Neuroprotective activity of green synthesized silver nanoparticles against methamphetamine-induced cell death in human neuroblastoma SH-SY5Y cells.

The present study aimed to investigate the neuroprotective activity of the black peel pomegranate extract, and silver nanoparticles (AgNPs) biosynthesized using the extract. We pretreated the human neuroblastoma SH-SY5 cells with the extract and AgNPs and evaluated the neuroprotective activity of these agents against methamphetamine (Meth) cytotoxicity. The NPs were spherical with 19 ± 8 nm size, - 28 mV surface charge, and 0.20 PDI. Meth killed the cells by increasing proapoptotic (Bax, PTEN, AKT, PI3K, NF-κB, P53, TNF-α, Cyt C, and Cas 3) and decreasing the antiapoptotic genes (Bcl-2) expression. Exposure to Meth caused DNA fragmentation and increased the intercellular ROS and malondialdehyde (MDA) levels while reducing the mitochondrial membrane potential (MMP). A 4-h pretreatment of the cells with the extract and AgNPs could retain the viability of the cells above 80% by increasing the Bcl-2 expression up to fourfold and inhibiting the cell death pathways. ROS, MDA, and MMP levels in the pretreated cells were close to the control group. The percentage of necrosis in cells pretreated with the extract and AgNPs declined to 32% and 8%, respectively. Our promising findings indicated that AgNPs could reduce Meth-induced oxidative stress and prevent necrotic and apoptotic cell death by regulating related genes' expression.

Estrogen receptor agonists induce anti­edema effects by altering α and ß estrogen receptor gene expression.

The present study aimed to examine whether the attenuation of estrogen receptor expression is prevented by propyl pyrazole triol (PPT), an agonist for estrogen receptor α (ERα) or and diarypropiolnitrile (DPN), an agonist for estrogen receptor ß (ERß) after traumatic brain injury (TBI). The tests performed on ovariectomized female Wistar rats included sham group, vehicle group, and treated groups: PPT, DPN, and PPT+DPN 30 minutes after TBI. Blood­brain barrier (BBB) disruption and brain water content were estimated. RT­PCR and\r\nwestern blotting were utilized to evaluate ESR1 and ESR2 gene and protein expression. The data indicated that PPT, DPN, and PPT+DPN attenuated TBI­induced brain edema. Also, BBB disruption after TBI was prevented in PPT, DPN, and PPT+DPN­treated TBI animals. Estrogen agonist­treated animals showed a significant elevation in Esr1 mRNA and protein expression levels in the brain tissue of TBI rats. In addition, the data indicated a significant elevation of Esr2 mRNA and protein expression levels in the brain tissue of estrogen agonist­treated TBI rats. The data shows that both ESR1 and ESR2 agonists can enhance ER mRNA and protein levels in TBI animals' brain. It appears that this effect contributes to the neuroprotective function of ER agonists.

Effects of maternal separation on nicotine-induced conditioned place preference and subsequent learning and memory in adolescent female rats.

Adverse early life experiences can potentially increase risk for drug abuse later in life. However, little research has been conducted studying the effects of maternal separation (MS), an experimental model for early life stress, on the rewarding effects of nicotine. Cognitive function may be affected by MS. So, we also investigated whether nicotine administration affect spatial learning and memory in MS adolescent female rats. Rat pups were subjected to daily MS for 15min (MS15) or 180min (MS180) during the first 2 weeks of life or reared under normal animal facility rearing (AFR) conditions. The place preference test was performed with nicotine (0.6mg/kg,s.c.) or vehicle over a period of 6 conditioning trials during adolescence. Spatial learning and memory performance was evaluated by using Morris water maze (MWM). In our study, adolescent female rats exposed to MS180 shown a significantly greater preference for a nicotine-paired compartment during the testing phase than the MS15 group. Nicotine altered the MS-induced spatial learning defects in the MS180 group. These findings suggest that MS may increase sensitivity to the rewarding effects of nicotine and also it is possible to suggest that nicotine administration may influence learning dysfunction induced by MS in adolescent female rats.

Effects of pulsed electromagnetic field on intervertebral disc cell apoptosis in rats.

Despite numerous studies on pulsed electromagnetic field (PEMF) application, its effects of PEMF on intervertebral disc (IVD) have not yet been investigated in vivo. Accordingly, the effects of PEMF upon IVD in rats were evaluated through molecular surveys. Rats were divided into six groups: Group I and II were exposed to low and high frequency of PEMF (LF and HF, respectively). Group III and IV underwent induced disc degeneration and were exposed to low and high frequency of PEMF (LF/IDD and HF/IDD, respectively). Group V underwent induced disc degeneration (IDD), and group VI was control. The values of caspase 3, Bax, Bcl-2 and ß-actin band density, as cell apoptotic markers, were obtained from band densitometry. Our results showed that the value of cleaved caspase-3 of cells and Bax/Bcl-2 ratio in IDD group increased significantly compared to the control group (p < 0.001). The value of cleaved caspase-3 and Bax/Bcl-2 ratio decreased significantly in LF/IDD and HF/IDD groups compared to IDD group (p < 0.05). No significant increase was seen in the cell apoptotic markers in the groups just exposed to PEMF compared to the control group. There was also no significant decrease in the Bax/Bcl-2 ratio in HF/IDD and LF/IDD groups compared to the control group. These data suggest that PEMF attenuates degenerative processes in rat's intervertebral discs and has no effect on normal discs. Regulations of the expression of apoptotic proteins may be one of the mechanisms by which PEMF is effective in reduce disc degeneration.

Involvement of hypothalamic pituitary adrenal axis on the nifedipine-induced antinociception and tolerance in rats.

Nifedipine, a calcium channel blocker, can modulate the nociceptive threshold. However, the underlying mechanism, especially the role of HPA axis, on this effect has still not been elucidated. In the present study we investigated the analgesic effect of nifedipine in intact and adrenalectomized (ADX) male rats and we also measured the effect of nifedipine on HPA function. The Tail-Flick test was used to assess the nociceptive threshold before and 15, 30, 60, 90, and 120 min after drug administration. Corticosterone level was measured by radioimmunoassay as a marker of HPA function. Our results showed that in intact and sham operated animals, administration of 10 mg/kg nifedipine induces an antinociceptive effect. But at the dosage of 2 and 5 mg/kg animals do not exhibit this effect. With repeated injections, its analgesic effect was decreased, a phenomenon prevented by adrenalectomy. Acute administration of nifedipine produced significant decrease in plasma corticosterone level. In ADX animals, had a potent antinociceptive effect nifedipine at high dosage (10 mg/kg) as well as at lower dosage (5 mg/kg) that reversed with corticosterone replacement. In conclusion, the results of our study show that the elimination of HPA function through adrenalectomy potentiates the antinociceptive effect of nifedipine and attenuates its analgesic tolerance. Both effects are reversed by corticosterone replacement.