Tania Tavares Rodriguez

Prolactin secretion in hypothyroid endotoxemic rats: involvement of L-arginine and nitric oxide synthase.

The identification of nitric oxide (NO) within the hypothalamus and pituitary gland has suggested its role as modulator of the activity on hypothalamic-pituitary axis. Hypothalamic NO synthase (NOS) is known to be regulated by thyroid hormones. We investigated the effects of previous injection of Nϖ-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, and L-arginine (L-Arg), the substrate for NO synthesis, on prolactin (PRL) secretion, through the lipopolysaccharide (LPS)-induced inflammatory response in thyroidectomized (TX) rats. TX or sham-operated (N) rats were intraperitoneally (i.p.) injected with L-NAME (10 mg kg-1) or L-Arg (200 mg kg-1) or the same volume of vehicle (saline solution) 30 min before endotoxemia-induction with LPS at 250 μg (100 g body weight)-1, i.p.. In N rats, NO increased PRL release in response to endotoxemia, whereas in hypothyroid rats, NO appeared to have the opposite effect. Our data support the hypothesis that NO exerts a modulatory influence on PRL secretion after LPS-induced inflammatory response.

The effect of phototherapies on bone repair of euthyroid and hypothyroid rats: Raman spectroscopic study

The repair of bone tissue is complex and can be influenced by several local and systemic factors that can delay the repair. Laser and LED phototherapies have shown positive results in the repair of bone tissue. The aim of this study was to evaluate, through Raman spectroscopy, the influence of laser (λ780 nm) and LED (λ850 nm) phototherapies in the repair of surgical defects in femurs of euthyroid and hypothyroid rats. Thirty Albinus Wistar rats were randomly divided into 6 groups. The animals of the hypothyroid groups were submitted to surgical removal of the thyroid gland. After general anesthesia, a surgical bone defect was created in the femur of each animal and filled with blood clot in all groups. In group I (Euthyroid) the defect was created in euthyroid animals; In Group II (Hypo) the defect was created in hypothyroid animals; In Group III (Euthyroid Laser) the defect was irradiated with Laser; on Group IV (Hypo Laser) the defect was made in a hypothyroid animal and irradiated with Laser; on Group V (Euthyroid LED) the defect was irradiated with LED and on Group VI (Hypo LED) the defect was created in hypothyroid animals and LED irradiated. Irradiation was carried out at every 48-h for 15 days. Specimens were taken and stored in liquid nitrogen. Intensity of peaks of phosphate HA (~960 cm-1), carbonated HA (~1,070 cm-1) and collagen (~1,414 cm-1) were measured by Raman Spectroscopy. The results showed that the health status had significant influence all peaks. Irradiation influenced only the peak of ~1454 cm-1. It is concluded that phototherapies influences bone repair in cases of thyroid diseases.

Evaluation of phototherapy in the differentiation of mesenchymal stem cells in the tissue repair of rats submitted to a hyperlipidemic diet

Obese people present a greater risk of developing other systemic diseases and comorbidities such as compromising the tissue repair process. Laser phototherapy can contribute to this repair by improving cellular functions, since stem cells may play an important role in repair due to their pluripotent potential. In this way, the influence of Laser Phototherapy (LP) was evaluated in the tissue repair of rats submitted to a hyperlipid diet through CD49 immunostaining for adipose stem cells. Forty-eight Wistar albinus rats were divided into two experimental groups: Standard Diet (SD) and Hyperlipid Diet (HD) for 20 weeks. After this period, excisional dorsal cutaneous wounds of 1 cm2 were made. The groups were subdivided into control and laser, the laser groups were irradiated (Diode Laser of Gallium and Aluminum Arsenide, λ660nm, 40mW, 6J / cm2) immediately after the surgery and every 48 hours. A group of rats were killed on day 7 and the other group on day 14 and the specimens processed by the immunohistochemical technique. The SD group presented antibodies marked with moderate to intense intensity, whereas in the HD group the weak staining for the time of 14 days prevailed. The irradiation protocol employed had no influence on the CD49 marker when compared to the control and irradiated groups over the same period. According to the methodology used and the results obtained it is concluded that laser light does not influence the recruitment of adipoderivative stem cells for the tissue repair process.

Does laser phototherapy influence the proliferation of myoepithelial cells in the salivary gland of hypothyroid rats

Thyroid hormones influence both development and growth of organs and tissues and guarantee metabolic demands that interfere with the quality of digestive secretions, including those of the salivary glands. Laser phototherapy - LPT can modulate various biological phenomena and its diverse effects permit the action on different cell types. The aim of this study was to evaluate the influence of laser phototherapy on myoepithelial cells of salivary glands of hypothyroid rats. Forty-two albino Wistar rats were divided into two main groups: euthyroid (EU) and hypothyroid (HYPO). Hypothyroidism was induced using propylthiouracil (PTU) for 4weeks. Each group was divided into subgroups: control (without laser) and laser groups (Red/infrared - IR). LPT was used on the submandibular gland and was carried out using a diode laser (λ660 or λ780nm, 40mW, spot size 0.04cm2, irradiation area 1cm2, 300s, 6J/cm2 per gland, 12J/cm2 per session) and started two weeks after PTU treatment. LPT was repeated every other day for two weeks. After animal death, the glands were removed, dissected and processed for immunohistochemical analysis. It was observed an increase in the number of myoepithelial cells of hypothyroid control rats in comparison to euthyroid controls (p=0.001). Visible LPT (λ660nm) caused significant higher proliferation of myoepithelial cells in EU rats when compared to IR LPT (λ 780nm)(p≤0.001).It is concluded that, despite the LPT protocol used did not influence myoepithelial proliferation on hypothyroid rats it significantly increased the proliferation on euthyroid animals.