Novel Neuroprotective Potential of Crocin in Neurodegenerative Disorders: An Illustrated Mechanistic Review.

Neurodegenerative disorders are characterized by mitochondrial dysfunction and subsequently oxidative stress, inflammation, and apoptosis that contribute to neuronal cytotoxicity and degeneration. Recent studies reported that crocin, a carotenoid chemical compound common in crocus and gardenia flowers, has protective effects in neurodegenerative disorders due to its anti-oxidative, anti-inflammatory, and anti-apoptotic properties in the nervous system. This article reviews the new experimental, clinical, and pharmacological studies on the neuroprotective properties of crocin and its potential mechanisms to modulate metabolic oxidative stress and inflammation in neurodegenerative disorders.

Pharmacological evidence for lithium-induced neuroprotection against methamphetamine-induced neurodegeneration via Akt-1/GSK3 and CREB-BDNF signaling pathways.

OBJECTIVES: Neurodegeneration is an outcome of Methamphetamine (METH) abuse. Studies have emphasized on the neuroprotective properties of lithium. The current study is designed towards evaluating the role of Akt-1/GSK3 and CREB-BDNF signaling pathways in mediating lithium neuroprotection against METH-induced neurodegeneration in rats. MATERIALS AND METHODS: Sixty adult male rats were randomly divided into five groups: control group (received 0.7 ml normal saline per rat for 28 days), METH group (given 10 mg/kg of METH intraperitoneally for 28 days), groups 3, 4, and 5 (given METH (10 mg/kg) and lithium (75, 150, and 300 mg/kg intraperitoneally, individually for 28 days). Morris water maze (MWM) was used to assess mental functions. In addition to hippocampal neurodegeneration, Brain-derived neurotrophic factor (BDNF), cAMP response element binding (CREB), Glycogen synthase kinase 3 (GSK3), and Protein kinase B (Akt-1) were assessed in isolated hippocampus. RESULTS: METH abuse caused marked disorders in learning and memory that were dramatically improved with various doses of lithium. Furthermore, METH increased lipid peroxidation and the levels of oxidized form of interleukin 1 beta (IL-1ß), glutathione (GSSG), Bax, tumor necrosis factor alpha (TNF-α), and GSK3, while attenuating the extent of glutathione (reduced form (GSH)), P-CREB, Bcl-2, BDNF, and Akt-1 in the hippocampus. Moreover, METH declined superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) activity in the hippocampus. Conversely, lithium attenuated METH-stimulated apoptosis, oxidative stress, and inflammation; while improving the extent of BDNF and P-CREB. CONCLUSION: Probably lithium possesses neuroprotection against METH-stimulated neurodegeneration in the hippocampus via Akt-1/GSK3ß and CREB/BDNF signaling pathways.

Protective role of metformin against methamphetamine induced anxiety, depression, cognition impairment and neurodegeneration in rat: The role of CREB/BDNF and Akt/GSK3 signaling pathways.

BACKGROUND: Methamphetamine is a neuro-stimulant with neurodegenerative effects, and ambiguous mechanism of action. Metformin is an antidiabetic agent with neuroprotective properties but not fully understood mechanisms. The present study investigated the molecular basis of metformin neuroprotection against methamphetamine-induced neurodegeneration. BRIEF METHOD: Sixty adult male rats were randomly divided into six groups: group 1 (received normal saline), group 2 (received 10 mg/kg of methamphetamine) and groups 3, 4, 5 and 6 [received methamphetamine (10 mg/kg) plus metformin (50, 75, 100 and 150 mg/kg) respectively]. Elevated Plus Maze (EPM), Open Field Test (OFT), Forced Swim Test (FST), Tail Suspension Test (TST) and Morris Water Maze (MWM) were used to assess the level of anxiety, depression and cognition in experimental animals. Also animals' hippocampus were isolated and oxidative stress and inflammatory parameters and expression of total and phosphorylated forms of cAMP response element binding (CREB), brain-derived neurotrophic factor (BDNF), protein kinase B (Akt) and glycogen synthase kinase 3 (GSK3) proteins were evaluated by ELISA method. RESULTS: According to the data obtained, methamphetamine caused significant depression, anxiety, motor activity disturbances and cognition impairment in experimental animals. Metformin, in all used doses, decreased methamphetamine induced behavioral disturbances. Also chronic administration of methamphetamine could increase malondialdehyde (MDA), tumor necrosis factor-Alpha (TNF-α) and interleukine-1 beta (IL-1ß) in rats, while caused reduction of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities. Metformin, especially in high doses, could prevent these malicious effects of methamphetamine. Also Metformin could activate CREB (both forms), BDNF and Akt (both forms) proteins' expression and inhibited GSK3 (both forms) protein expression in methamphetamine treated rats. SIGNIFICANCE: According to obtained data, metformin could protect the brain against methamphetamine-induced neurodegeneration probably by mediation of CREB/BDNF or Akt/GSK3 signaling pathways. These data suggested that CREB/BDNF or Akt/GSK3 signaling pathways may have a critical role in methamphetamine induced neurotoxicity and/or neuroprotective effects of metformin.