The protective and therapeutic effects of vinpocetine, a PDE1 inhibitor, on oxidative stress and learning and memory impairment induced by an intracerebroventricular (ICV) injection of amyloid beta (aβ) peptide

Alzheimer's disease (AD) is a neurodegenerative disease leading to cognitive and memory impairment. This study aimed at investigating the therapeutic and preserving effects of vinpocetine on amyloid beta (Aβ)-induced rat model of AD. Sixty male adult Wistar rats were randomly divided into 6 groups (n = 10 per group) as follows: 1; control, 2; sham, 3; Aβ, 4; pre-treatment (vinpocetine + Aβ): oral gavage administration of vinpocetine at 4 mg/kg for 30 days followed by intracerebroventricular (ICV) injection of Aβ, 5; treatment (Aβ + vinpocetine): Aβ ICV injection followed by vinpocetine administration for 30 days, 6; pre-treatment + treatment (vinpocetine + Aβ + vinpocetine): vinpocetine administration for 30 days before and 30 days after AD induction. Following treatments, the animals' learning and memory were investigated using passive avoidance learning (PAL) task, Morris water maze (MWM), and novel object recognition (NOR) tests. The results demonstrated that Aβ significantly enhanced escape latency and the distance traveled in the MWM, decreased step-through latency, and increased time spent in the dark compartment in PAL. Vinpocetine ameliorated the Aβ-infused memory deficits in both MWM and PAL tests. Administration of vinpocetine in the Aβ rats increased the discrimination index of the NOR test. It also significantly diminished the nitric oxide and malondialdehyde levels and restored the reduced glutathione (GSH) levels. Vinpocetine can improve memory and learning impairment following Aβ infusion due to its different properties, including antioxidant effects, which indicates that vinpocetine administration can lead to the amelioration of cognitive dysfunction in AD.

Antidiabetic potential of salvianolic acid B in multiple low-dose streptozotocin-induced diabetes

CONTEXT

Salvianolic acids are the most abundant water-soluble compounds extracted from the herb Salvia miltiorrhiza L. (Lamiaceae) with antioxidant and protective effects.

OBJECTIVE

This study evaluates the antidiabetic effect of salvianolic acid B (Sal B) in multiple low-dose streptozotocin (MLDS)-induced diabetes in rat.

MATERIALS AND METHODS

Rats were divided into control, Sal B40-treated control, diabetic, Sal B20-, and Sal B40-treated diabetic groups. Sal B was daily administered at doses of 20 or 40 mg/kg (i.p.), started on third day post-STZ injection for 3 weeks. Serum glucose and insulin level and some oxidative stress markers in pancreas were measured in addition to the oral glucose tolerance test (OGTT), histological assessment, and apoptosis determination.

RESULTS

After 3 weeks, treatment of diabetic rats with Sal B20 and Sal B40 caused a significant decrease of the serum glucose (p < 0.05-0.01) and improvement of OGTT. Meanwhile, serum insulin was significantly higher in Sal B20- and Sal B40-treated diabetics (p < 0.01) and treatment of diabetics with Sal B40 significantly lowered malondialdehyde (MDA) (p < 0.05), raised glutathione (GSH) (p < 0.05), and activity of catalase (p < 0.01) with no significant change of nitrite. Furthermore, the number of pancreatic islets (p < 0.05) and their area (p < 0.01) was significantly higher and apoptosis reactivity was significantly lower (p < 0.05) in the Sal B40-treated diabetic group versus diabetics.

DISCUSSION AND CONCLUSION

Three-week treatment of diabetic rats with Sal B exhibited antidiabetic activity which is partly exerted via attenuation of oxidative stress and apoptosis and augmentation of antioxidant system.

Influence of hippocampal GABAB receptor inhibition on memory in rats with acute β-amyloid toxicity

The neurotransmitter γ-aminobutyric acid (GABA) is involved in the process of memory. It has been reported that the inhibition of GABA_B receptors has beneficial effects on cognition. The aim of this study was to investigate the role of CGP35348 (a GABA_B receptor antagonist) on dentate gyrus GABA_B receptor inhibition and its effects on learning and memory impairments that had been induced in adult male rats by microinjection of β-amyloid (Aβ). Seventy Wistar male rats were randomly divided into seven groups: control, sham (receiving the Aβ vehicle only), Aβ, Aβ + CGP35348 (1, 10, and 100 μg/μL), and CGP35348 alone (10 μg/μL). Memory impairment was induced by unilateral interventricular microinjection of Aβ (6 μg/6 μL). Rats were cannulated bilaterally in the dentate gyrus, and then, they were treated for 20 consecutive days. Learning and memory were assessed using the novel object recognition and passive avoidance learning tests. The discrimination index and the step-through latency were significantly increased in the Aβ + CGP35348 group in comparison to the Aβ only group (P < 0.05 and P < 0.01, respectively). Data showed that the discrimination index was decreased in the Aβ + CGP35348 group in comparison with the control group (P < 0.05) and sham group (P < 0.01). Moreover, the step-through latency was significantly decreased in the Aβ + CGP35348 group in comparison to the control and sham groups (P < 0.01). Data from this study indicated that intra-hippocampal microinjection of the GABA_B receptor antagonist counteracts the learning, memory, and cognitive impairments induced by Aβ. It can be concluded that the GABA_B receptor antagonist is a possible therapeutic agent against the progression of acute Aβ toxicity-induced memory impairment.

Cancer patients' understanding of longitudinal EORTC QLQ-C30 scores presented as bar charts

OBJECTIVE

To investigate cancer patients' understanding of graphical presentations of longitudinal EORTC QLQ-C30 scores.

METHODS

We conducted semi-structured interviews with brain tumour patients participating in routine patient-reported outcome (PRO) monitoring. We assessed understanding of longitudinal quality of life (QOL) profiles, presented as bar charts objectively and with self-ratings. In addition, patients' opinions on congruency of the QOL scores with their self-perceived health status were evaluated.

RESULTS

We recruited 40 brain tumour patients (57.5% female; mean age 52.7, SD 13.7). In total, 90% of patients rated the graphs as easy to understand. Accordingly, almost all questions on assessing understanding objectively were answered correctly by at least 80% of the patients. More than 95% indicated that the displayed QOL scores matched their personal perception of symptom burden and functional health in the observed period.

CONCLUSION

Patients are able to understand their QOL results when presented graphically and are able to interpret important changes. Displayed QOL scores obtained with the EORTC QLQ-C30 are consistent with the patients' personal perception of physical and emotional functioning, pain and fatigue.

PRACTICE IMPLICATIONS

Knowledge about patients' understanding of graphically displayed QOL results contributes to creation of optimal evidence-based feedback on the patients' present QOL and its trajectory.

Effects of Buprenorphine on the Memory and Learning Deficit Induced by Methamphetamine Administration in Male Rats

Little is known about the effects of methamphetamine (Meth) and buprenorphine (Bup) on memory and learning in rats. The aim of this investigation was to examine the impact of Meth and Bup on memory and learning. Fourteen male Wistar rats weighing 250–300 g were assigned to four groups: Sham, Meth, Bup, and Meth + Bup and were treated for 1 week. Spatial learning and memory, avoidance learning, and locomotion were assessed using the Morris water maze, passive avoidance learning, and open field tests, respectively. Meth and Bup impaired spatial learning and memory in rats. Co-administration of Meth + Bup did not increase the time spent in the target quadrant compared to Meth alone in the MWM. The Bup and Meh + Bup groups were found with an increase in step-through latency (STLr) and a decrease in the time spent in the dark compartment (TDC). Meth and Bup had no effects on locomotor activity in the open field test. Bup showed a beneficial effect on aversive memory. Since Bup demonstrates fewer side effects than other opioid drugs, it may be preferable for the treatment of avoidance memory deficits in patients with Meth addiction.

Mitochondrial biogenesis and apoptosis as underlying mechanisms involved in the cardioprotective effects of Gallic acid against D-galactose-induced aging

BACKGROUND

Aging is a main risk factor for the development of cardiovascular diseases (CVDs). Gallic acid (GA) is a phenolic compound derived from a wide range of fruits. GA has a wide spectrum of pharmacological properties, including anti-oxidative, anti-inflammatory, and cardioprotective effects. This research was conducted to determine the cardioprotective effect of GA on cardiac hypertrophy in aged rats.

METHODS AND RESULTS

Following histological evaluation and through observing the heart, we found that GA improved the cardiac hypertrophy induced by D-galactose (D-GAL) in cardiac cells. To clarify the causes for this anti-aging effect, we evaluated the malonic dialdehyde levels and antioxidant enzyme activity in rat cardiac tissue. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK-MB) in serum were measured. The levels of genes related to mitochondrial biogenesis, mitophagy, and apoptosis in cardiac tissue were surveyed. The findings represented that GA ameliorated antioxidant enzyme activity while significantly decreasing the malonic dialdehyde levels. Real-time PCR analysis proposed that GA effectively improved mitochondrial biogenesis in the heart via regulating the expression levels of Sirtuin 1 (SIRT1), PPARγ coactivator 1α (PGC1-α), nuclear factor erythroid 2-related factor 2 (Nrf2), and mitochondrial transcription factor A (TFAM). GA also mitigated apoptosis in the heart by modulating the expression levels of B-cell lymphoma protein 2 (Bcl-2) and Bcl-2-associated X (Bax). In addition, GA improved serum LDH and CK-MB levels.

CONCLUSIONS

GA may alleviate aging-induced cardiac hypertrophy via anti-oxidative, mitoprotective, and anti-apoptotic mechanisms.

Royal jelly improves learning and memory deficits in an amyloid β-induced model of Alzheimer's disease in male rats: Involvement of oxidative stress

Alzheimer's disease (AD) as the commonest type of dementia is associated with the cognitive function failure. Oxidative stress performs an essential role in the progression of AD. Royal jelly (RJ) is a natural product of bees with antioxidant and anti-inflammatory properties. The present research aimed to investigate the possible protective effect of RJ on learning and memory in a rat model of Aβ-induced AD. Forty male adult Wistar rats were equally distributed into five groups: control, sham-operated, Aβ (receiving intracerebroventricular (ICV) injection of amyloid beta (Aβ1-40)), Aβ + RJ 50 mg/kg, and Aβ + RJ 100 mg/kg. RJ was administered daily post-surgery by oral gavage for four weeks. Behavioral learning and memory were examined using the novel object recognition (NOR) and passive avoidance learning (PAL) tests. Also, oxidative stress markers, such as malondialdehyde (MDA), total oxidant status (TOS) and total antioxidant capacity (TAC), were assessed in the hippocampus. Aβ reduced step-through latency (STLr) and increased time spent in the dark compartment (TDC) in the PAL task and also decreased discrimination index in the NOR test. Administration of RJ ameliorated the Aβ-related memory impairment in both NOR and PAL tasks. Aβ decreased TAC and increased MDA and TOS levels in the hippocampus, whereas RJ administration reversed these Aβ-induced alterations. Our results indicated that RJ has the potential to ameliorate learning and memory impairment in the Aβ model of AD via attenuating oxidative stress.

Protective effects of geraniol in a male rat model of Alzheimer's disease: A behavioral, biochemical, and histological study

BACKGROUND

Alzheimer's disease (AD) as a neurodegenerative disease can cause behavioral impairments due to oxidative stress. Aging and oxidative conditions are some AD risk factors.

OBJECTIVE

We assessed the influence of geraniol (GR), an acyclic monoterpene alcohol, on behavioral functions, hippocampal oxidative status, and histological alterations in AD rats induced by amyloid-β (Aβ).

METHODS

Male Wistar rats (n = 70) were randomly allocated to the control, sham, AD, control-GR (100 mg/kg; per oral: P.O.), AD-GR (100 mg/kg; P.O.; treatment), GR-AD (100 mg/kg; P.O.; pretreatment), and GR-AD-GR (100 mg/kg; P.O.; pretreatment + treatment) groups. GR administration was done for four continuous weeks. After treatments, novel object recognition (NOR) and Morris water maze (MWM) tests assessed the animals' behavior. Then, hippocampal specimens were collected for biochemical assessment. Finally, the number of intact neurons was identified in the hippocampus using hematoxylin and eosin staining.

RESULTS

Aβ microinjection increased learning and memory deficits in both NOR and MWM tests, oxidative stress status, and neuronal loss. Oral GR administration improved behavioral deficits and reduced oxidative stress status and neuronal loss in the Aβ-infused animals.

CONCLUSIONS

GR ameliorates behavioral impairments through a decrease in neuronal degeneration and oxidative stress.

Effect of ramosetron, a 5-HT3 receptor antagonist on the severity of seizures and memory impairment in electrical amygdala kindled rats

The entorhinal cortex (EC) plays a pivotal role in epileptogenesis and seizures. EC expresses high density of serotonergic receptors, especially 5-HT3 receptors. Cognitive impairment is common among people with epilepsy. The present study investigated the role of 5-HT3 receptor on the severity of seizures and learning and memory impairment by electrical kindling of amygdala in rats. The amygdala kindling was conducted in a chronic kindling manner in male Wistar rats. In fully kindled animals, ramosetron (as a potent and selective 5-HT3 receptor antagonist) was microinjected unilaterally (ad doses of 1, 10 or 100 µg/0.5 µl) into the EC 5 min before the novel object recognition (NOR) and Y-maze tests or kindling stimulations. Applying ramosetron at the concentration of 100 μg/0.5 µl (but not at 1 and 10 µg/0.5 µl) reduced afterdischarge (AD) duration and increased stage 4 latency in the kindled rats. Moreover, the obtained data from the NOR test showed that treatment by ramosetron (10 and 100 µg/0.5 µl) increased the discrimination index in the fully kindled animals. Microinjection of ramosetron (10 and 100 µg/0.5 µl) in fully kindled animals reversed the kindling induced changes in the percentage of spontaneous alternation in Y-maze task. The findings demonstrated an anticonvulsant role for a selective 5-HT3 receptor antagonist microinjected into the EC, therefore, suggesting an excitatory role for the EC 5-HT3 receptors in the amygdala kindling model of epilepsy. This anticonvulsive effect was accompanied with a restoring effect on cognitive behavior in NOR and Y-maze tests.

Neuroprotective effects of vinpocetine, as a phosphodiesterase 1 inhibitor, on long-term potentiation in a rat model of Alzheimer's disease

BACKGROUND

Vinpocetine (Vin) is known as a phosphodiesterase 1 inhibitor (PDE1-I) drug with multilateral effects, including antioxidant and anti-inflammatory activity. In this research, we investigated the neuroprotective and therapeutic effects of Vin through hippocampal synaptic plasticity on a rat's model of Alzheimer's disease (AD) induced by an intracerebroventricular (ICV) injection of beta-amyloid (Aβ).

METHODS

Sixty adult male Wistar rats were randomly divided into six groups: 1. control, 2. sham, 3. Aβ, 4. pretreatment (Vin + Aβ): Vin (4 mg/kg, gavage) for 30 days and then, inducing an AD model by an ICV injection of Aβ(1-42), 5. treatment (Aβ + Vin): inducing an AD model and then receiving Vin for 30 days by gavage, and 7. pretreatment + treatment (Vin + Aβ + Vin): receiving Vin by gavage for 30 days before and 30 days after the induction of an AD model. After these procedures, via stereotaxic surgery, the stimulating electrodes were placed at the perforant pathway (PP) and the recording electrodes were implanted in the dentate gyrus.

RESULTS

Excitatory postsynaptic potential (EPSP) slope and population spike (PS) amplitude in the Aβ group meaningfully diminished compared to the control group after the induction of long-term potentiation (LTP).

CONCLUSIONS

Vin could significantly prevent the Aβ effects on LTP. It can be concluded that pretreatment and treatment with Vin can be neuroprotective against harmful consequences of Aβ on hippocampal synaptic plasticity.

Geraniol improves passive avoidance memory and hippocampal synaptic plasticity deficits in a rat model of Alzheimer's disease

Alzheimer's disease (AD) is the most progressive and irreversible neurodegenerative disease that leads to synaptic loss and cognitive decline. The present study was designed to evaluate the effects of geraniol (GR), a valuable acyclic monoterpene alcohol, with protective and therapeutic effects, on passive avoidance memory, hippocampal synaptic plasticity, and amyloid-beta (Aβ) plaques formation in an AD rat model induced by intracerebroventricular (ICV) microinjection of Aβ_1-40. Seventy male Wistar rats were randomly into sham, control, control-GR (100 mg/kg; P.O. (orally), AD, GR-AD (100 mg/kg; P.O.; pretreatment), AD-GR (100 mg/kg; P.O.; treatment), and GR-AD-GR (100 mg/kg; P.O.; pretreatment & treatment). Administration of GR was continued for four consecutive weeks. Training for the passive avoidance test was carried out on the 36^th day and a memory retention test was performed 24 h later. On day 38, hippocampal synaptic plasticity (long-term potentiation; LTP) was recorded in perforant path-dentate gyrus (PP-DG) synapses to assess field excitatory postsynaptic potentials (fEPSPs) slope and population spike (PS) amplitude. Subsequently, Aβ plaques were identified in the hippocampus by Congo red staining. The results showed that Aβ microinjection increased passive avoidance memory impairment, suppressed of hippocampal LTP induction, and enhanced of Aβ plaque formation in the hippocampus. Interestingly, oral administration of GR improved passive avoidance memory deficit, ameliorated hippocampal LTP impairment, and reduced Aβ plaque accumulation in the Aβ-infused rats. The results suggest that GR mitigates Aβ-induced passive avoidance memory impairment, possibly through alleviation of hippocampal synaptic dysfunction and inhibition of Aβ plaque formation.

Cardioprotective effect of Vitamin D on cardiac hypertrophy through improvement of mitophagy and apoptosis in an experimental rat model of levothyroxine -induced hyperthyroidism

BACKGROUND

Mitochondria are known to be involved in mediating the calorigenic effects of thyroid hormones. With an abundance of these hormones, alterations in energy metabolism and cellular respiration take place, leading to the development of cardiac hypertrophy. Vitamin D has recently gained attention due to its involvement in the regulation of mitochondrial function, demonstrating promising potential in preserving the integrity and functionality of the mitochondrial network. The present study aimed to investigate the therapeutic potential of Vitamin D on cardiac hypertrophy induced by hyperthyroidism, with a focus on the contributions of mitophagy and apoptosis as possible underlying molecular mechanisms.

METHODS AND RESULTS

The rats were divided into three groups: control; hyperthyroid; hyperthyroid + Vitamin D. Hyperthyroidism was induced by Levothyroxine administration for four weeks. Serum thyroid hormones levels, myocardial damage markers, cardiac hypertrophy indices, and histological examination were assessed. The assessment of Malondialdehyde (MDA) levels and the expression of the related genes were conducted using heart tissue samples. Vitamin D pretreatment exhibited a significant improvement in the hyperthyroidism-induced decline in markers indicative of myocardial damage, oxidative stress, and indices of cardiac hypertrophy. Vitamin D pretreatment also improved the downregulation observed in myocardial expression levels of genes involved in the regulation of mitophagy and apoptosis, including PTEN putative kinase 1 (PINK1), Mitofusin-2 (MFN2), Dynamin-related Protein 1 (DRP1), and B cell lymphoma-2 (Bcl-2), induced by hyperthyroidism.

CONCLUSIONS

These results suggest that supplementation with Vitamin D could be advantageous in preventing the progression of cardiac hypertrophy and myocardial damage.

Effect of diminazene on cardiac hypertrophy through mitophagy in rat models with hyperthyroidism induced by levothyroxine

Hyperthyroidism is associated with the alteration in molecular pathways involved in the regulation of mitochondrial mass and apoptosis, which contribute to the development of cardiac hypertrophy. Diminazene (DIZE) is an animal anti-infection drug that has shown promising effects on improving cardiovascular disease. The aim of the present study was to investigate the therapeutic effect of DIZE on cardiac hypertrophy and the signaling pathways involved in this process in the hyperthyroid rat model. Twenty male Wistar rats were equally divided into four groups: control, hyperthyroid, DIZE, and hyperthyroid + DIZE. After 28 days of treatment, serum thyroxine (T4) and thyroid stimulating hormone (TSH) level, cardiac hypertrophy indices, cardiac damage markers, cardiac malondialdehyde (MDA), and superoxide dismutase (SOD) level, the mRNA expression level of mitochondrial and apoptotic genes were evaluated. Hyperthyroidism significantly decreased the cardiac expression level of SIRT1/PGC1α and its downstream involved in the regulation of mitochondrial biogenesis, mitophagy, and antioxidant enzyme activities including TFAM, PINK1/MFN2, Drp1, and Nrf2, respectively, as well as stimulated mitochondrial-dependent apoptosis by reducing Bcl-2 expression and increasing Bax expression. Treatment with DIZE significantly reversed the downregulation of SIRT1, PGC1α, PINK1, MFN2, Drp1, and Nrf2 but did not significantly change the TFAM expression. Moreover, DIZE suppressed apoptosis by normalizing the cardiac expression levels of Bax and Bcl-2. DIZE is effective in attenuating hyperthyroidism-induced cardiac hypertrophy by modulating the mitophagy-related pathway, suppressing apoptosis and oxidative stress.

The Anti-nociceptive Effect of Ellagic Acid in Streptozotocin-induced Hyperglycemic Rats by Oxidative Stress Involvement

Introduction:

Hyperalgesia is among the current complications of diabetes mellitus; oxidative stress and inflammation were influential in its development. As an herbal component, Ellagic Acid (EA) has some biological activities, including antioxidant and anti-inflammatory effects. This study was designed to evaluate the possible beneficial effect of EA on hypernociception in Streptozotocin (STZ)-induced hyperglycemic rats.

Methods:

Forty-eight male Wistar rats were divided into the control (receiving vehicle), hyperglycemic, EA (25 mg/kg)-treated control, EA (50 mg/kg)-treated control, EA (25 mg/kg)-treated hyperglycemic, and EA (50 mg/kg)-treated hyperglycemic groups. Hyperglycemia was induced by a single Intraperitoneal (IP) injection of STZ (60 mg/Kg). EA was administered daily by oral gavage for four weeks. The nociceptive response was assessed using Tail-Flick (TF) and Hot-Plate (HP) tests. Also, oxidative stress markers, including Malondialdehyde (MDA), Total Oxidant Status (TOS), and Total Antioxidant Capacity (TAC) in the serum, were evaluated.

Results:

Hyperglycemic animals were found with significant changes, including a reduction in TF and HP latencies, an elevation in serum MDA level and TOS, and a decrease in serum TAC compared with controls. The treatment of hyperglycemic rats with EA facilitated the reduction of TF latency at the dose of 25 mg/kg and HP latency at 50 mg/kg. Furthermore, EA significantly increased TAC and decreased MDA level at a 50 mg/kg dose and reduced TOS at both doses in the serum of hyperglycemic animals. No significant alterations were found in the parameters studied in EA-treated normal rats.

Conclusion:

These results displayed the antinociceptive effect of EA in hyperglycemic rats via attenuating oxidative stress. Therefore, EA appears to be a promising agent for managing. Hyperglycemic hypernociception.

Highlights

Plain Language Summary

DN is among the most common chronic complications of diabetes among diabetic patients. DPN is mainly characterized by pain perception alterations, increased sensitivity to mild painful stimuli (hyperalgesia), and abnormal pain sensitivity to stimuli. On the other hand, hyperglycemia by induction of multiple changes, such as fatty acid metabolism abnormalities plays a crucial role in developing DN. Oxidative stress and inflammation are involved in the pathogenesis of DPN. The lack of efficacy and various adverse effects of the current medications for DNP, therefore, new therapeutic candidates are continuously required to improve DNP. Several studies reported the antinociceptive activity of EA in different animal models of pain, such as formalin. Since oxidative stress is involved in diabetic hyperalgesia, compounds with antioxidant properties are good candidates for DN management. Therefore, this research aimed to determine the possible effectiveness of EA and evaluate some oxidative stress-related mechanisms.