Prenatal Stress-induced Spatial Memory Deficit in a Sex-specific Manner in Mice: A Possible Involvement of Hippocampal Insulin Resistance.

Introduction: In the present study, the effects of prenatal stress on spatial learning and memory deficit and its relationship with hippocampal insulin resistance were examined in male and female offspring. Methods: Female NMRI mice were mated with males overnight, and the 0-day of pregnancy was detected (Gestational day 0-GD0). The pregnant mice were then randomly divided into stress and control groups. The stress group received stress from the GD0 to GD10. On post natal day 30 (PND30), the offspring were divided into 4 subgroups, namely: male-control, female-control, male-stress, and female-stress. Barnes maze method was used for spatial learning evaluation. Plasma cortisol and insulin levels were measured at the beginning of the experiments. At the end of the experiments, the animals' brains were removed, and their hippocampus was extracted. The hippocampus was homogenized, and its insulin and insulin-receptor contents were evaluated. Results: The stressed animals needed more time for reaching to target hole. In addition, they spend more distance to find the target hole, which was more pronounced in the male offspring. Both plasma and hippocampal insulin content were reduced in the stressed groups. Moreover, the hippocampal insulin receptors protein was reduced in the stressed animals. There was a positive relationship between plasma and hippocampal content and memory deficit in the stressed groups. Conclusion: These results indicated that prenatal stress could induce spatial learning and memory deficit in offspring, which is associated with plasma and hippocampal insulin and receptor content reduction (hippocampal insulin resistance) in these animals. Highlights: Maternal stress is very harmful for fetus.The effect of stress is significant during the early days of gestation.This effect is due to several hormonal and neuronal disturbances including Insulin resistance.The effects of stress on the fetus is gender dependent. Plain Language Summary: The possible effectiveness of prenatal stress on learning and memory in neonates and also the changes in hippocampus as of essential part of the brain involved in learning and memory. We found that prenatal stress can reduce the insulin effects in hippocampus and it may be the main cause of stress on neonatal memory deficits.

Protective effect of apigenin on ethylene glycol-induced urolithiasis via attenuating oxidative stress and inflammatory parameters in adult male Wistar rats.

AIMS: Apigenin (4',5,7-trihydroxyflavone) is one of the subclasses of flavonoids and has various pharmacological effects. The present work was carried out to study the effect of apigenin on ethylene glycol-induced kidney damage in male Wistar rats. MAIN METHODS: We evaluated the effects of apigenin orally administrated in normal and urolithiatic rats. Animals were assigned to nine groups in random: normal control; apigenin alone (0.005, 0.01, and 0.02 g/kg bw); urolithiatic control (0.75% ethylene glycol and 1.0% ammonium chloride in drinking water); apigenin (0.005, 0.01, and 0.02 g/kg bw) plus ethylene glycol and ammonium chloride; and cystone (0.75 g/kg bw) plus ethylene glycol and ammonium chloride. At the end of 28th day of treatment, animals were sacrificed for biochemical and histopathological assays. KEY FINDINGS: Our results indicated that the apigenin treatment decreased the formation of urinary stones in urolithiatic rats. Also, apigenin reduced the generation of malondialdehyde and enhanced antioxidant enzymes activities in the kidney homogenate of rats. It also caused a significant decrease in the calcium oxalate crystals numbers in urinary sample of rats with ethylene glycol-induced hyperoxaluria. These findings were supported by histopathological examinations. SIGNIFICANCE: Based on the results obtained, apigenin attenuate ethylene glycol-related kidney damage in male Wistar rats. Although the underlying mechanism of apigenin effect has not been determined, reduction of urinary levels of stone-producing constituents, antioxidant activities, and inhibition of TGF-ß signaling may be involved.

Chlorogenic acid induces 4T1 breast cancer tumor's apoptosis via p53, Bax, Bcl-2, and caspase-3 signaling pathways in BALB/c mice.

Despite all the new treatments, metastatic breast cancer (BC) causes many deaths. Chlorogenic acid (CGA) is a polyphenol compound with various pharmacological traits, such as anticancer properties. Targeting apoptotic death pathways has been propounded as the most effective therapeutic method in various cancers. In the current study, apoptotic agents such as p53, Bax, Bcl-2, and caspase-3 have been investigated. The experimental groups included saline, BC, CGA, protective (PR), and treatment (TM) groups. First, 4T1 mouse BC was established and then the effects of treatment with CGA were investigated through measurement of tumor weight and volume, metastatic nodules, liver biochemical tests, hematoxylin and eosin (H&E), immunohistochemistry (IHC) staining, and real-time reverse transcription-polymerase chain reaction (RT-PCR) in experimental groups. The findings showed that CGA reduced tumor weight and volume in the PR group (P < .05) and in the TM group (P < .001). Surprisingly, it eliminated the tumors in the TM group. Metastatic nodules in the PR and TM groups were significantly reduced as compared with the BC group (P < .001). The evaluation by H&E staining showed cell apoptosis in both the PR and TM groups. The results of real-time RT-PCR showed that CGA therapy increased the expression ratio of Bax/Bcl-2 (P < .001 and P < .05, respectively) and the expression of p53 (P < .001 and P < .05, respectively) and caspase-3 genes (P < .01) in the PR and TM groups. The IHC data regarding the Bax/Bcl-2 ratio confirmed the other results (P < .001). The findings demonstrate that CGA plays a significant role in the induction of apoptosis and the treatment of 4T1 BC tumors in BALB/c mice.

Chlorogenic acid inhibits growth of 4T1 breast cancer cells through involvement in Bax/Bcl2 pathway.

OBJECTIVE(S): Chlorogenic acid is an herbal compound with various effects such as antiviral, antioxidant, and anticancer effect with low toxicity, which inhibits cell proliferation. Clinical studies had shown that chlorogenic acid has a positive effect on the different types of cancers treatment. Hence, this study evaluates chlorogenic acid effects on 4T1 breast cancer cells. MATERIALS AND METHODS: In this study, cell proliferation was measured using an 3-(4,5-methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay (MTT) on 4T1 cells. Afterwards, other assays like P53, Caspase-3 proteins expression and Annexin V/PI were detected by flow cytometry. Also; Bax and Bcl-2 were carried out by immunocytochemistry. RESULTS: 200 µM of chlorogenic acid concentration showed the highest level of cytotoxicity toward 4T1 cells. Percentage of cell viability data were significant in 100 µM (P < 0.05) and 150, 200 µM (P < 0.001) doses. The evaluation using Annexin V/PI showed cell apoptosis in 100 µM (P < 0.05), 150 µM (P < 0.01), and for 200 µM (P < 0.05 and P < 0.01). Immunocytochemistry results showed the upregulation of Bax and also the downregulation of Bcl-2 in 4T1 cells treated with chlorogenic acid (P < 0.001). The expression level of P53 and caspase-3 increased during treatment with chlorogenic acid in the 4T1 cells (P < 0.001). CONCLUSION: Our findings demonstrated that chlorogenic acid plays a notable role on apoptosis inducing in the 4T1 cells through regulation of apoptotic proteins.

Protective effects of 5-HT1A receptor antagonist and 5-HT2A receptor agonist on the biochemical and histological features in a rat model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder and neuropathologically characterized by the aggregation of amyloid-beta (Aß) plaques, neurofibrillary tangles, enhanced oxidative stress and neurodegeneration. Involvement of serotonergic systems in AD has been supposed and it is suggested that serotonin receptors modulation may provide a novel therapeutic target for AD. This study aimed at investigating the protective effect of NAD-299 (the selective 5-HT1A receptor antagonist) and TCB-2 (the potent5-HT2A receptor agonist) on the hippocampal oxidative stress biomarkers and the number of intact neurons in streptozotocin (STZ)-induced Alzheimer's disease in rats. Fifty adult male Wistar rats weighing 250-300 g were divided into five groups: sham, STZ-treated, STZ + NAD-299 (5 µg/1 µl icv), STZ + TCB-2 (5 µg/1 µl icv) and STZ + NAD-299 (5 µg/0.5 µl icv) +TCB-2 (5 µg/0.5 µl icv). At the end of the study, the rats were weighed, then hippocampal oxidative stress markers [total antioxidant capacity (TAC), malondialdehyde (MDA), the total thiol group (TTG), and DNA damage] were measured. In addition, the number of intact neurons in the CA1 area of the hippocampus was determined using hematoxylin and eosin staining. The results showed that icv injection of STZ reduced hippocampal TAC, TTG levels and intact pyramidal cells and increased DNA damage and MDA levels in the hippocampus of STZ-treated rats. Icv administration of NAD-299, TCB-2, and NAD-299+TCB-2 increased TAC and TTG contents and hippocampal intact neurons and reduced hippocampal DNA damage, MDA levels in icv-STZ treated rats. Moreover, there was no significant difference in weight changes among the experimental groups. According to the obtained results, it is suggested that 5-HT1A receptor antagonist (NAD-299) and 5-HT2A receptor agonist (TCB-2) can reduce oxidative stress and neuronal loss in a rat model of AD and may prevent the AD progression.

The effect of NAD-299 and TCB-2 on learning and memory, hippocampal BDNF levels and amyloid plaques in Streptozotocin-induced memory deficits in male rats.

RATIONALE: Alzheimer's disease (AD) is the most common form of dementia characterized by a progressive decline in cognitive function. The serotonergic system via the 5-HT1A receptor and 5-HT2A receptor is proposed to affect the cognitive process. OBJECTIVE: In the present study, the effects of NAD-299 (5-HT1AR antagonist) and TCB-2 (5-HT2AR agonist) on learning and memory processes, hippocampal brain-derived neurotrophic factor (BDNF) levels, neuronal necrosis, and Aß plaque production have been investigated on the intracerebroventricular (icv) injection of streptozotocin (STZ)-induced memory deficits in rats. METHODS: Fifty-four adult male Wistar rats (250-300 g) were divided into six groups (n = 9 in each group): control, sham-operated, AD (icv-STZ (3 mg/kg, 10 µl)), AD+NAD-299 (5 µg/1 µl icv for 30 days), AD+TCB-2 (5 µg/1 µl icv for 30 days), and AD+NAD-299 + TCB-2 (NAD-299 (5 µg/0.5 µl icv) and TCB-2 (5 µg/0.5 µl icv) for 30 days). Following the treatment period, rats were subjected to behavioral tests of learning and memory. Then, hippocampal BDNF, amyloid-beta (Aß) plaque, and neuronal loss were determined by ELISA Kit, Congo red staining, and Nissl staining, respectively. RESULTS: The results of behavioral tests showed that icv-STZ injection decreased the discrimination index in the novel object recognition (NOR) test. In the passive avoidance learning (PAL) task, icv-STZ injection significantly decreased step-through latency (STLr) and increased time spent in dark compartment (TDC). Treatment with NAD-299, TCB-2, and NAD-299 + TCB-2 attenuated the STZ-induced memory impairment in both NOR and PAL tasks. icv-STZ induced a decrease in hippocampal BDNF levels and increased Aß plaques production in the brain, whereas treatment with NAD-299, TCB-2, and NAD-299 + TCB-2 reduced Aß plaques in the brain and increased the hippocampal BDNF level. Results of Nissl staining showed that icv-STZ injection increased neuronal loss in the hippocampus, while treatment with NAD-299, TCB-2, and NAD-299 + TCB-2 reduced hippocampal neurodegeneration. CONCLUSION: These findings suggest that 5-HT1AR blockade by NAD-299 and 5-HT2AR activation by TCB-2 improve cognitive dysfunction in icv-STZ-treated rats, and these drugs may potentially prevent the progression of AD.

Effect of selenium on testicular damage induced by varicocele in adult male Wistar rats.

PROJECT: Varicocele is an abnormal tortuosity and distension of the veins of the pampiniform plexus in the spermatic cord. It is the most common surgically correctable cause of male infertility. Several studies have revealed the effects of increased oxidative stress on serum, semen, and testicular tissues in patients with varicocele or in animal models. The aim of this study was to investigate the effects of sodium selenite on testicular damage induced by experimental left varicocele in male Wistar rats. PROCEDURE: In the present study, the effects of oral administration of sodium selenite (at doses of 0.05, 0.1, 0.2, and 0.4mg/kg bw) were assessed in normal and varicocelized rats. RESULTS: The varicocelized control rats showed decrease in sperm quality parameters, decreased activity of testes CAT, GPX and SOD, increased levels of MDA, and damage in testicular architecture. Administration of sodium selenite significantly reduced these changes to nearly normal levels, but did not change these parameters in normal rats. Histopathological studies further confirmed the protective effects of sodium selenite on varicocele-induced testicular damage in rats. Administrations of sodium selenite did not change these parameters in normal rats. CONCLUSIONS: Taken together, the results of this study suggest that sodium selenite treatment may have beneficial effect on the testes of varicocelized rats.

The neuroprotective potential of sinapic acid in the 6-hydroxydopamine-induced hemi-parkinsonian rat.

Parkinson's disease (PD) is a neurodegenerative movement disorder due to selective loss of dopaminergic neurons of mesencephalic substantia nigra pars compacta (SNC) with debilitating motor symptoms. Current treatments for PD afford symptomatic relief with no prevention of disease progression. Due to the antioxidant and neuroprotective potential of sinapic acid, this study was conducted to evaluate whether this agent could be of benefit in an experimental model of early PD in rat. Unilateral intrastriatal 6-hydroxydopamine (6-OHDA)-lesioned rats were pretreated p.o. with sinapic acid at doses of 10 or 20 mg/kg. One week after surgery, apomorphine caused significant contralateral rotations, a significant reduction in the number of Nissl-stained and tyrosine hydroxylase (TH)-positive neurons and a significant increase of iron reactivity on the left side of SNC. Meanwhile, malondialdehyde (MDA) and nitrite levels in midbrain homogenate significantly increased and activity of superoxide dismutase (SOD) significantly reduced in the 6-OHDA-lesioned group. In addition, sinapic acid at a dose of 20 mg/kg significantly improved turning behavior, prevented loss of SNC dopaminergic neurons, lowered iron reactivity, and attenuated level of MDA and nitrite. These results indicate the neuroprotective potential of sinapic acid against 6-OHDA neurotoxicity that is partially due to the attenuation of oxidative stress and possibly lowering nigral iron level.

Hepatoprotective effect of manganese chloride against CCl4-induced liver injury in rats.

The aim of the present study is to evaluate the protective effect of manganese chloride against carbon tetrachloride (CCl4)-induced liver injury in rats. Manganese chloride (0.001, 0.01, 0.05 and 0.1 g/kg bw) was administered intragastrically for 28 consecutive days to male CCl4-treated rats. The hepatoprotective activity was assessed using various biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT) and superoxide dismutase (SOD). Histopathological changes in the liver of different groups were also studied. Administration of CCl4 increased the serum ALT, AST, ALP and GGT but decreased SOD levels in rats. Treatment with manganese chloride significantly attenuated these changes to nearly normal levels. The animals treated with manganese chloride have shown decreased necrotic zones and hepatocellular degeneration when compared to the liver exposed to CCl4 intoxication alone. Thus, the histopathological studies also supported the protective effect of manganese chloride. Therefore, the results of this study suggest that manganese chloride exerts hepatoprotection via promoting antioxidative properties against CCl4-induced oxidative liver damage.

Magnesium attenuates carbon tetrachloride-induced hepatic injury in rats.

In the present study, we investigated the protective effects of magnesium sulfate (MgSO4) against carbon tetrachloride (CCl4)-induced liver damage in rats. MgSO4 (0.001, 0.01, 0.05 and 0.1 Mg(2+) g/kg b.wt.) was administered intragastrically for 28 consecutive days to male, CCl4-treated rats. The hepatoprotective activity was assessed using various biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT) and superoxide dismutase (SOD) activity. Histopathological changes in the liver, of different groups were also studied. Administration of CCl4 increased serum ALT, AST, ALP and GGT, but decreased liver SOD activities in rats. Treatment with MgSO4 significantly attenuated these changes to nearly normal levels. The animals treated with MgSO4 showed decreased necrotic zones and reduced hepatocellular degeneration when compared to liver exposed to CCl4 alone. Hepatic damage was reduced in MgSO4-treated rats. Thus, our results suggest that MgSO4 has potential for the treatment of liver damage resulting from chemical intoxication.

Hepatoprotective effects of pantothenic acid on carbon tetrachloride-induced toxicity in rats.

The present study was undertaken to investigate the hepatoprotective effect of pantothenic acid on CCl4-induced liver damage. Male Wistar rats were orally treated with pantothenic acid (0.005, 0.01, 0.025, 0.05 and 0.1 g/kg) daily, with administration of CCl4 (1 mL/kg, 50 % CCl4 in olive oil) twice a week for 28 days. The effect of pantothenic acid on serum markers (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and γ-glutamyltransferase) was measured in CCl4-induced hepatotoxicity in rat. Further, the effects on enzymatic antioxidant (superoxide dismutase) were estimated in the liver samples. CCl4 challenge not only elevated the serum marker enzyme activities but also suppressed hepatic antioxidative defense system including superoxide dismutase. The biochemical observations were supplemented with histopathological examination of rat liver sections. Histopathological examination of livers showed that pantothenic acid reduced fatty degeneration, cytoplasmic vacuolization and necrosis in CCl4-treated rats. Therefore, pantothenic acid may be an effective hepatoprotective agent and viable candidate for treating hepatic disorders and other oxidative stress-related diseases.

Reduction of metabolic and behavioral signs of acute stress in male Wistar rats by saffron water extract and its constituent safranal.

CONTEXT: Saffron extract can inhibit the metabolic disorders induced by stress but the mechanism of action of saffron extract in the central nervous system is not clear. OBJECTIVE: The present research investigated the effects of saffron water extract and its constituent, safranal on the behavioral and metabolic signs induced by electroshock stress in male Wistar rats (W: 250-300 g). MATERIALS AND METHODS: Dried saffron material and maceration method was used for extraction. Animals received intra-amygdala (1, 5, and 10 µg/rat) or intraperitoneal (1, 5, and 10 mg/kg) administration of the extract, safranal (Fluka, Germany), or saline 5 or 30 min before stress induction, respectively. RESULTS: The result showed that stress elevated the corticosterone plasma (115 nmol/L) concentration in the control and intra-amygdala (1, 5, and 10 µg/rat)-treated groups but not in groups that received extract or safranal (55 nmol/L) intraperitoneally (1, 5, and 10 mg/kg). Moreover, anorexia was reduced only in groups that received the extract (1, 5, and 10 mg/kg) or safranal (1, 5, and 10 mg/kg) intraperitoneally (50 sec). Stress increased sniffing, rearing, locomotion, and coping time, which were decreased by intraperitoneal (1, 5, and 10 mg/kg) but not by intra-amygdala (1, 5, and 10 µg/rat) administration of saffron extract and safranal. DISCUSSION AND CONCLUSION: The results revealed that saffron water extract and safranal had an important impact on the reduction of both metabolic and behavioral signs of stress in male Wistar rats. Moreover, the involvement of the amygdala in this observation can be ruled out.

Protective effects of sodium molybdate on carbon tetrachloride-induced hepatotoxicity in rats.

Molybdenum is an essential trace micronutrient element that plays an important role in animal and plant physiology. Molybdenum is a constituent of at least three mammalian metalloflavoproteins: xanthine oxidase, aldehyde oxidase and sulphite oxidase. In the present study, the hepatoprotective potential of sodium molybdate was investigated against carbon tetrachloride (CCl(4))-induced liver damage in rats. Administration of CCl(4) increased the serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase levels in rats and reduced levels of the antioxidant enzymes superoxide dismutase and catalase in the liver. Treatment with sodium molybdate significantly attenuated these changes to nearly undetectable levels. The histopathological changes induced by CCl(4) were also significantly attenuated by sodium molybdate treatment. Therefore, the results of this study suggest that sodium molybdate can protect the liver against CCl(4)-induced oxidative damage in rats, and this hepatoprotective effect might be attributable to its modulation of detoxification enzymes and/or its antioxidant and free radical scavenger effects.

Acute effects of vinegar intake on some biochemical risk factors of atherosclerosis in hypercholesterolemic rabbits.

BACKGROUND: Exaggerated postprandial spikes in blood glucose and lipids induce proportional increases in oxidative stress, which acutely trigger impairment endothelial, inflammation and increased risk of future cardiovascular events. In this research, we have investigated acute effects of vinegar intake on some of the biochemical atherosclerosis risk factors in high cholesterol fed rabbits to see if we can find a probable protective value for it. METHODS: The rabbits were randomly divided into four groups: normal diet, high cholesterol diet (%1 cholesterol), %1 cholesterol with 5 ml vinegar (low dose), %1 cholesterol with 10 ml vinegar (high dose). After fasting for 12-15 hours, blood samples were taken to determine baseline values. Three hours after feeding, blood samples were collected again to investigate acute effects of vinegar intake on the measured factors. RESULTS: Using high-dose vinegar with cholesterolemic diet caused significant reduce in LDL-cholesterol (LDL-C), oxidized-LDL (ox-LDL), malondialdehyde (MDA), total cholesterol (TC) and apolipoprotein B (ApoB) in comparison with hypercholesterolemic diet. Consumption low-dose vinegar with cholesterolemic diet induced a significant decrease in fibrinogen and glucose compared to hypercholesterolemic diet. Level of serum nitrite, nitrate, triacylglycerol (TAG), HDL-cholesterol (HDL-C), apolipoprotein A (ApoA), serum glutamic pyruvic transaminase (SGPT), serum glutamic oxaloacetate transaminase (SGOT) and C-reactive protein (CRP) were not significantly difference in low and high doses vinegar with cholesterolemic diet compared to hypercholesterolemic diet. A significant difference was observed for LDL-C, ApoB100 and TC between low and high doses vinegar. CONCLUSION: This study suggest that vinegar, might have some acute effects on biochemical risk factors of atherosclerosis and a probable protective value can be considered for its postprandial use.

Effects of apple juice on risk factors of lipid profile, inflammation and coagulation, endothelial markers and atherosclerotic lesions in high cholesterolemic rabbits.

BACKGROUND: Atherosclerosis which results from gradual deposition of lipids in medium and large arteries is a leading cause of mortality worldwide. The objective of this study was to determine the effect of apple juice on some risk factors of atherosclerosis and on the development of atherosclerosis in rabbits fed a high-cholesterol diet. METHODS: Thirty two male rabbits were randomly divided into four groups: normal diet, high cholesterol diet (%1 cholesterol), 1% cholesterol supplemented with 5 ml apple juice (low dose) and 1% cholesterol supplemented with 10 ml apple juice (high dose) for 2 month. The C-reactive protein (CRP), nitrite, nitrate, fibrinogen, total cholesterol(TC) and factor VII were measured before the experiment and by the end of period. At the end of study, fatty streak formation in right and left coronary arteries were determined using Chekanov method in all groups. RESULTS: Both doses of apple juice significantly were decreased TC, TG, CRP, fibrinogen, factor VII levels, atherosclerotic lesion in right and left coronary arteries and increased nitrite and nitrate compared to cholesterolemic diet. Also using 10 ml apple juice caused significant reduce in LDL-C and increase HDL-C, but 5 ml apple juice did not change these factors. Significant differences were observed between 5 and 10 ml apple juice groups by LDL-C. No significant difference was found between 5 and 10 ml apple juice groups with regard to CRP, nitrite, nitrate, fibrinogen, factor VII, TG, HDL-C and TC concentrations. CONCLUSION: Apple juice can effectively prevent the progress of atherosclerosis. This is likely due to antioxidant and anti-inflammatory effect of apple juice.

The role of hippocampal nitric oxide (NO) on learning and immediate, short- and long-term memory retrieval in inhibitory avoidance task in male adult rats.

There is impressive amount of evidence suggesting the involvement of nitric oxide (NO) in hippocampal synaptic plasticity and consequently learning and memory. Hippocampus is a brain region which is widely implicated in several types of learning and memory formation, including inhibitory avoidance learning. Since the CA1 region of hippocampus has shown nitric oxide synthase (NOS) activity, inhibition of the NOS enzymes can modulate hippocampal function, hence affecting memory processes. Therefore, we conducted series of experiments to further investigate the role of NO on inhibitory avoidance short- and long-term memory in rats. For this purpose, male Wistar rats were divided into 15 groups (n=10), and bilaterally implanted with guide cannulae aimed at the CA1 region of hippocampus. Animals received pre-training, post-training and pre-retrieval injections of vehicle (saline) or different doses of L-NAME (5, 10 and 15 microg/0.5 microl/side) or l-arginine (alone or in combination with L-NAME), tested for immediate, short- and long-term memory retention in an inhibitory avoidance task. Our results indicated that step-through latency (STL) of short- and long-term memory retention test was significantly reduced in L-NAME treated rats (15 microg/0.5 microl for immediate and short-term memory; 10 microg/0.5 microl for long-term memory), as compared to that of control group. Results also revealed that, L-arginine produced no any significant effect on STL, however could reverse the effect of L-NAME on memory. Our results also showed that, blocking of NO signaling immediately after training had no effect on either short- or long-term memory, indicating that NO release only during training, and not during consolidation, plays a role in memory formation. Together, our findings suggest that NO synthase inhibition by L-NAME can induce impairments in immediate, short- and long-term memories of inhibitory avoidance task, and these impairments are dependent on the learning and memory processes at which NOS inhibited.

Intra hippocampal injection of testosterone impaired acquisition, consolidation and retrieval of inhibitory avoidance learning and memory in adult male rats.

The hippocampus is essentially involved in learning and memory, and is known to be a target for androgen actions. Androgen receptors are densely expressed in CA1 of rat hippocampus, and mediate the effects of testosterone (T) on learning and memory. T depletion or administration can modulate neural function and cognitive performance. We conducted series of experiments to further investigate the effect of castration or intra hippocampal injection of T on acquisition, consolidation and retrieval of inhibitory avoidance learning and memory. Male adult rats were bilaterally cannulated into CA1 of hippocampus, and then received T (1, 10, 20, 40 and 80mug/0.5mul/side) or vehicle (DMSO), 30min before training, immediately after training and 30min before retrieval in inhibitory avoidance task. Castration was made by gonadectomy of male rats and behavioral tests performed 4 weeks later. Our results showed that gonadectomy of male rats did not influence performance on inhibitory avoidance task, as compared to sham-operated rats. We have also found that pre-training, post-training and pre-retrieval intra CA1 injections of T significantly decreased step-through latencies in inhibitory avoidance learning at doses 1 and 80, 20, and 20 and 40mug/0.5mul/side, respectively. The data suggest that intra CA1 administration of T could impair learning and memory acquisition, consolidation and retrieval, while systemic androgen's depletion have no effect on memory, in inhibitory avoidance task.

The effects of Vitex agnus castus extract and its interaction with dopaminergic system on LH and testosterone in male mice.

The purpose of this study was to evaluate the probable effects of Vitex agnus castus (Vac.) on the male reproductive physiology. It is a well known fact that LH secretion from the anterior pituitary of mammals is controlled by many neurotransmiters such as dopamine. In this experiment, we have studied the effect of Vac. extract on the LH and testosterone hormones and its interaction with the dopaminergic system on male mice. In order to evaluate these effects, we used the hydroalcoholic Vac. extract (for extraction we used percolation technique) injection with the following doses: 65, 165, 265, 365 and 465 mg kg-', bromocriptine as a dopamine receptor agonist (5, 10, 20 mg kg(-1)) and haloperidol as a dopamine receptor antagonist (1, 1.5, 2, 2.5, 3 mg kg(-1)). To study the interaction between Vac. extract and dopaminergic system, we injected the optimum doses of Vac. with bromocriptine or haloperidol at the same time. Intraperitoneal injections were applied in all experiments, once a day for 30 days. The control group remained intact and the sham group received vehicle. After the last injection, we collected the animal blood serums for hormonal assays. LH and testosterone were measured by Radio Immuno Assay (RIA). LH and testosterone, showed significant decrease in bromocriptine group and haloperidol increased these hormones. Vac. extract decreased significantly the LH and testosterone levels. The coadministration of Vac. extract and bromocriptine decreased LH and testosterone. Coadministration of Vac. extract and haloperidol decreased LH and testosterone levels. These results suggest: dopamine regulates the gonadotroph-leydig cells axis. It appears that Vac. exertes effects through dopaminergic system and other pathways. The findings of this study show we can use Vac. extract for pathological cases of increasing LH and testosterone.

Involvement of dopamine D2 receptors of the central amygdala on the acquisition and expression of morphine-induced place preference in rat.

In the present study, the effects of intra-central amygdala (CeA) injections of dopamine (DA) D2-like receptor agonist and antagonist on the acquisition and expression of morphine-induced place preference in male Wistar rats have been investigated. Subcutaneous administration of different doses of morphine sulphate (0.5-10 mg/kg) produced a dose-dependent conditioned place preference (CPP). Using a 3-day schedule of conditioning, it was found that the DA D2/D3 receptor agonist, quinpirole (0.3-3 microg/rat), or the DA D2 receptor antagonist, sulpiride (0.04-5 microg/rat), did not produce a significant place preference or place aversion. Intra-CeA administration of quinpirole (0.3 and 1 microg/rat) with an ineffective dose of morphine (0.5 mg/kg) elicited a significant CPP. On the other hand, quinpirole (0.3 microg/rat) injection into the CeA induced CPP in combination with the lower doses of morphine (0.5 and 2.5 mg/kg), but decreased the response of higher dose (7.5 mg/kg) of morphine. This response of quinpirole was attenuated by sulpiride (0.2 microg/rat). Sulpiride by itself (0.04-5 microg/rat) reduced the acquisition of morphine (7.5 mg/kg)-induced place preference. The administration of the higher dose of sulpiride (1 and 5 microg/rat) or the higher dose of quinpirole (3 microg/rat) during acquisition decreased the locomotor activity of the animals on the testing days. The injection of the low dose of quinpirole (0.3 microg/rat) on the test day reduced the expression of morphine-induced CPP, but the high dose of quinpirole (3 microg/rat) potentiated this expression. The administration of sulpiride (5 microg/rat) attenuated the quinpirole response. The injection of sulpiride (1 and 5 microg/rat) abolished the expression of morphine-induced CPP. It is concluded that the CeA DA D2-like receptors may play an active role in morphine reward.