Tehran University Medical Journal

Background: Evaluation of cell viability is momentous in pharmacologic and oncological research. Cell viability evaluation determines cell sensitivity and consequently treatment outcome. Various methods are available to determine cell survival. Each of these methods evaluates different endpoints. Accordingly, determining the correlation between these methods is important. In this study, in order to determine the viability of human anaplastic thyroid cancer cell line, the sensitivity of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, trypan blue test and clonogenic assay were compared.
Methods: This experimental study was performed in the Cellular and Molecular Research Center at Guilan University of Medical Sciences, Rasht, Iran from October 2016 to March 2017. The human anaplastic thyroid cancer cell line was cultured in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS). The cultured cells were treated with melatonin, for 24 hours. Then, the viability of the cells was evaluated by MTT assay, trypan blue test and clonogenic assay. Furthermore, plating efficiency and surviving fraction were used in order to draw survival curve in the clonogenic assay.
Results: The concentration of melatonin at IC50 point was 4.794±0.117 millimolar (mM) in MTT assay, 4.375±0.894 mM in trypan blue test and 2.246±0.326 mM in clonogenic assay. Comparing the IC50 values of these test revealed that C50 values obtained from MTT assay and trypan blue test had no significant difference (P=0.6446), while there was a significant difference between IC50 values obtained from MTT and clonogenic assays (P=0.0032). Moreover, the IC50 values obtained from trypan blue test and clonogenic assay were also significantly different (P=0.0078). The results of the regression analysis of cell viability were shown a linear, positive and significant correlation between these three methods and MTT assay and trypan blue test showed higher correlation (r=0.99, P<0.001).
Conclusion: Based on our results, all these methods were effective to identify cytotoxicity in human anaplastic thyroid cancer cell line, while MTT assay and trypan blue test were more sensitive than clonogenic assay.

Background: Animals have an internal biological clock with melatonin hormone that helps them to adapt to light/dark circles. Since melatonin is associated with an alteration in the expression and production of opioid receptors, this study aimed to evaluate the effect of changes in the light/dark circles on pain sensation in rats.
Methods: This research study in order to investigate the thermal and chemical pain sensation using tail flick and formalin tests, 35 Wistar rats were randomly divided into five groups of seven animals, including 24 hours of light (24L), 16 hours of light / 8 hours of darkness (16L/8D), 12 hours of light / 12 hours of darkness (control), 8 hours of light / 16 hours of darkness (8L/16D) and 24 hours of darkness (24D) were tested. The study was conducted at the Department of Biology of Ferdowsi University of Mashhad, Iran, from April to September 2015. Also besides the Rotarod test was performed to determine the general motor activity of animals.
Results: In the tail flick test, an increase in the time of darkness elevated the threshold of thermal pain and subsequently resulted in analgesic effect in the 24 hours of darkness (24D) group (P=0.03), while reducing the dark period in the group of 16 hours of brightness / 8 hours of darkness caused a reduction in the threshold of thermal pain, resulting in hyperalgesia (P=0.002). In the formalin test, the chemical pain score at the end of the chronic phase was significantly increased in the experimental group of 16 hours of brightness / 8 hours of darkness compared to control, indicating hyperalgesia (P=0.03).
Conclusion: Perhaps, alterations in light duration may change the production of melatonin and opioids and their receptors. Therefore, it is expected that reduction of the duration of darkness and thus shortening the period of increased production of melatonin and the subsequent lower expression of opioid receptors, in this group, resulting in a lower thermal pain threshold and analgesic response.

Background: Melatonin is one of the drugs which are used in the treatment of sleep problems, including insomnia and sleep deprivation. The aim of the present study was to evaluate the melatonin effect on sleep quality in patients with cancer.
Methods: This quasi-experimental study was performed on cancer patients with trouble sleeping who were treated with melatonin (3 mg per day) for a month. Sleep quality according to the Pittsburgh sleep quality index (PSQI) questionnaire was evaluated before and after taking melatonin. This study was conducted in the Oncology Clinic of Imam Reza Hospital, Kermanshah City in Iran from August 2016 to February 2018.
Results: There was a significant difference between the sleep quality of patients with cancer before and after taking melatonin (P<0.05). In other words, before taking melatonin, sleep quality of none of the patients was not optimal but after taking melatonin, the sleep quality of 52% of patients was satisfactory. Also, there was a significant difference between the components of subjective sleep quality (P<0.001), sleep latency (P<0.001), sleep duration (P<0.001), sleep efficiency rate (P<0.001), sleep disturbances (P=0.001), and daytime dysfunction (P<0.001) of patients with cancer before and after taking melatonin. There was no significant difference between the components of subjective sleep quality, sleep latency, sleep duration, sleep efficiency rate, sleep disturbances, and daytime dysfunction of cancer patients with age, sex, kind of cancer, and kind of metastasis before and after taking melatonin (P˃0.05).
Conclusion: According to the mentioned findings, it seems that the administration of melatonin to enhance sleep quality in patients with cancer is effective.