32 24765236 Iranian Society of Physiology and Pharmacology 330 Hippocampal kindling facilitates amygdala-kindled seizures in rats Mirnajafizadeh Pourgholami Fathollahi Behzadi 1 11 1998 2 2 95 103 12 08 2007 15 05 2014   In this study, the effect of an experimentally increased excitability in hippocampal neurons, via hippocampal kindling, on amygdala kindling rate was investigated in rats. Animals were divided into 4 groups. In all groups, except group 2, tripolar electrodes were implanted in the amygdala and CAI region of the dorsal hippocampus. Group 2 animals were only implanted with tripolar electrodes in the amygdala. In group 1, the rats were kindled one week after surgery, first from the hippocampus, then by amygdala stimulation the next day. In groups 2 and 3, rats were kindled one week after surgery from the amygdala. Group 4 animals had a recovery period of one week plus 32 days, which was the mean of the hippocampal kindling rate in group 1, and then they were kindled from the amygdala. In group 1, the amygdala kindling rate (n number of stimulation trials that must be administered before the stage 5 motor convulsion is triggered) was significantly facilitated and seizure at day n/2 during amygdala kindling was significantly increased. There was also a significant positive correlation between hippocampal and amygdala kindling rates. Results obtained in the present study show that an increase in hippocampal excitability in group 1 could facilitate kindling from the amygdala. Thus it may be suggested that the hippocampus has an important role in the development and propagation of seizures from the amygdala.   
331 Alterations in the vascular β-adrenoceptors of the rabbit knee joint due to acute inflammation 1 11 1998 2 2 104 112 12 08 2007 15 05 2014   It has been shown that acute inflammation reduces the effectiveness of sympathetic nerves in the regulation of knee joint blood flow. To investigate the role of vascular β- adrenoceptors in this event, 12 NZW rabbits were maintained anaesthetized by 1 % halothane in N2O/O2, and acute knee joint inflammation was induced by intra-articular injection of 1 ml of 2% carageenan solution 24 hours before the experiment. On the day of the experiment, a cannula was surgically inserted into the carotid artery to record blood pressure. The medial head of the biceps femoris muscle was removed to provide access to the posterior capsule of the knee and blood flow was measured using a laser flowmeter. Drugs were administered to the joint through a cannula in a branch of the tibial artery. The posterior articular nerve of the knee was also exposed so that it could be electrically stimulated. Electrical stimulation of the posterior articular nerve resulted in a 14.1 ± 3.2% reduction in blood flow measured by laser Doppler flowmetry. This response was reversed to vasodilatation by phentolamine (6.7 ± 1.8%), suggesting the presence of both α and β-adrenoceptors. The vasodilatation response was blocked by propanolol (α β-antagonist) and reduced to about 50% by atenolol (α β1 -antagonist). Also, close intra-arterial injection of different doses of β-agonists increased the joint blood flow by a potency rank order of isoprenaline (β)>dobutamine (β1)>salbutamol (β2). These effects were reduced or blocked by β-antagonists with a potency rank order of propanolol>atenolol. Overall, this study showed a balance between β-adrenoceptor subtypes in the inflamed joint. Compared to our previous investigation on the normal rabbit knee joint in which β1-adrenoceptors were shown to be predominant, acute inflammation caused a shift of β1 towards β2 in the adrenoceptor profile. The clinical significance of this change is not clear at the present time. 332 Salami Zavareh Mahmood Fathollahi Yaghub Esteky Hossein Motamedi Fereshteh Atapour Nafiseh 1 11 1998 2 2 113 120 12 08 2007 15 05 2014 333 Effects of low concentrations of lead on memory and learning in rats 1 11 1998 2 2 121 127 12 08 2007 15 05 2014   Lead poisoning is the most significant preventable disease of environmental origin. Neurodevelopment is highly complex and there are numerous opportunities for lead to interfere with normal development. Lead acetate can disrupt the action of the CNS and the development of dendrites and axons. The present study was carried out to assess the effect of low-level lead exposure on memory and learning. Three groups of Wistar rats (190-220 g) were exposed to low concentrations of lead during different phases of development for a period of 21 days. Exposure was initiated at conception (group I), at parturition (group II), or after weaning (group III). The drinking water of the experimental groups was replaced by 0.05%, 0.1% or 0.2% lead acetate solution. Each test group had a control, which received double distilled water. In this behavioral study, active avoidance conditioning was used. The learning acquisition test showed decreased shocks in lead exposed as compared to control male rats in groups II and III (0.05%, 0.2%). Memory testing also showed a reduction in the number of shocks in groups II and III (0.05%, 0.2%) compared to the controls. In contrast, male rats in group I which were exposed to 0.1% lead acetate showed an increase in the number of shocks. These results were similar to GABA, which produced a depressant effect on the CNS and decreased attention in animals. Although the mechanisms of lead poisoning in the CNS are not clear, various studies suggest that lead acetate probably increases the spontaneous release of neurotransmitters in the synapse and blocks impulse conduction. 334 The effect of CCK receptor agonists and antagonists in sciatic nerve-ligated mice 1 11 1998 2 2 128 136 12 08 2007 15 05 2014 The effects of caerulin, a CCK receptor agonist, and proglumide, a receptor antagonist, on hyperalgesia induced by sciatic nerve ligation, was studied in mice. Tolerance to the morphine response was obtained 3,7, 14,21 and 28 days after unilateral sciatic nerve ligation. Maximum hyperalgesia was found 14 days after nerve ligation. Caerulin increased morphine antinociception in nerve-ligated animals. The drug also induced antinociception in intact animals. Proglumide also induced antinociception in nerve-ligated mice. The antagonist increased the morphine response but did not alter the effect of caerulin. We conclude that the CCK receptor mechanism may have a role in hyperalgesia induced by nerve ligation 335 The role of nitric oxide in conditioned place preference induced by morphine in male mice Sahrai Hedayat Shariati Mohammad Reza Aghai-Firoozabadi Hasan Khoshbaten Ali Asgari Alireza Ghoshooni, Hasan 1 11 1998 2 2 137 143 12 08 2007 15 05 2014   The involvement of nitric oxide (NO) in the reinforcing properties of opioids was studied by examining the effect of a NO precursor (L-arginine) and NO synthase inhibitor (L-nitro-amino-methyl-ester, L-NAME) on the conditioned place preference (CPP) induced by morphine. The experiment was performed on male albino Swiss- White mice (25 ± 5 g). L-arginine in doses of 100, 200 and 500 mg/kg (i.p.) decreased CPP significantly, while L-arginine induced CPP in doses of 200 and 500 mg/kg per se. L-NAME doses of 0.75, 1.25, 2.5, 5, 10, 20 and 300 mg/kg (i.p.)had no effect on CPP induced by morphine, but injection of L-NAME (5 mg/kg) significantly decreased the effect of L-arginine on morphine-induced CPP. Therefore it may be concluded that NO may be involved in the psychological dependence to morphine.   336 Effects of ketotifen on oxytocin-induced contraction in the isolated rat uterus 1 11 1998 2 2 144 149 12 08 2007 15 05 2014   Preterm labor is one of the major causes of neonatal mortality and morbidity. Despite significant improvement in care for premature neonates, the most suitable and inexpensive treatment is prevention of preterm labor by inhibiting uterine contractions. The aim of this research is to obtain scientific evidence for the relaxant effect of ketotifen on the rat uterus and to provide the preclinical information that may indicate the clinical usefulness of ketotifen in preterm labor. Our studies have shown that ketotifen is a potent uterine muscle relaxant for contractions induced by oxytocin. Compared to controls and samples exposed to diazoxide (a vasodilator) and terbutaline (a β2-adrenergic agonist), we conclude that ketotifen is more effective than diazoxide and similar to terbutaline. 337 Chemical ablation of the hypothalamic arcuate nucleus and its effect on electroencephalographic tracings and pain threshold in the tail flick test 1 11 1998 2 2 150 154 12 08 2007 15 05 2014   The present study was carried out to explore the possible involvement of the arcuate nucleus of the hypothalamus in the inhibitory descending pain control system associated with the tail flick test and EEG recordings. Adult male (NMRI) albino rats weighing 200 ± 20 g were used. Rats were divided into three groups: experimental, sham and control. The arcuate nucleus was destroyed unilaterally by kianic acid under general anesthesia in the experimental group. In the sham-operated group, a vehicle of kianic acid was administered unilaterally to the arcuate nucleus while the control group was left intact. EEG rhythms were recorded by implanting electrodes placed on the frontal and occipital areas of the skull. Following the recovery period, pain threshold was measured by the tail flick test along with and without EEG recording. The results following unilateral chemical lesions of the arcuate nucleus showed a decreased pain threshold when compared to the sham and control groups. EEG recording and mean frequency showed no significant changes before and after noxious stimulation. Comparison of the EEG recordings before and after pain induction in the experimental, sham and control groups showed a significant reduction in alpha rhythm and also a significant increase in delta rhythm and mean frequency following noxious stimulation. Beta and theta rhythms showed no significant changes.   338 Comparison of the protein pattern of mouse parotid glands in pre- and post-administration of dobutamine and terbutaline 1 11 1998 2 2 155 161 12 08 2007 15 05 2014   To detect the effects of sympathomimetic drugs with selective action on β1 and β2 adrenoceptors, male albino mice were treated by intraperitoneal administration of dobutamine and terbutaline for 15 days. Three groups of mice were selected as dobutamine, terbutaline and control groups, respectively. At the end of the experiment, the animals were sacrificed and the parotid glands were removed and prepared for biochemical studies. The two drugs induced an increase in the weight of the parotid glands compared to the controls (p<0.01). On the other hand, the total protein and α-amylase levels of the glands increased significantly by the drugs (p<0.01). SDS-PAGE of the parotid glands revealed new protein bands in the dobutamine and terbutaline groups. The density of the protein bands with molecular weights of about 50 and 40 Kd in the experimental groups showed that the synthesis and storage of amylase increased in the parotid glands by long-term administration of the drugs. A 37 and 21 Kd increase in the density of the protein bands in the dobutamine and terbutaline groups shows that the synthesis of proline-rich proteins (PRPs) may have increased. Also, this research indicates that the number of β-adrenoceptors may be high in the mouse parotid gland.   339 The interaction of lead acetate and morphine in analgesia during the formalin test in mice 1 11 1998 2 2 162 169 12 08 2007 15 05 2014   In this study, the effects of lead acetate on two types of pain (nociception and inflammation) induced by formalin and its interaction with the opioid system and morphine-induced analgesia were examined. Male albino mice weighing 22-27 g were used in the experiments. Morphine was administered subcutaneously 30 minutes before formalin injection. Lead acetate was intraperitoneally administered 90 minutes before any injection. Different doses of morphine induce antinociception in both phases of the formalin test. Lead acetate induced no does-dependent nociception in the early phase, but caused dose-dependent analgesia in the late phase. Pretreatment with lead acetate antagonized the effect of morphine in the early phase. On the other hand, the effect of lead acetate in the early phase was reduced by morphine and its effect was eliminated in the late phase. We conclude that lead acetate can modulate the pain response and interact with morphine-induced antinociception. Additional research is suggested to identify the mechanisms of these effects.