Hypothalamic pathways regulate the anorectic action of p-chloro-diphenyl diselenide in rats

4-Phenylselanyl-7-chloroquinoline attenuates hepatic injury triggered by neonatal exposure to monosodium glutamate in rats

AIMS

Obesity is associated with a spectrum of hepatic abnormalities that can be experimentally induced by injections of monosodium glutamate (MSG) in neonatal rodents. We investigated the protective actions of the repeated therapy with 4-phenylselenyl-7-chloroquinoline (4-PSQ), a quinoline derivative containing selenium, on damage to the liver triggered by early postnatal administration of MSG in male Wistar rats.

MAIN METHODS

Neonatal rats received MSG (4 g/kg, subcutaneous route) or saline (1 ml/kg) from 5 to 14 postnatal day (PND) to induce obesity with consequent damages in the liver. 4-PSQ treatment (5 mg/kg) or canola oil (1 ml/kg) was administered from 60 to 76 PND by the intragastric route. On 76 PND, animals were anesthetized for blood and liver collection. Plasma markers of hepatic function, hepatic lipoperoxidation levels and histology analysis of liver tissue were assessed.

KEY FINDINGS

Our data revealed that treatment with 4-PSQ reverted the increase in plasma transaminases activities observed in MSG rats. Treatment with 4-PSQ reduced plasma lactate levels in obese rats. In the liver, MSG elevated the content of lipoperoxidation which was reverted by 4-PSQ administrations. Lastly, 4-PSQ therapy attenuated the histological alterations induced by MSG.

SIGNIFICANCE

Together, the results indicate a hepatoprotective action of repeated treatment with 4-PSQ in obese rats.

The neurotherapeutic role of a selenium-functionalized quinoline in hypothalamic obese rats

RATIONALE

Obesity is considered one of the major global health problems and increases the risk of several medical complications, such as diabetes and mental illnesses.

OBJECTIVE

The present study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) on obesity parameters, behavioral and neurochemical alterations in hypothalamic obese rats.

METHODS

Male Wistar rats received subcutaneous neonatal injections of monosodium glutamate (MSG, 4g/kg) or saline. After the Lee Index evaluation, rats were divided into groups and treated with 4-PSQ (5 mg/kg, intragastric route) or canola oil once a day (post-natal days (PND) 60→76). Open-field, elevated plus-maze, forced swim task, object recognition/location memory, and stepdown inhibitory avoidance tasks were conducted from PND 66 to 74. On PND 76, rats were euthanized and epididymal fat, blood, cerebral cortex, andhippocampus were removed. Blood biochemical parameters and cortical/hippocampal acetylcholinesterase (AChE) and Na /K -ATPase activities were assessed.

RESULTS

MSG increased the Lee Index characterizing the chemically induced hypothalamic obesity model. 4-PSQ reversed the increases of epididymal fat, blood glucose, and triglyceride levels caused by MSG exposure. 4-PSQ attenuated anxiety-like and depression-like behaviors induced by neonatal administrations of MSG. Memory deficits found in MSG-obese rats were reversed by treatment with 4-PSQ. Neurochemical alterations produced by MSG evidenced by stimulation ofNa⁺/K⁺-ATPase and AChE activities in the cerebral cortex and hippocampus of rats were normalized by 4-PSQ treatment.

CONCLUSIONS

In brief, 4-PSQ therapy improved hypothalamic obesity-related parameters, as well as psychiatric symptoms, cognitive impairment, and neurochemical alterations found in obese rats.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Selenium and Selenoproteins in Adipose Tissue Physiology and Obesity

Selenium (Se) homeostasis is tightly related to carbohydrate and lipid metabolism, but its possible roles in obesity development and in adipocyte metabolism are unclear. The objective of the present study is to review the current data on Se status in obesity and to discuss the interference between Se and selenoprotein metabolism in adipocyte physiology and obesity pathogenesis. The overview and meta-analysis of the studies on blood Se and selenoprotein P (SELENOP) levels, as well as glutathione peroxidase (GPX) activity in obese subjects, have yielded heterogenous and even conflicting results. Laboratory studies demonstrate that Se may modulate preadipocyte proliferation and adipogenic differentiation, and also interfere with insulin signaling, and regulate lipolysis. Knockout models have demonstrated that the selenoprotein machinery, including endoplasmic reticulum-resident selenoproteins together with GPXs and thioredoxin reductases (TXNRDs), are tightly related to adipocyte development and functioning. In conclusion, Se and selenoproteins appear to play an essential role in adipose tissue physiology, although human data are inconsistent. Taken together, these findings do not support the utility of Se supplementation to prevent or alleviate obesity in humans. Further human and laboratory studies are required to elucidate associations between Se metabolism and obesity.

Keap1/Nrf2/HO-1 signaling pathway contributes to p-chlorodiphenyl diselenide antidepressant-like action in diabetic mice

RATIONALE

The association between depression and diabetes has been recognized for many years, but the nature of this relationship remains uncertain.

OBJECTIVES

This study investigated the antidepressant-like effect of (p-ClPhSe)₂ on mice made diabetic by streptozotocin (STZ) and the contribution of cerebral cortical Keap1/Nrf2/HO-1 signaling pathway for this effect.

METHODS

Male adult Swiss mice received streptozotocin (STZ, 200 mg/kg, i.p.) to induce diabetes (glycemia ≥ 200 mg/dl) or citrate buffer (5 ml/kg, control group). The mice were treated with (p-ClPhSe)₂ at the dose of 5 mg/kg, i.g., for 7 days. Mice performed behavior tests, tail suspension (TST), and forced swimming tests (FST), to evaluate depressive-like phenotype.

RESULTS

Diabetic mice showed an increase in immobility time in the TST and FST when compared to the control group. The protein contents of Keap1/Nrf2/HO-1 pathway were decreased in the cerebral cortex of diabetic mice. Diabetic mice had an increase in the relative adrenal weight and a decrease in the protein content of glucocorticoid receptor. The levels of TBARS and RS and SOD activity were found altered in the cerebral cortex of diabetic mice. The number of FJC-positive cells was increased in the cerebral cortex of diabetic mice. Treatment with (p-ClPhSe)₂ was effective against depressive-like phenotype, oxidative stress, and FJC-positive cells of diabetic mice. (p-ClPhSe)₂ did not reverse the parameters of HPA axis evaluated in this study. (p-ClPhSe)₂ modulated the cerebral cortical Keap1/Nrf2/HO-1 pathway in diabetic mice.

CONCLUSIONS

This study demonstrates the contribution of cerebral cortical Keap1/Nrf2/HO-1 pathway in the (p-ClPhSe)₂ antidepressant-like action in diabetic mice.

4,4'-Dichlorodiphenyl diselenide reverses a depressive-like phenotype, modulates prefrontal cortical oxidative stress and dysregulated glutamatergic neurotransmission induced by subchronic dexamethasone exposure to mice

Dexamethasone (DEX) is a synthetic agonist of glucocorticoid receptors that has been associated with neurotoxicity and neuropsychiatric diseases. (p-ClPhSe)₂ is an organoselenium compound reported to have antioxidant, antidepressant-like, and neuroprotective actions. This study investigated whether antioxidant activity and modulation of the glutamatergic system contribute to the antidepressant-like effect of (p-ClPhSe)₂ in mice subchronically exposed to DEX. Swiss mice received intraperitoneal injections of DEX (2 mg/kg) or saline (vehicle) once a day for 21 days. After, the mice received (p-ClPhSe)₂ (1-10 mg/kg) or mineral oil (vehicle) by the intragastric route (i.g.) for 7 days. The mice exposed to DEX were treated with fluoxetine (20 mg/kg, i.g.) once a day for 7 days. 24 h after the last treatment, the animals performed the locomotor activity (LMA), tail suspension, and forced swimming tests. Ex vivo assays were performed in samples of prefrontal cortex (PFC). The results show that (p-ClPhSe)₂ reversed depressive-like behavioral phenotype induced by DEX without affecting LMA. Further, (p-ClPhSe)₂ at all doses reduced ROS levels and increased CAT activity in the PFC of DEX-exposed mice. The highest dose of (p-ClPhSe)₂ was effective against the decrease of SOD activity in the PFC of mice exposed to DEX. (p-ClPhSe)₂ increased the [³H] glutamate uptake/release and decreased the Na⁺/K⁺-ATPase activity as well as the EAAT1 and NMDA R2A protein contents in the PFC of DEX-exposed mice. Regarding the NMDA R2B levels, there was no difference among experimental groups. In conclusion, this study reveals the effectiveness of (p-ClPhSe)₂ in reversing the depressive-like phenotype of DEX-exposed mice. In addition, (p-ClPhSe)₂ modulated oxidative stress and glutamate neurotransmission in the PFC of mice subchronically exposed to DEX.

(p-ClPhSe)2 modulates hippocampal BDNF/TrkB signaling and reverses memory impairment induced by diabetes in mice

Diabetes is a metabolic disease characterized by hyperglycemia because of insulin resistance and/or insufficient insulin release. The most common diabetic brain complications include cognitive decline and depression. The present study investigated whether the 4-4'-dichlorodiphenyl diselenide (p-ClPhSe)₂ is effective against memory impairment induced by diabetes in mice and the role of hippocampal BDNF/TrkB signaling in this effect. Male adult Swiss mice received an injection of streptozotocin (STZ) (200 mg/kg, i.p.) to induce diabetes. The results revealed that STZ injection in mice resulted in resilience (glycemia <200 mg/dl) or diabetes (glycemia ≥200 mg/dl). The vehicle-control group received citrate buffer (5 ml/kg). The animals were subchronically treated with (p-ClPhSe)₂ (1 or 5 mg/kg, i.g.) for 7 days. Mice performed a battery of well-validated behavior tests designated to evaluate memory, object recognition (ORT), object location (OLT), and Morris water maze (MWM). The hippocampal protein contents of the BDNF/TrkB pathway were determined in the samples of experimental groups. Fluoro Jade C (FJC) was used for staining degenerating neurons. The STZ administration resulted in memory impairment that was demonstrated in the mouse ORT, OLT, and MWM tests. The molecular findings indicate an increase in hippocampal protein levels of proBDNF and TrKB but a decrease in those of mBDNF and pCREB in diabetic mice. The number of FJC-positive cells was increased in the hippocampus of diabetic mice. (p-ClPhSe)₂ at the dose of 5 mg/kg modulated the hippocampal BDNF/TrkB pathway, reduced FJC-positive cells and reversed memory impairment induced by STZ in mice. These findings demonstrate the effectiveness of (p-ClPhSe)₂ against memory impairment caused by diabetes in mice. (p-ClPhSe)₂ modulated the hippocampal BDNF/TrkB signaling pathway in diabetic mice.