Physiology and Pharmacology
Volume:25 Issue: 1, Mar 2021

The use of animals in experiments and their role in the development of medical sciences are undeniable. Humane endpoints terminate pain and distress in laboratory animals, which are experimented in painful procedures and an involuntary manner. This study was going to review studies published in this area to assist researchers in developing their approach.

Articles used in this review study were obtained from relevant databases including Pubmed, Scopus, Science Direct, OVID, SID, Magiran and Google scholar.

“Humane endpoints” or killing the animal humanely means the point at which an experimental animal’s pain and/or distress is terminated. This pain and distress are not necessarily accompanied by clinical symptoms and it can also be recognized by biochemical, physiological and molecular biomarkers testing.

Regarding the extensive use of laboratory animals, the aim is not only to take care of animals but also to develop knowledge and prevent unintentional animal suffering and death. Increasing awareness of ethical issues regarding research animal use needs scientific information and designing experiments, which are terminated immediately after achieving main goals. Otherwise, it threatens the life of animal and leads to the animal suffering.

The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in 2020, which has a substantial structural similarity to severe acute respiratory syndrome coronavirus (SARS-CoV) that caused the outbreak in 2003, is currently a threat to global health. Lung involvement is the principal clinical feature in infected patients but extra-pulmonary clinical presentations are also common. The reasons for the extensive involvement of other organs are not yet clear. Angiotensin-converting enzyme 2 (ACE2), the key peptide of renin–angiotensin system (RAS), has recently identified as a major receptor for the both SARS-CoV and SARS-CoV-2 that might be a main target of coronavirus infection. ACE2 is mainly expressed in the pulmonary pneumocytes, the small intestine enterocytes as well as the proximal tubule epithelial cells of the kidneys. In addition to the respiratory tract infection symptoms, the noticeable prevalence of gastrointestinal symptoms as well as kidney impairment in hospitalized infected patients highlights other routes of infection/transmission. In present review, we discussed the role of RAS with emphasis on ACE2 in the pathogenesis of SARS-CoV and SARS-CoV-2, particularly in gastrointestinal and kidney manifestations of the diseases.

Chronic stress, which has been prevalent in human life, induce structural changes in the hippocampus. Depression and impairment of memory are serious comorbidities of chronic stress. In this study, we evaluated the impact of an Iranian honey pretreatment on memory deficit, depression and the hippocampal neuronal loss in the chronic unpredictable mild stress (CUMS) model.

Adult male Wistar rats were divided into the control groups that received water or honey (0.2 or 2g/kg) and CUMS groups that subjected different, randomly and unpredictable mild stressors for 4 weeks. Ten days before starting the CUMS procedures, the animals received honey (0.2 or 2g/kg, daily, orally), which was continued until sacrificing. Morris water maze and sucrose performance tests were used to evaluate the spatial learning and memory and depressive-like behavior in the animals respectively. Hippocampus and whole brain samples were collected for further biochemical and histological analysis.

Honey reversed the depression-like behavior and ameliorated the spatial memory deficit induced by CUMS. Also, honey decreased cell death in the hippocampus and reduced the malondialdehyde level in treated animals.

These results revealed that honey diminished learning and memory deficits and depression in chronic stress conditions.

Although several animal studies have indicated the antiepileptic effect for curcumin, there are reports stating the null antiepileptic effect of this substance. This inconsistency might be due to the low bioavailability of curcumin. Therefore, the current study aimed to assess the effect of oral bovine serum albumin (BSA)-based nanocurcumin on seizure caused by pentylenetetrazol (PTZ) in mice. Furthermore, due to the suggested involvement of JNK signaling in seizure pathology, the hippocampal pattern of JNK phosphorylation (activation) was evaluated.

BSA based nanocurcumin was administered at doses of 50 and 100mg/kg oral gavage to male NMRI mice, one hour before PTZ administration. Intravenous PTZ paradigm was used to determine the threshold dose of PTZ to induce clonic seizures, while the intraperitoneal PTZ paradigm was applied to evaluate the latency for appearance of generalized clonus. Upon completion of intraperitoneal PTZ paradigm experiments, the hippocampi were removed and Western blot analysis was performed to determine the phosphorylated and total forms of JNK.

The results indicated that BSA-based nanocurcumin at the doses of 50 and 100mg/kg could significantly increase the threshold and latency of clonic seizure, which was a significant superior effect compared to natural curcumin. PTZ significantly increased the level of hippocampal JNK phosphorylation, but pretreatment of nanocurcumin did not modify this effect.

The present study shows that converting curcumin to BSA-based nanocurcumin can increase its antiepileptic effect. Furthermore, the antiepileptic effect of nanocurcumin was not associated with a modification in PTZ-induced hippocampal JNK hyper activation.

Scrophularia striata is used in traditional medicine to treat various disorders and has neuroprotective effects. There are no studies about the effects of S. striata on cognitive functions in diazinon (DZN)- exposed rats. According to the results of previous studies, vitamin E (Vit. E) can also act as a protective agent against cognitive impairments. Therefore, the present study was designed to compare the effects of Vit. E and S. striata on DZN-induced behavioral impairments in male rats.

Neuroprotective effects of S. striata (30mg/kg, 5 days/week for 8 weeks) and Vit. E (200mg/kg, 5 days/week for 8 weeks, IP) were assessed through changes in memory, anxiety-like behaviors and pain threshold following DZN exposure. Open field, shuttle box and hot plate were used to examine anxiety-like behaviors, passive avoidance learning and memory as well as pain sensitivity, respectively.

Our findings indicated that exposure to DZN caused a significant decrease in memory retention and an increase in anxiety-like behaviors. S. striata and Vit. E administration compensated memory and emotional impairments induced by DZN. As well as, S. striata alone decreased reaction time against thermal stimulus in the hot plate test. The findings of the present study also indicated that exposure to DZN significantly decreased body weight, while S. striata and Vit. E consumption restored it.

Results of our study indicated the protective effects of S. striata consumption like Vit. E against DZN-induced disruptions in anxiety, cognitive function and body weight loss.

The periaqueductal gray (PAG) region plays an essential role in the modulation of nociception. Also, lateral PAG (lPAG) is involved in reward circuitry by the dopaminergic system in addiction. The present study investigated the blockade of D1/D2-like dopamine receptors in the lateral PAG region affects morphine self-administration with and without exercise.

Rats were divided into six groups. The rats were initially trained to receive small pellets of food by pressing an active lever in the self administration apparatus. Exercise groups were run on a treadmill at 20m/min, 5 days/week, for 4 weeks before the surgery. Then rats were bilaterally implanted with cannulae in lPAG. The SCH23390 and sulpiride were microinjected into the lPAG, 5min before receiving morphine. Afterward, the animals were allowed to self administer morphine in 2h sessions over 11 consecutive days. At last, the numbers of lever pressing, infusion times and withdrawal symptoms were measured.

The results showed the number of active lever pressing was significantly increased in the morphine group compared to other groups in self-infusion during 11 days. Exercise significantly reversed the detrimental effects of morphine self-administration after five days. However, the synergistic effect of injected sulpiride into the lPAG region with exercise training was more pronounced on the amelioration of morphine than on the combinatory effect of SCH23390 with exercise.

The findings suggested that the D2 dopamine receptor in the lPAG region was involved in the morphine addiction via the dopaminergic system and exercise training in combination with antagonists could reduce the rewarding properties of morphine.

Many physiological, biochemical and toxicological reactions are occurred in liver. Therefore, healthy function of this organ is vital for the whole body. In spite of having potent endogenous antioxidant system, lots of reactions in liver make it more susceptible to stressors. It is established that improving the potency of liver antioxidants can increase its ability to resist against different kinds of oxidative stressors. Therefore, this study designed to determine whether p-coumaric alleviate ischemia-reperfusion-induced hepatic injury (IRI) in rats.

Thirty-two rats were randomly assigned in sham, p-coumaric acid (PC), ischemia-reperfusion (IR) and p-coumaric acid pretreated IR (PC+IR) groups (n=8 in each group). Animals in sham group underwent laparotomy but not IR injury; rats in PC group did not experience any surgical procedures; IR and PC+IR groups underwent hepatic IR injury. P-coumaric acid at 100mg/kg were given for 7 consecutive days to PC and PC+IR groups. The last dose of p-coumaric acid was injected just before surgery on 7th days of experiment. The levels of malondialdehyde, TAC, ALT and AST were determined. A molecular evaluation to quantify the gene expression of SOD and GPx was done in liver homogenate.

P-coumaric mitigated the hepatic injuries induced by IR and improved TAC, ALT, AST, SOD and GPx. This pretreatment was also decreased MDA level.

The current outcomes showed that PC via improving the endogenous level of antioxidants in liver tissues and inhibiting IR-induced inflammation maintain the liver structure and function of liver against IR.

Extracellular signal-regulated kinase 1 and 2 (ERK1/2) are important members of mitogen-activated protein kinases (MAPK), which are actively involved in the shaping of cellular responses to different stimuli; however, these responses are somehow contradicting. It is believed that time is a crucial factor in the determination of these effects. Therefore, the present work was designed to obtain a more vivid view about the effect of time on ERK activity and its relation to cell viability.

In the first step, we challenged cultured PC12 cells with different doses of lipopolysaccharides (LPS) for different time intervals (3, 6, 24 and 48h) and the cell viability was checked by MTT test. Thereafter, we cultured the cells in 6-well plates and treated them with the effective dose (10μg/ml) for the abovementioned intervals and the level of ERK phosphorylation, as the active form, was assessed in the Western blotting analysis.

The results showed that treating cells with 10μg/ml LPS reduces cell viability after 48h. While being ineffective in shorter periods of time, ERK activity has a fluctuating trend, so that it reaches the highest level at 6h, thereafter it declines to the lowest level at 24h and partially increases again at 48h.

These results imply that time is a determinant factor in the activity of ERK and single-point assessments may result in misinterpretation.

Tamoxifen has been used in the treatment of metastatic malignant melanoma more common with other agents in the combined therapy. Up-regulated activity of the mevalonate pathway has been shown in a range of different cancers. Atorvastatin is the most commonly used statin approved for cholesterol reduction by inhibiting the mevalonate pathway and has been shown to inhibit tumor growth. In the present study, we used atorvastatin and tamoxifen combination therapy on B16f10 mouse melanoma cell lines to study whether atorvastatin could increase the sensitivity of melanoma cells to the chemotherapeutic agent such as tamoxifen.

The cell line was treated with different concentrations of tamoxifen and/or atorvastatin for 24 and 48h and the effects of treatment on p53 and RhoA were investigated using quantitative RT-PCR.

The combination of atorvastatin and tamoxifen resulted in a potentiation antitumor effect via up-regulation of p53 and down-regulation of RhoA expression against melanoma tumors in vitro. Furthermore, we demonstrated the combination of atorvastatin with tamoxifen could reduce tamoxifen dose to minimize possible detrimental side effects in melanoma.

Our results suggested that atorvastatin as a combined therapy with tamoxifen may provide a new approach for improving the efficacy and treating against melanoma cancer but needs further exploration in clinical trials.

Stress and fear caused by computer games have been shown to have various effects on the cognitive system. This work was aimed to investigate the effects of short-time horror computer games on cognitive indicators.

A total of twenty female subjects were recruited and divided into experimental and control groups. All required tests were performed before and after the intervention (playing or watching horror game) on the control and experimental groups. The saliva samples were collected before and after the intervention to measure levels of cortisol and alpha-amylase. Also, blood was taken before and during the game from each subject to evaluate plasma levels of oxytocin and brain-derived neurotrophic factor. The Brain waveforms were acquired by Emotive brain signal recording device before and after the intervention. Data analysis was conducted using R and MATLAB software.

The cortisol and alpha-amylase levels were shown to significantly increase after the horror game playing. Also, the levels of oxytocin were significantly higher after the experimentation. The levels of brain-derived neurotrophic factor were displayed to reduce after the experimentation. The results of the brainwave analysis revealed that the average stress index was significantly higher, while the average attention index was lower after playing the game. No significant difference in the study variables was observed in the control group.

Horror computer games may have adverse effects on the activity of the stress system in the central nervous system. Fear-induced stress was shown to relatively undermine some cognitive elements.