[Effect of short-term forced exercise on naloxone induced withdrawal symptoms in morphine addicted male rats]

Opioid dependence has been causing limitation in usage of morphine and other opioid drugs in pain control. The aim of this study was to assess the effect of short-term forced exercise on withdrawal syndrome in morphine addicted male rats. This experimental study was done in the physiology research center of Ahwas Jondishapour University of Medical Sciences. Twenty four young male Wistar rats, weighing 200-300gr, were randomly divided into four groups: no addiction and no exercise, no addiction and exercise, addiction and no exercise and addiction and exercise. The exercise groups underwent treadmill forced exercise for ten days. The first five days morphine was administrated [ip] twice daily with increasing dose [5, 10, 20, 40, 50 mg/kg] to addicted groups. Also single dose [50mg/kg] of morphine was administrated to them on the 10[th] day of exercise. After administration of naloxone hydrochloride the withdrawal symptoms were evaluated for 5 minutes. The findings of this study were analyzed by SPSS software and One- way ANOVA [Tukey] test. The findings of this study showed that the withdrawal symptoms was elevated in exercise and addicted groups in comparison with control group [p<0.05, p<0.01]. However, most of withdrawal symptoms decreased in addicted and exercise group in comparison with addicted and no exercise group [p<0.01, p<0.001]. The exercise could increase endogenous opioid and withdrawal symptoms in animals but reduce withdrawal symptoms in addicted and exercise groups compared to addicted and no exercise group. Its mechanism might be related to down regulation and low sensitivity of opioid receptors

[Introduce a model for diffuse brain injury in rats]

Diffuse brain injury occurs in nearly half of all severe of clinical traumatic brain injuries and has been associated with high mortality. Brain edema is a mortal pathological condition, which is commonly observed in diffuse brain trauma. In the current study, a new model producing diffuse brain injury, without focal brain lesions, was developed in rats, for first time in Iran. Diffuse brain trauma was produced in 45 male rats that they were divided into three groups; control, sham, and trauma group. Rats in two later groups underwent general anesthesia using a mixture of halothane, oxygen and nitrous oxide. A stainless steel disc [1cm in diameter] was firmly fixed to central portion of skull vault using dental acrylic. In the trauma group, a weight of 450g was allowed to drop from the 2m height onto the disc when trauma device was ready. All animal were mechanically ventilated during the treatment. In all groups, pathological studies and measurement of brain edema were performed at 24 hours following injury. Brain edema was evaluated by water content of brain and extravasation of Evans blue [E.B] dye. The results of present study indicated that this technique induces a diffuse brain injury in the rats, as it was shown by a siginificant increase of brain water content in the trauma group compared to the control and the sham groups [p<0.05]. In addition, the extravasation of E.B content was significantly more in the trauma group than other two groups [p<0.001]. Pathological examinations showed diffuse brain ischemia and brain edema as well. Taken overall, this technique is introduced as a successful and suitable model for studying neuronal and vascular changes associated with diffuse brain injuries

Spasmolytic effect of Cuscuta pentagona fruit aqueous extract on rat ileum

Cuscuta pentagona [convolvulaceae] has been used in Iran for gastrointestinal disorders. The aim of the present study was to investigate the effect of Cuscuta pentagona fruit aqueous extract [CPE] on rat ileum contractility. The fruit extract was prepared according to the traditional method by boiling the fruits in distilled water. Ileum was dissected from adult male Wistar rat, mounted in an organ bath [10 ml] containing Tyrode solution [37°C, pH 7.4]. I leal contractions were recorded under 1 g initial tension, by an isotonic transducer. In many in-vitro studies, potassium chloride and acetyl cholin induced contractions of rat ileum in the absence or presence of some antagonists had been assessed. In some in vivo studies gastrointestinal transit time in different groups of rats after administration of saline, three doses of fruit extract or atropine, had been measured. Cumulative concentrations of CPE [0.5-8 mg/ml] reduced the ileal contractions induced by KC1 [60 mM] and ACh [1 microM] revealing a dose dependent effect [p<0.0001]. The spasmolytic effect of CPFAE was not reduced after 20-30 minutes of tissue incubation with phentolamine [ImicroM], propranolol [lmicroM] L-NAME 100 microM] and naloxone [1 microM]. In.a Ca[2+]-free Tyrode solution the ileum depolarized by KC1, 120 mM was contracted by addition of cumulative concentration of CaCl[2] [0.225 to 3.6 mM] but CPE [2 and 4 mg/ml] reduced the contractions in a dose dependent manner [p<0.0001]. Furthermore, fruit extract in concentrations of 250, 500 and 750 mg/kg [p.o.] reduced the transit time of charcoal meal in small intestine in a dose dependent manner. Our results suggest that the CPE spasmolytic effect is mediated via calcium channels without involvement of adrenoceptors [alpha and beta] or opioid receptors or any influence on NO synthesis. The results of the present study showed that Cuscuta pentagona fruit aqueous extract reduces rat ileum motility in both in vivo and in vitro studies

[Effects of intramedial septum infusion of physostigmine on hippocamal EEG and spatial memory in animal model of Alzheimer's disease]

The basalis magnocellularis nucleus [NBM] cholinergic projections to amygdala and forntal cortex have a crucial role in spatial learning and memory. There are relations between septum, hippocampus, amygdala and cerebral cortex. The role of NBM cholinergic projections to medial septum and then to hippocampus on spatial learning and memory, hippocamal EEG in animal model of Alzheimer's disease was assessed after unilateral lesion of NBM with phtalic acid [300 ng/kg]. Physostigmine was infused into the medial septum. Forty wistar male rats were divided in 4 groups: control, lesioned, lesioned received saline and lesioned treated with physostigmine [5microg/microl]. Animals were operated stereotaxicaly for NBM lesioning, intramedial septum cannulation and hippocamal electrode implantation. Rats were trained one session daily into T-maze and alterations of hippocampal EEG amplitude were evaluated. The results showed intramedial septum infusion of physostigmine improves spatial learning and memory in lesioned animals significantly [p<0.01]. NBM cholinergic projections to medial septum and then the hippocampus as well as its projections to amygdala and cortex have a role in spatial learning and memory. Administration of physostigmine improves decrease of hippocampal EEG amplitiude, spatial learning and memory impairment that was induced by NMB lesioning in male rats