The protective effects of different treatments on rat salivary glands after radiotherapy

Effect of hyperbaric oxygen treatment on ischaemia-reperfusion injury in rats detorsioned after experimental ovarian torsion

Introduction

This study aimed to investigate whether hyperbaric oxygen treatment (HBOT) could ameliorate ischaemia-reperfusion injury in a rat model of ovarian torsion-detorsion.

Methods

Twenty-seven rats were divided among four groups: surgical sham rats (S) (n = 6) underwent identical anaesthesia and surgical incisions to other groups (n = 7 per group) but with no ovary intervention; torsion rats (T) underwent laparotomy, ovarian torsion, relaparotomy and sacrifice after three hours; torsion and detorsion rats (T/DT) underwent laparotomy, ovarian torsion (three hours), relaparotomy and detorsion, and sacrifice after one week; torsion, detorsion, hyperbaric oxygen rats (T/DT/HBOT) underwent laparotomy, ovarian torsion, relaparotomy and detorsion, and sacrifice after one week during which HBOT was provided 21 times (100% oxygen at 600 kPa for 50 min). In all groups blood collection for markers of oxidative stress or related responses, and ovary collection for histology were performed after sacrifice.

Results

When the T/DT, and T/DT/HBOT groups were compared, 8-hydroxy-2'-deoxyguanosine (a marker of oxidative damage to DNA) and malondialdehyde (a product of lipid peroxidation) levels were lower in the T/DT/HBOT group. Anti-Mullerian hormone levels were higher in the T/DT/HBOT group compared to the T/DT group. In addition, oedema, vascular occlusion, neutrophilic infiltration and follicular cell damage were less in the T/DT/HBOT group than in the T/DT group.

Conclusions

When biochemical and histopathological findings were evaluated together, HBOT appeared reduce ovarian ischaemia / reperfusion injury in this rat model of ovarian torsion-detorsion.

Radiobiological comparison of flattening filter (FF) and flattening filter-free (FFF) beam in rat laryngeal tissue

PURPOSE

The purpose of this study is to investigate the radioprotective effect of melatonin by analyzing histopathological changes and serum biochemical levels on experimental rat models exposed to flattening filter (FF) and flattening filter-free (FFF) beam.

MATERIALS AND METHODS

Forty-eight healthy adult Sprague Dawley rats were randomly divided into six groups. The control (Group 1) was given no treatment, the melatonin (Group 2) was given 10 mg/kg melatonin only, the FF (Group 3) and FFF (Group 5) were given fractionated dose (Total 32 Gy, 5 consecutive days) radiotherapy only, and the FF plus melatonin (Group 4) and FFF plus melatonin (Group 6) were given 10 mg/kg melatonin 15 minutes prior to irradiation. Rats were examined for histopathology and biochemical analysis 10 days after irradiation.

RESULTS

When results of FF and FFF radiotherapy only groups are compared to control group, statistically significant difference in histopathological and biochemical parameters are observed; however, melatonin administration in radiotherapy plus melatonin groups improved these parameters (p <.05). In addition, there was no statistically significant difference between FF and FFF beams (p > .05).

CONCLUSIONS

The effect of low- and high-dose beams on the rat larynx and serum samples were investigated histopathologically and biochemically for the first time. We observed that melatonin supplemented before FF and FFF radiotherapy protected early period radiotherapy-induced laryngeal mucosal damage. Since the radiobiological results of FF and FFF beams are similar, FFF beams can be safely applied in laryngeal irradiation. However, more experimental rat and clinical studies are needed to clarify the radiobiological uncertainy concerning dose rate on cancerous and healthy tissue.

Experimental Animal Model Systems for Understanding Salivary Secretory Disorders

Salivary secretory disorders are life-disrupting pathologic conditions with a high prevalence, especially in the geriatric population. Both patients and clinicians frequently feel helpless and get frustrated by the currently available therapeutic strategies, which consist mainly of palliative managements. Accordingly, to unravel the underlying mechanisms and to develop effective and curative strategies, several animal models have been developed and introduced. Experimental findings from these models have contributed to answer biological and biomedical questions. This review aims to provide various methodological considerations used for the examination of pathological fundamentals in salivary disorders using animal models and to summarize the obtained findings. The information provided in this review could provide plausible solutions for overcoming salivary disorders and also suggest purpose-specific experimental animal systems.

Protective Effect of Whortleberry Extract on Salivary Gland Damage Induced by Neck Irradiation in Rats

Radiotherapy is a method of treatment used on malignant head and neck tumors; however, it may lead to adverse effects by influencing other tissues because its effects are not specific to tumor tissues. These adverse effects limit the effectiveness of the treatment and sometimes lead to termination of the treatment. This study aims to histopathologically and biochemically investigate the protective effect of whortleberry against the cellular degeneration and oxidative stress that take place in salivary glands due to radiotherapy. The rats were divided into 6 groups. One group was given radiotherapy only, one group was given radiotherapy and 100 mg/kg of whortleberry, and one group was given radiotherapy and 200 mg/kg of whortleberry. The remaining 3 groups were designated as whortleberry, sham, and control groups. At the end of the study, samples collected were histopathologically and biochemically analyzed. In the group given radiotherapy only, acinar areas were reduced histopathologically, whereas ductal areas increased (P < .01). Oxidative stress increased only in the group given radiotherapy, whereas the oxidative stress levels in the other groups were close to those in the control groups. In conclusion, whortleberry reduces cellular degeneration and oxidative stress that take place in salivary glands due to radiotherapy.

5-Fluorouracil induces inflammation and oxidative stress in the major salivary glands affecting salivary flow and saliva composition

This study aimed to elucidate the effect of 5-fluorouracil (5-FU) on the histological aspects of the major salivary glands, salivary flow and saliva composition using an established oral mucositis model in hamsters. Oral mucositis was induced by two intraperitoneal administrations of 5-FU in two consecutive days (60 and 40mg/kg), followed by cheek pouch mucosa scratch, on day 4. The Pilocarpine-stimulated salivary flow was measured 4 and 10days after the first 5-FU injection. Salivary glands were harvested for histopathological analysis, measurement of inflammatory cells, quantification of pro-inflammatory cytokines (TNF-α and IL-1β), investigation of cell death and cell proliferation. Oxidative stress and oxidative defense system were also investigated in the salivary gland tissues using MDA (malondialdehyde), nitrite, non-protein sulfhydryl groups (NP-SH), SOD (superoxide dismutase) and CAT (catalase). In addition, the CAT and lysozyme activities and the IgA and SOD levels were evaluated in the saliva samples. 5-FU significantly reduced the pilocarpine-stimulated salivary flow rate on the 4th experimental day, associated with an increase in the SOD levels in saliva. Recovery of the salivary flow and SOD were observed on day 10, when an increase in the saliva lysozyme levels was detected. In addition, 5-FU promoted vacuolization in parotid (P) and periductal edema in submandibular (SM) gland, combined with an increase in the inflammatory cells influx, mostly observed on the 4th day in SM gland and on 4th and 10th days in P. Oxidative stress was found mostly on day 10 in SM, SL and P glands, associated with release of proinflammatory cytokines, observed in SM and SL glands, but not in P. 5-FU induces an inflammatory response in the major salivary glands, most observed ten days after its first injection, which may contribute to the major salivary glands hypofunction, leading to alterations in the salivary flow rate and composition.