Apelin 13 Improves Anxiety and Cognition Via Hippocampal Increases BDNF Expression and Reduction Cell Death in Neonatal Alcohol Exposed Rats

Erythropoietin improves spatial and nonspatial memory defects by suppressing oxidative damage, inflammation and apoptosis against ethanol neurotoxicity in the developing male rat hippocampus

Excessive prenatal exposure to ethanol leads to a condition called fetal alcohol spectrum disorder (FASD). The neurotoxicity of alcohol causes changes in the hippocampus of animals during this time, resulting in impaired hippocampus-related functions, including memory/learning and cognition.The liver and kidneys produce erythropoietin (EPO). The synthesis of EPO by immature neurons also plays a decisive role in the embryonic stage. Also, exogenous EPO exerts its neurocognitive effects in the developing brain under pathophysiological conditions. The aim of this study was to investigate the protective effects of EPO administration after ethanol-induced increased neurodevelopmental toxicity. Male Wistar rat pups were intubated with a dose of 5/27 g/kg/day ethanol from postnatal day 2-10, similar to the last trimester of gestation in humans. Immediately thereafter, EPO (1000 /2000 U/kg, s.c.) were injected. Spatial memory was tested with the Morris water maze (days 36-40) and non-spatial recognition memory with the novel object task (days 39-40). Concentrations of antioxidant enzymes and TNF-α (ELISA) and caspase-3 (immunohistochemical staining) was then performed. The current study shows that EPO administration significantly attenuates spatial and nonspatial memory impairment (P < 0.001). EPO dramatically decreased the amount of caspase 3 positive cells in the CA1 area of the hippocampus (P < 0.01). EPO increased total superoxide dismutase activity (P < 0.05), glutathione concentrations (P < 0.05) and catalase levels (P < 0.001). EPO also attenuated the production of TNF-α and malondialdehyde (P < 0.05). Given EPO's protective effect against ethanol-induced increased neurotoxicity, it is a viable treatment option for FASD, although more research is needed.

Protective effect of Apelin-13 on D-glutamic acid-induced excitotoxicity in SH-SY5Y cell line: An in-vitro study

Excitotoxicity, resulting from excessive accumulation of glutamate in the extracellular space, leads to neuronal cell death. This study investigates the protective effects of Apelin-13 on D-Glutamic acid-induced excitotoxicity in SH-SY5Y human neuroblastoma cells, an in-vitro model for neurodegenerative diseases. Unlike the commonly studied L-glutamic acid, this research focuses on D-Glutamic acid to understand its specific impacts. SH-SY5Y cells were treated with varying concentrations of D-Glutamic acid and Apelin-13, followed by analyses at 12 and 24 h to evaluate cell viability, oxidative stress markers, and inflammatory cytokine levels. Cell viability assays revealed significant cytotoxic effects of D-Glutamic acid at doses of 10 mM and 20 mM, reducing viability by over 50 %. However, Apelin-13 treatment mitigated these effects, especially at 2 μg/ml, enhancing cell viability and reducing inflammatory cytokine levels (IL-1β and TNF-α). Apelin-13 also increased anti-inflammatory cytokine levels (IL-10 and TGF-β1) and brain-derived neurotrophic factor (BDNF), indicating its neuroprotective role. Oxidative stress markers, including ROS, AGE, AOPP, DT, T-SH, were significantly elevated by D-Glutamic acid but effectively reduced by Apelin-13. The neuroprotective mechanisms of Apelin-13 involve modulation of cAMP/PKA and MAPK signaling pathways, enhancing BDNF synthesis and suppressing oxidative stress and inflammatory responses. This study is the first to demonstrate the effects of D-Glutamic acid on SH-SY5Y cells. It highlights Apelin-13's potential as a therapeutic agent against excitotoxicity-induced neuronal damage, emphasizing its ability to modulate key molecular pathways involved in inflammation and oxidative stress. Further in-vivo studies are warranted to explore the long-term neuroprotective effects of Apelin-13 in treating neurodegenerative diseases.

Potential Involvement of Apelin/APJ System in Addiction and Neuroprotection Against Drugs of Abuse

Addiction, characterized by compulsive drug-seeking behavior and impaired self-control, remains a significant public health concern. Understanding the neurobiology of addiction is crucial for identifying novel therapeutic targets and further developing effective treatments. Recently, the apelin/APJ system, an emerging signaling pathway, has attracted attention for its involvement in various neuropsychiatric disorders. The cross-talk between the apelin/APJ system and hypothalamic mu opioid signaling, as well as its heterodimerization with kappa opioid receptors (KORs), supports the potential relevance of this system to addiction. Moreover, several protective effects of apelin against various addictive substances, including methamphetamine, morphine, and alcohol, underscore the need for further investigation into its role in substance use disorder. Understanding the contribution of the apelin/APJ system in addiction may offer valuable insights into the underlying neurobiology and pave the way for novel therapeutic interventions in substance use disorders. This review provides a concise overview of the apelin/APJ system, emphasizing its physiological roles and highlighting its relevance to addiction research.

Vanillin derivatives as antiamnesic agents in scopolamine-induced memory impairment in mice

Amnesia is a major health problem prevalent in almost every part of the world specifically in old age peoples. Vanillin analogues have played an important role in the field medicines. Some of them have been documented to be promising inhibitors of cholinesterases and could therefore, be used as antidepressant, anti-Alzheimer and as neuroprotective drugs. In this connection, the present study was designed to synthesize new vanillin analogues (SB-1 to SB-6) of varied biological potentials. The synthesized compounds were investigated as inhibitors against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes and as scavengers of DPPH and ABTS free radicals followed by behavioural antiamnesic evaluation in mice. The compounds; SB-1, SB-3, SB-4 and SB-6 more potently inhibited AChE with IC50 values of 0.078, 0.157, 0.108, and 0.014 μM respectively. The BChE was more potently inhibited by SB-3 with IC50 of 0.057 μM. Moreover, all of the tested compounds exhibited strong antioxidant potentials with promising results of SB-3 against DPPH with IC50 of 0.305 μM, while SB-5 was most active against ABTS with IC50 of 0.190 μM. The in-vivo studies revealed the improvement in memory deficit caused by scopolamine. Y-Maze and new object recognition test showed a considerable decline in cognitive dysfunctions. In Y-Maze test the spontaneous alteration of 69.44 ± 1% and 84.88 ± 1.35% for SB-1 and 68.92 ± 1% and 80.89 ± 1% for SB-3 at both test doses were recorded while during the novel object recognition test the Discrimination Index percentage of SB-1 was more pronounced as compared to standard drug. All compounds were found to be potent inhibitors of AChE, BChE, DPPH, and ABTS in vitro however, SB-1 and SB-3 were comparatively more potent. SB-1 was also more active in reclamation of memory deficit caused by scopolamine. SB-1 and SB-3 may be considered as excellent drug candidates for treating amnesia subjected to toxicological evaluations in other animal models.

Erythropoietin improve spatial memory impairment following methamphetamine neurotoxicity by inhibition of apoptosis, oxidative stress and neuroinflammation in CA1 area of hippocampus

OBJECTIVE

Methamphetamine (METH) is one of the most widely used addictive drugs, and addiction to it is on the rise all over the world. METH abuse has long-term damaging effects that reduce memory and impair cognitive functions. According to studies, the observed effects are strongly related to the nerve cell damage caused by METH, which leads to neurotoxicity. Some of these intra-neuronal events include dopamine oxidation, excitotoxicity, and oxidative stress. Erythropoietin (EPO) is a hormone produced primarily by the kidneys and, in small quantities, by the liver. Studies have shown that EPO exhibits considerable neuroprotective effects. This study aimed to investigate the protective effects of EPO on METH neurotoxicity.

METHODS

Initially, 48 male Wistar rats, weighing 250-300 g, were randomly assigned to four groups: control (n = 12), METH (n = 12), and METH+EPO (2500, 5000 IU/kg/IP- n = 12). METH was injected intraperitoneally at a dose of 40 mg per kg of body weight (four injections of 10 mg every two hours) to induce neurotoxicity. EPO was injected at doses of 2500 and 5000 IU/kg seven days after the last METH administration (ip). Morris water maze test was performed following EPO injection (1 day after the last dose) to assess spatial memory. The brains were removed after the behavioral test, biochemical evaluations and immunohistochemistry (caspase-3 and GFAP) was performed.

RESULTS

The results showed that EPO treatment significantly improved spatial memory impairment (P < 0.01), compared to the METH group, EPO was a significant reduction in malondialdehyde and TNF-α (P < 0.01), as well as an increase in superoxide dismutase (P < 0.05) and glutathione-PX (P < 0.01). Furthermore, EPO treatment significantly reduced the number of GFAP positive cells (P < 0.01) and caspase 3 (P < 0.001) in the hippocampus (CA1 region).

CONCLUSIONS

The study findings suggested that EPO may have great neuroprotective effects on METH neurotoxicity due to its anti-inflammatory, antioxidant, and antiapoptotic properties.

Apelin-13 activates the hippocampal BDNF/TrkB signaling pathway and suppresses neuroinflammation in male rats with cisplatin-induced cognitive dysfunction

It has been established that cisplatin causes neuronal damage and cognitive impairment. However, the mechanism is not sufficiently clear. Apelin-13 is an endogenous peptide with strong neuroprotective effects through the synthesis of neurotrophic factors and suppression of inflammation. The aim of this study was to investigate the role of brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling pathway and the potential inhibitory effects of apelin-13 in the mechanism of cisplatin-induced hippocampal damage and cognitive impairment. Apelin-13 was administered to adult sprague dawley male rats at a dose of 20 nmol/kg every day for 4 weeks, cisplatin was administered at a dose of 5 mg/kg once a week for 4 weeks. The spatial and recognition memory tests of the rats were performed on the 5th week. BDNF and the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels were measured by ELISA in hippocampal homogenates. Pyramidal neuron and glial cell damage in the hippocampal CA1, CA3 and dentate gyrus (DG) were analyzed histologically. TrkB activity in the hippocampus was determined by immunohistochemical methods. Cisplatin impaired spatial and recognition memory in rats, while apelin-13 improved spatial memory but did not affect recognition memory. Cisplatin suppressed BDNF in the hippocampus while increased IL-1β and TNF-α. In contrast, apelin-13 administration increased BDNF but significantly suppressed TNF-α and IL-1B. Cisplatin caused pyramidal neuron and glial cell damage in CA1, CA3 and DG. In the cisplatin + apelin-13 group, however, pyramidal neuron and glial cell damage was less than those without apelin-13. Cisplatin increased TrkB activity in the hippocampus, which was counteracted by apelin-13. In conclusion, apelin-13 reduced the cisplatin-induced cognitive deficiency, by suppressing inflammation and stimulating the synthesis and activation of neurotrophic factors in hippocampal tissue.