Physiology and Pharmacology
Year:2010 | Volume:13 | Issue:4|Papers Count:13

Introduction: Learning and memory processes result from interaction of neurotransmitter systems in various brain regions such as amygdala and hippocampus. Considering that morphine induces memory impairment, in the current study, we examined the possible role of cholinergic muscarinic receptors of the central amygdala (CeA) on the morphine-induced amnesia in adult male Wistar rats.Methods: A week after the surgery during which cannulas were bilaterally implanted in the CeA nuclei of the amygdale, the animals were trained and tested in a step-through type passive avoidance task with 24 h interval time. Memory retrieval was measured by step-through latency, which is the latency to enter into the black shocked compartment.Results: Post-training subcutaneous (s.c.) administration of morphine (5 and 7.5 mg/kg) dose-dependently decreased the step-through latency, suggesting morphine-induced amnesia. Post-training intra-CeA microinjection of pilocarpine (1 and 1.5mg/rat), muscarinic receptor agonist, significantly decreased the amnesia induced by post-training administration of morphine (7.5 mg/kg s.c.). Moreover, post-training co-administration of a muscarinic receptor antagonist, scopolamine (0.5 and 0.6mg/rat, intra-CeA) with an ineffective dose of morphine (2.5 mg/kg) inhibited memory retrieval. Post-training administration of the lower doses of scopolamine also reversed the influence of pilocarpine on the morphine response. It is important to note that post-training intra-CeA administration of the same doses of pilocarpine or scopolamine by itself had no effect on memory retrieval.Conclusion: The present results suggest that cholinergic muscarinic receptors of the central amygdala nuclei may play an important role in morphine-induced amnesia.

Introduction: Ascorbic acid (AA) is present in high concentrations with heterogeneous distribution in the mammalian brain. Previous studies have shown that release of various neurotransmitters such as glutamate, acetylcholine and dopamine might be involved in the central AA release. On the other hand all of these neurotransmitters and the region CA1 of the hippocampus are involved in learning and memory. The aim of the present study was to evaluate the effects of ascorbic acid injection in the CA1 region on spatial learning and memory in adult male rats.Methods: 42 adult male NMRI rats (250-300 g) divided into 6 groups were used in this study. They included control group that received no injection, sham-operated group that received normal saline injection as vehicle and four groups that received different doses of ascorbic acid (6, 12, 24 and 48 mg/rat). All injections were given in 5 consecutive days and 30 min after each injection, the rats were tested in the Morris Water Maze test to measure learning and memory task. Spatial learning and memory parameters were subjected to analysis of variance (ANOVA).Results: The results indicated that intrahippocampal microinjection of AA (12 and 24 mg/rat) significantly increased some spatial learning and memory parameters such as escape latency and path length to reach the hidden platform. Conclusion: Our findings show that AA injection into the CA1 region has a negative effect on spatial learning and memory.

Introduction: Angiotensin converting enzyme (ACE) is an exopeptidase that converts Angiotensin I to Angiotensin II. Angiotensin II is a potent vasoconstrictor and releases aldosterone, and have a critical role in hypertension. In this study, ACE insertion / deletion (I/D) polymorphism and ACE activity was determined in patients with coronary artery disease (CAD) and normal subjects. The correlation of these parameters with important CAD risk factors were also evaluated.Methods: 204 subjects were assigned to patients and normal groups based on their angiography results. Serum ACE activities were assayed by HPLC and I/D polymorphism were analyzed by PCR method. Important risk factors such as diabetes mellitus, hypertension, lipid profiles, ejection fraction, smoking and opium consumption were also recorded. Results: CAD was higher in DD genotype subjects (OR= 2.45; CI= 1.05-5.73), and ACE activity was about twice in DD compared to II genotypes. ACE activity was higher in hypertensives and diabetics in CAD group (p<0.001), but in the normal group it did not have any correlation with these risk factors. The rate of opium use was higher in ID and DD subjects.Conclusion: DD genotype is a risk factor for CAD and ACE activity is higher in this genotype. However, there is not any correlation between ACE activity and CAD.

Introduction: S100B is a protein released from astrocytes, which controls neuroglial relationship and probably plays a role in memory and synaptic plasticity. Study of the functional relationship between astrocytes and neurons is of great importance. The present study was conducted to evaluate the effect of S100B infusion into the CA1 region of the hippocampus, on memory performance in male rats. Methods: In this study, 40 male wistar rats were used. Animals were bilaterally implanted with indwelling cannulae in the CA1 region of the hippocampus. Seven days after surgery, animals were trained in a step-down passive avoidance task (0.5 mA, 100 Hz, 5 sec). Immediately after the training, animals received 0.5 ml infusion of saline or S100B (5, 50, 500, or 5000 ng) bilaterally. Twenty four hours later step-down first latency and total time spent on platform were measured as learning and memory indices. Results: The infusion of 5 ng S100B induced a significant increase in step-down first latency (p< 0.01), and also increased the total time spent on the platform compared to the control group (p < 0.001). Surprisingly, animals which received doses of 500 and 5000 ng showed a significant decrease in both indices compared to the control group (p< 0.001). Conclusion: Our findings indicate that astrocytic S100B protein has modulatory effects on memory, in a way that in nanogram doses facilitates, but in micrograms impairs memory in passive avoidance tas.

Introduction: Because of the relationship between olive oil consumption and low cardiovascular mortality and morbidity, we investigated the effects of dietary virgin olive oil (VOO) on serum lipids profile.Methods: Experimental mature male rats were treated with 0.25, 0.5 and 0.75 ml/kg/day of VOO for 30 days via gastric gavage, while the control group was treated the same way with saline (n=6). At the end of day 30, serum cholesterol, triglycerides, HDL cholesterol (HDL-c), LDL cholesterol (LDL-c) and VLDL cholesterol (VLDL-c) levels and atherogenic indices were determined in rats’ blood.Results: Analyses showed that the main unsaturated fatty acid in VOO is oleic acid. After VOO administration, cholesterol, triglyceride, HDL-c and VLDL-c levels were significantly increased compared to the control group (P < 0.05). LDL-c levels were decreased by all doses of virgin olive oil in a dose dependent manner and this reduction reached statistical significance in the 0.75 ml/Kg/day group vs. control. Olive oil significantly attenuated LDL-c /HDLc ratio in a dose dependent manner (in 0.25, 0.5, and 0.75 ml/kg/day groups was 4.27 ±0.64, 3.85 ± 0.72, and 1.78 ± 0.48, respectively compared to 8.55 ± 0.2 in control group). VOO decreased TG/HDL-c ratio in 0.5 and 0.75 ml/kg/day groups (13.21 ± 1.07 and 12.45 ± 0.41, respectively) vs. 16.51 ± 0.94 in control group. Conclusion: Results of this study showed that VOO can attenuate atherogenic indices possibly due to the high presence of oleic acid in this oil.

Introduction: In this study, two constituents of saffron stigma (crocin and safranal) were tested for possible cytotoxic and antitumoral activity using brine shrimp and potato disc assays.Methods: In the brine shrimp assay, three wells containing 10 nauplii were tested for each concentration. After 24h, the number of the nauplii was counted. To investigate the antimicrobial activity of safranal and crocin against Agrobactrium tumefaciens, the MIC of these compounds were evaluated using microplate and spectrophotometry method. In the potato disc assay, discs of potato were cut with specific diameter and transferred on 1.5 % agar under laminar air cabinet. Discs were incubated with 50 ml of a mixture containing suspension of Agrobactrium tumefaciens (108 cfu/ml) and 50ml of a solution of safranal (0.075, 0.150, 0.300, 0.450, 0.600 and 0.800 mg/ml ) or crocin (0.5, 1.0, 1.5, 3.0, 6.0 and 8.0 mg/ml) (1:1) in 25°C for 20 days until the tumors were counted. Results: The MIC of safranal and crocin were 1 and 10 mg/ml. The LC50 values of safranal and crocin against brine shrimp were 14.342 and 147.036 ppm. The percent of tumor growth inhibition of safranal at 0.075-0.800 mg/ml and crocin at 0.5-0.8 mg/ml were 5.6-90.2 % and 5.2-88.8 %, respectively and the EC50 Values of safranal and crocin against tumors were 0.31 and 2.34 mg/ml, respectively.Conclusion: Both safranal and Crocin have remarkable toxic effect and suitable dose dependent antitumoral activity. Between the two compounds, safranal has higher toxic effect and antitumoral activity compared to crocin.

Introduction: Barrel cortex of rodents is responsible for sensory information processing from muzzle whiskers. Locus coeruleus (LC) as the main source of norepinephrine (NE) in the cortex, is effective on the sensory information processing.Methods: Rats were divided to 2 groups. One group underwent sensory deprivation (P4) and the other group served as control and did not undergo sensory deprivation. Response properties of the neurons were evaluated by extracellular single unit recordings following a controlled mechanical deflection of the principal whisker (spared whisker), or before the simultaneous deflection of principal and adjacent whiskers (trimmed whisker) were assessed. In the P4 group, all whiskers on the left muzzle, except D2, were trimmed every other day for two months. In both groups, LC was electrically stimulated 0, 50, 100, 200, 400 and 800 ms before controlled principal whisker deflection. Response magnitude, latency and CTR index (lateral inhibition index) were assessed.Results: In the P4 group, deflection of the principal whisker without LC electrical stimulation, increased the response magnitude and CTR index, but decreased the response latency compared to the control group. The magnitude of the response of neurons to the principal whisker deflection was significantly different between P4 and control groups, in following of principal whisker deflection in times of LC stimulation showed significant difference only in 50 ms subgroup. In both groups, pro-stimulation differences in CTR index and response latency remained unchanged after LC stimulation.Conclusion: Our data showed that electrical stimulation of LC following sensory deprivation modulates neuronal response properties and changes their response pattern.

Introduction: Recent increase of endocrine disorders may be correlated to the increased exposure to electromagnetic fields from various instruments. Radiation leakage from microwave oven may be harmful for users. Ladies have the highest levels of contact with microwave ovens. This study was carried out to evaluate the effect of radiation leakage from microwave oven on body weight, cortisol and thyroid hormones.Methods: Radiation leakage of microwave oven was measured by RF measuring instrument. For this study, 20 adult two-month-old female mice weighing 25-28 g were randomly divided in control and test groups. Test group was exposed to 2450 MHZ microwaves produced by a microwave oven 3 times a day, 30 minutes each time. After 60 days, body weights of both groups were determined and blood was collected by heart puncture. Cortisol and thyroid levels were evaluated in serum by an RIA method.Results: radiation leakage from oven showed variation and ranged from 6.5 to 57.5 mW/cm2. Mean body weight changes in test and control groups were 0 and 4.54 grams, respectively. Cortisol (23.6±2.24 vs. 13.6 ±1.47 ng/ml) and T4 (98.4 ± 7.3 vs. 67.0 ± 5.9 nmol/L) levels were significantly increased in the test group compared to the control group, respectively. Level of T3 did not alter significantly.Conclusion: We found that microwaves leaked from oven decrease body weight and increase T4 and cortisol levels, and therefore have deleterious health effects.

Introduction: Atherothrombotic diseases such as myocardial or cerebral infarction are serious consequences of the thrombus formation in blood vessels. Thrombolytic agents are used to dissolve the already formed clots in the blood vessels. However, these drugs have certain adverse effects, which cause serious and sometimes fatal consequences. Methods: Plants essential oils were prepared and analyzed by GC/MS. To evaluate the fibrinolytic effect, fibrinogen labeled with FITC was added to the plasma. Ca2+ was used for production of labeled clot. The essential oil (1/10, 1/100, 1/1000 dilutions) with and without streptokinase as a positive control, were added. Fluorescence was determined after 10, 20, 40 and 60 minutes (excitation = 478, emission = 510). Results: Our findings showed that carvacrol was the main component of Zataria multiflora essential oil. This essential oil showed the best fibrinolytic activity. Curcuma domestica also showed fibrinolytic activity, which might be related to the presence of curcumene, zingiberene and tumeron. The main component of Cinnamomum verum essential oil was cinnamaldehyde and fibrinolytic activity of this essential oil was lower than Zataria multiflora and Curcuma domestica.. The essential oil from Heracleum persicum with main components such as hexyl butyrate and liner esters did not have any significant fibrinolytic activity. Conclusion: In our study, it was found that Zataria multiflora, Curcuma domestica and Cinnamomum verum can dissolve blood clots in vitro. However, in vivo clot dissolving properties of these plants are yet to be discovere.