. Os núcleos das células dos ductos granulosos, esfriados e excretores apresentaram processos degenerativos como picnose, cariorrexis e/ou cromatólise. Houve reduçäo do RNA dos núcleos, nucléolos e citoplasma das células dos ácinos; ausência ou diminuiçäo de glicogênio nos citoplasmas das células dos ductos estriados e reduçäo da síntese de proteínas