Roles of the nucleus accumbens [shell] in the acquisition and expression of morphine-induced conditioned behavior in freely moving rats

The nucleus accumbens [NAc] is a part of the rewarding cortico mesolimbic dopamine [DA] pathway. This is a heterogeneous structure divided in two sub regions termed core and shell. DA function in the NAc is critical for goal oriented behaviors, including those motivated by drug and brain stimulation reward. In the conditioned-place preference [CPP] paradigm, a test assessing animal's ability to associate drug induced effects with environmental cause to quantify drug reward for example morphine. In the present study, we investigated the influence of electrical stimulation with different current intensities on [25 and 100 micro A] with and without an effective dose of morphine [0.5 and 5 mg/kg] on CPP. Subcutaneous administration of morphine 5 mg/kg produced significant CPP in comparison with saline group. Our findings also showed that electrical stimulation of NAc [100 micro A] significantly [P < 0.01] suppressed morphine-induced CPP that reveals impaired learning and memory formation in the process of conditioning. We found that morphine induced CPP can be successfully suppressed by current intensity [100 micro A]. It was probably due to decreasing of dopamine contents and its metabolites in the NAc. Current intensity [100 micro A] in combination with ineffective dose of morphine [0.5 mg/kg] increased morphine induced CPP probability via the prove reward system. Since stimulation of dopaminergic neurons increases tendency to dependence to morphine, therefore in the present study, the stimulation of the NAc suppressed morphine induced CPP that this shows impairment of learning and memory formation

Effects of silver nano-particles on sperm parameters, number of Leydig cells and sex hormones in rats

Nano-particles are extensively employed in most industries. Several studies have been started to explore the probable detrimental effects of nano-particles on human reproduction. However, there is insufficient and controversially evident of effects of silver nano-particles on sperm parameters and other reproductive indices. Investigation of the effects of silver nano-particles on sperm parameters, sex hormones and Leydig cells in rat as an experimental model. In this experimental study, 75 male prepubertal Wistar rats were categorized in five groups including control group and 4 experimental groups [n=15 in each group]. The rats in the experimental groups were fed silver nano-particles [60 nm in dimension] with concentrations of 25, 50, 100, and 200 mg/kg/day. After 45 days [about one duration of spermatogenesis in rat], samples of blood were taken from the rats for testosterone, leuteinizing hormone [LH], and follicle stimulating hormone [FSH] assessments. Afterwards, the epididymis and the testis of each rat were dissected for analyzing sperm parameters and Leydig cells. The results demonstrated a statistically significant reduction in number of Leydig cells in experimental groups compared to control one. In addition, the data showed a reduction in testosterone and a rise in LH level which was more obvious in high doses [p<0.05]; however, FSH level showed a reduction but it was not statistically significant. A significant decrease was also found in sperm motility and normal sperm morphology in the experimental groups compared to the control one. Our results demonstrated that silver nano-particles, in addition to interruption in functions of sex hormones, can diminish the number of Leydig cells and sperm parameter indices. It should be noted that the effects of nano-particles on reproductive indices are dose-dependent

Protective role of recombinant human erythropoietin in kidney and lung injury following renal bilateral ischemia-reperfusion in rat model

Acute kidney injury [AKI] has been recognized as one of the most complex clinical complications in modern medicine, and ischemia/reperfusion [I/R] injury is well-known as a main reason of AKI. In addition, AKI leads to important systemic consequences such as acute lung injury. This study was designed to investigate the role of erythropoietin [EPO] on kidney function makers and tissue damage; and lung endothelial permeability and lung water content [LWC] in bilateral renal I/R injury model in rats. Male Wistar rats were randomly divided into three groups of sham, I/R, and I/R treated with EPO [I/R + EPO] groups. The I/R and I/R + EPO groups were subjected to bilateral renal I/R injury; however, only the I/R + EPO group received EPO [500 IU/kg, i.p.] 2 h before ischemia surgery, and the same dose was continued once a day for 3 days after ischemia. The sham group underwent a surgical procedure without ischemia process. The blood urea nitrogen [BUN] and serum creatinine [Cr] levels, kidney tissue damage score [KTDS], and kidney weight [KW] per 100 g body weight significantly increased in I/R group [P < 0.05]. EPO administration decreased levels of BUN and Cr significantly [P < 0.05], and KTDS and KW insignificantly [P = 0.1]. No significant differences in kidney and serum levels of malondialdehyde, and lung vascular permeability and LWC were observed between the groups. The serum and kidney levels of nitrite were not significantly different between I/R and sham groups; however, administration of EPO increased the renal level of nitrite [P < 0.05]. EPO protected the kidney against I/R injury; however, it may not protect the lung tissue from the damage induced by renal I/R injury in rats

N-acetylcysteine prevents kidney and lung disturbances in renal ischemia/ reperfusion injury in rat

One of the most common causes of acute kidney injury [AKI] is kidney ischemia/reperfusion injury [IRI]. The distant organ injury such as acute lung injury is one of the side effects of AKI or kidney IRI. In this study, we performed bilateral renal IRI in rats and the protective role of N acetylcysteine [NAC] in kidney and lung was investigated. Rats [n = 30] were randomly assigned to four experiment groups. The group 1 was assigned as sham operated group. Before kidney IRI performance, the others groups were treated with saline [group 2], 150 mg/kg [group 3] or 500 mg/kg [group 4] of NAC, and the treatment were continued daily after IRI for next 3 days. At day 3, the all groups' animals were subjected for the measurements. The serum level of blood urea nitrogen [BUN] and creatinine [Cr] in the control group increased significantly [P < 0.05], and administration of NAC [150 mg/kg] decreased the serum levels of Cr and BUN. However, only the serum level of Cr decreased significantly [P < 0.05]. NAC did not improve kidney weight and damage; however, its low dose [150 mg/kg] attenuated the lung injury score [P < 0.05] when compared with the control group. No significant differences were observed in lung water content and endothelial permeability, serum levels of malondialdehyde and nitrite between the groups. Low dose of NAC as a protectant agent may protect the kidney function and lung tissue damage after kidney IRI