A self-healable and bioadhesive acacia gum polysaccharide-based injectable hydrogel for wound healing acceleration.

The present study aimed at developing an injectable hydrogel based on acacia gum (AG) for wound healing acceleration. The hydrogels were synthetized through metal-ligand coordination mediated by Fe3+ and characterized in terms of gelation time, gel content, initial water content, swelling capacity, water retention ratio, and porosity. Moreover, FTIR, XRD and TGA analyses were performed for the hydrogels and allantoin (Alla) loaded ones. Furthermore, bioadhessiveness, and self-healing as well as antibacterial, toxicity and wound healing potentials of the hydrogels were evaluated. The hydrogels displayed fast gelation time, high swelling, porosity, and bioadhessiveness, as well as antioxidant, self-healing, antibacterial, blood clotting, and injectability properties. FTIR, XRD and TGA analyses confirmed hydrogel synthesis and drug loading. The Alla-loaded hydrogels accelerated wound healing by decreasing the inflammation and increasing the cell proliferation as well as collagen deposition. Hemocompatibility, cell cytotoxicity, and in vivo toxicity experiments were indicative of a high biocompatibility level for the hydrogels. Given the advantages of fast gelation, injectability and beneficial biological properties, the use of Alla-loaded hydrogels could be considered a new remedy for efficient wound healing.

Chronic light deprivation induces different effects on spatial and fear memory and hippocampal BDNF/TRKB expression during light and dark phases of rat diurnal rhythm.

Disruptions in light/dark cycle have been associated with an altered ability to form and retrieve memory in human and animals. Animal studies have shown that chronic light deprivation disrupts the light/dark cycle and alters the neural connections that mediate hippocampal memory formation. In order to better understand how light deprivation affects the formation and retrieval of memory in adult rats, we examined the effect of total darkness on spatial and auditory fear learning and memory formation and BDNF/TRKB protein levels during the light and dark phases of the rat circadian cycle. Male Wistar rats (n = 60), were randomly divided into two main groups: normal rearing (NR, 12 h light/dark cycle for 3 weeks) and dark rearing (DR, kept in constant darkness for 3 weeks); and each of these groups had a "light (day)" and "dark (night)" sub-group. After 3 weeks, the Morris Water maze and auditory fear conditioning were used to assess spatial and fear memory acquisition and retrieval, respectively. BDNF and TRKB protein levels in the hippocampus of rats from the four sub-groups were measured by Western blot, at the completion of the 3 week constant darkness exposure and after the behavioral experiments. These studies revealed that DR for 3 weeks impaired spatial memory retrieval and enhanced extinction of auditory fear memory specifically during the light (day) phase. DR also eliminated the normal fluctuations in BDNF/TRKB levels observed in the hippocampus across the light/dark cycle.

Sex-dependent effects of postweaning exposure to an enriched environment on novel objective recognition memory and anxiety-like behaviors: The role of hippocampal BDNF level.

Exposure to enriched environment (EE) has been indicated to enhance cognitive functions, hippocampal neural plasticity, neurogenesis, long-term potentiation, and levels of the brain-derived neurotrophic factor (BDNF) in laboratory animals. Also, studies on the sex-dependent effects of exposure to EE during adolescence on adult cognitive functions are less. This is important because the beneficial effects of EE may be predominant in the adolescence stage. Therefore, the present study was designed to compare the effects of EE during adolescence (PND21-PND60) on novel objective recognition memory (NORM), anxiety-like behaviors, and hippocampal BDNF mRNA level in the adult male and female rats. Assessment of NORM and anxiety-like behaviors has been done by novel objective recognition task, open field (OF), and elevated plus maze (EPM), respectively. The expression of BDNF mRNA level was also evaluated by quantitative RT-PCR. Our findings demonstrated that housing in the EE during adolescence improves NORM in adult male rats. Also, exposure to EE during adolescence had a different effect on anxiety-like behaviors in both sexes. Additionally, our results indicated an augmented BDNF level in the hippocampus of male and female rats. In conclusion, adolescent exposure to EE has sex-dependent effects on cognitive functions and anxiety-like behaviors and increases BDNF mRNA expression in the hippocampus of both male and female rats; thus, BDNF is an important factor that can mediate the beneficial effects of EE and running exercise on cognitive functions and psychiatric traits.

Sulfur dioxide reduces hippocampal cell death and improves learning and memory deficits in a rat model of transient global ischemia/reperfusion.

OBJECTIVES: According to recent the findings, sulfur dioxide (SO2) is produced by the cardiovascular system, influencing some major biological processes. Based on previous research, SO2 exhibits antioxidant effects and inhibits apoptosis following cardiac ischemia/reperfusion. Therefore, the objective of the current study was to examine the neuroprotective impact of SO2 following global cerebral ischemia/reperfusion (I/R). MATERIALS AND METHODS: Forty-eight male Wistar rats that weighed 260-300 g, were randomly allocated into 4 groups: sham group (n=12), I/R group (n=12), and I/R+SO2 groups (NaHSO3 and Na2SO3; 1:3 ratio; 5 and 10 µg/kg, respectively; for 3 days, n=12). Cerebral ischemia model was prepared by occlusion of both common carotid arteries for 20 min. Saline as a vehicle and SO2 donor at doses 5 µg/kg (intraperitoneally) were injected for 3 days after reperfusion. Four days after ischemia, the passive avoidance memory test was carried out in four groups, and after behavioral assessment, necrosis, apoptosis, and antioxidant enzyme analysis were carried out. RESULTS: O2 treatment could significantly improve memory impairments in rats with cerebral ischemia/reperfusion (I/R) (P<0.05). An increase in both superoxide dismutase and glutathione and a reduction in malondialdehyde were reported in the SO2 group versus the ischemic group (P<0.05). Moreover, SO2 could significantly decrease necrotic and apoptotic cells in the CA1 region (P<0.01). CONCLUSION: According to the findings, SO2 exerts significant neuroprotective effects on cerebral I/R due to its antioxidant activity.

Effects of Spirulina platensis microalgae on antioxidant and anti-inflammatory factors in diabetic rats.

OBJECTIVES: Lipid peroxidation and hyperglycemia are common signs for diabetes. Natural antioxidants such as Spirulina platensis microalgae (SPM) may prevent lipid peroxidation and hyperglycemia. This study aimed to evaluate the effects of SPM on antioxidant and anti-inflammatory in diabetic rats. MATERIALS AND METHODS: Sixty-four rats were divided into eight groups (n=8) and orally treated with 0, 10, 20 and 30 mg/kg body weight of SPM extract. Experimental groups included diabetic rats fed with 0 (DC), 10, 20 and 30 mg/kg SPM. Healthy rats were treated with 0 mg/kg SPM (HC), 10 mg/kg SPM, 20 mg/kg SPM and 30 mg/kg SPM. At the end of the trial, blood samples were collected and the plasma concentrations of trace minerals (TMs), biochemical parameters, and antioxidant enzymes in liver were evaluated. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), TNF-α (tumor necrosis factor-alpha) and IL-6 (interleukin-6) were evaluated. RESULTS: Our findings showed that diabetes significantly lowered the plasma concentration of TMs and antioxidant enzymes in liver and also increased the levels of malondialdehyde, glucose, lipid profile, AST, ALT, TNF-α and IL-6 (DC vs HC). However, an oral supplement of SPM (20 and 30 mg/kg body weight) lowered levels of malondialdehyde level, glucose, lipid parameters, AST, ALT, TNF-α and IL-6. The same levels increased the plasma contents of zinc, iron, copper and selenium and activity of antioxidant enzymes (P<0.05). CONCLUSION: It can be concluded that diabetes decreases TM concentration and antioxidant enzymes and also increases lipid profile, glucose, AST, ALT, TNF-α and IL-6 concentrations. Inclusion of SPM supplementing (20 and 30 mg/kg body weight) increased some TMs and antioxidant enzymes. SPM may provide TMs for synthesis of antioxidant enzymes which subsequently reduce lipid profile, glucose concentration and anti-inflammatory responses.

Infralimbic dopamine D2 receptors mediate glucocorticoid-induced facilitation of auditory fear memory extinction in rats.

The infralimbic (IL) cortex of the medial prefrontal cortex plays an important role in the extinction of fear memory. Also, it has been showed that both brain glucocorticoid and dopamine receptors are involved in many processes such as fear extinction that drive learning and memory; however, the interaction of these receptors in the IL cortex remains unclear. We examined a putative interaction between the effects of glucocorticoid and dopamine receptors stimulation in the IL cortex on fear memory extinction in an auditory fear conditioning paradigm in male rats. Corticosterone (the endogenous glucocorticoid receptor ligand), or RU38486 (the synthetic glucocorticoid receptor antagonist) microinfusion into the IL cortex 10 min before test 1 attenuated auditory fear expression at tests 1-3, suggesting as an enhancement of fear extinction. The effect of corticosterone, but not RU38486 was counteracted by the dopamine D2 receptor antagonist sulpiride pre-treatment administered into the IL (at a dose that failed to alter freezing behavior on its own). In contrast, intra-IL infusion of the dopamine D1 receptor antagonist SCH23390 pre-treatment failed to alter freezing behavior. These findings provide evidence for the involvement of the IL cortex D2 receptors in CORT-induced facilitation of fear memory extinction.