The effects of the muscarinic antagonists, scopolamine HBr and MeBr, a cholinesterase inhibitor, E2020, and K+ channel blockers, 4-aminopyridine (4-AP) and apamin, on the performance of rats in a delayed matching to position (DMTP) task were examined. The percentage of correct choices (choice accuracy), number of trials completed and intertrial intervals were measured. Discriminability and response bias were also calculated, using signal detection analysis. Scopolamine HBr (0.1 mg/kg), but not scopolamine MeBr (0.1 mg/kg), significantly and consistently reduced the choice accuracy and discriminability, but neither affected the other measurements. E2020 (0.03-1.0 mg/kg) had no effect on the baseline performance in the DMTP task, but at 1.0 mg/kg, it significantly attenuated the deficits in choice accuracy induced by scopolamine. 4-AP (0.001-0.1 mg/kg) had no effect on either baseline performance or deficits induced by scopolamine. Apamin (0.1-0.4 mg/kg) had no effect on choice accuracy and discriminability. Apamin also failed to attenuate the scopolamine-induced deficits. When administered in combination with scopolamine, apamin at 0.4 mg/kg significantly decreased the number of trials completed and increased the intertrial interval relative to that of the control group. Taken together, these results demonstrate that K+ channel blockers (4-AP and apamin), unlike a cholinesterase inhibitor (E2020), fail to reverse the scopolamine-induced deficits in the DMTP task.

The earthquake that struck Bam, Iran, in December 2003 was one of the most catastrophic natural disasters in recent years. Medical and assistance activities conducted by Iranian military forces in this event are discussed in light of the special capabilities of the military forces in search and rescue missions. Among the most significant activities of the Iranian military forces in this event are the following: reporting the first news about the event, starting search and rescue missions in the first hour after the disaster by the 1st Brigade of Bam as the first assisting force, setting up two field hospitals as the first Iranian field hospitals in the disaster area, transporting 937 assistance, medical, and health care personnel to the disaster area in the first day, setting up 23 field emergency and 13 field assistance centers in the area, running 8 post-hospital care centers throughout the country, and playing a significant role in airlifting 11,792 casualties to different hospitals around the country. Based on the recent experience and the exclusive abilities of military forces, a special role for these forces in search and rescue missions should be considered.

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In the present study, the effects of intraperitoneal, intra-accumbal and intra-ventral tegmental area administration of L-arginine and N(G)-nitro-L-arginine methyl-ester (L-NAME) on conditioned place preference behavior were studied. Intraperitoneal (i.p.; 0.5, 1 and 5 mg/kg) and intra-accumbal (intra-NAc; 0.3, 1 and 3 microg/rat), but not intra-ventral tegmental area (intra-VTA; 0.3, 1 and 3 microg/rat) administrations of L-arginine produced a significant place conditioning. Similar injections of L-NAME did not produce any response. However, intraperitoneal pretreatment of the animals with L-NAME (5, 10 and 20 mg/kg), 30 min before L-arginine administration, significantly abolished the acquisition of place conditioning induced by either intraperitoneal or intra-accumbal injection of L-arginine. Moreover, injection of L-NAME (5, 10 and 20 mg/kg) on the test day did not alter the L-arginine response. The results may indicate that L-arginine induces conditioned place preference via an increase in nitric oxide (NO) in the nucleus accumbens.

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SUMMARYAttempts have been made to dissociate the cognitive effects of scopolamine from its noncognitive effects. It has been suggested that low doses of scopolamine may induce memory impairment without inducing significant non-cognitive effects. We therefore tested changes in locomotor activity (as a non-cognitive effect) in rats treated with low-dose scopolamine (which is believed to induce cognitive effects only).In this study, locomotor activity (as a non-cognitive effect) induced by low doses of this drug was evaluated by using two methods and rat strains. In the first study (circular box method, an automated open-field), scopolamine hydrobromide (HBr), scopolamine methylbromide (MeBr) or saline was injected subcutaneously into male Sprague-Dawley rats. After 30 min, rats were put into an automated open-field and locomotor activity was quantified by recording interruptions of infrared beams, with print-outs every 2 min for 16 min. Locomotor activity was assessed by summing these recordings. In the second study (closed platform), scopolamine HBr or saline was injected intraperitoneally into male Long-Evans rats. Twenty minutes later, the rats were placed in the center of a square-shaped closed platform (with 3x3 divisions). Locomotor activity was defined as the sum of crossings (traversing of four paws of the rat from one area into another of nine) and rears, which were recorded every 5 min for 20 min.Results from the circular box study showed that scopolamine HBr produced a marked increase in locomotor activity whereas scopolamine MeBr produced a non-significant decrease in locomotor activity. The closed platform data also demonstrated that scopolamine HBr increased locomotor activity significantly.These data show that scopolamine can induce non-cognitive effects (such as increased locomotor activity), even at low doses. Our results also imply that the increase in locomotor activity is mediated centrally.

Background: It is generally believed that the anticholinesterase effect is induced by the organophosphate insecticide parathion only through its bioactive metabolite (i.e., paraoxon) that is created in the liver. Objectives: This study aimed to evaluate the intrinsic anticholinesterase effect of parathion, compared to its main metabolite. Methods: This study has been conducted to prepare the isolated chick biventer cervicis nerve-muscle using the twitch tension recording method. Results: According to the results, paraoxon (0.1 µM) induced a highly significant increase (more than 100%) in the twitch height, while higher concentrations (0.3 and 1 µM) induced partial or total contractures. Furthermore, parathion induced almost the same percentage of increase in the twitch height at 1 µM and partial or total contractures at 3 and 10 µM. It should be noted that pralidoxime (2-PAM), at 300 µM, reversed the effects of paraoxon and its parent (i.e., parathion). Conclusion: These results demonstrate that both parathion and its metabolite inhibit the acetylcholinesterase enzyme which can be reactivated by pralidoxime, whereas parathion is about 10 times less potent, compared to its metabolite. Therefore, the intrinsic toxic effects of parathion, regardless of its metabolite, should be considered in future studies.

Introduction: Ethanol is a suitable solvent for many in vivo and ex vivo studies. However, it can interfere with normal muscle contraction and make variations in the results. Contrary to the present study, previous investigations revealed the suppressant effect of ethanol on muscle contraction. Methods: This study was based on an isolated chick biventer cervicis nerve-muscle using the twitch tension recording technique. Nerve and muscle complexes were exposed to several concentrations of ethanol (100, 200, 300, 400, and 500 mM), and impulses were recorded. Results: Twitch height increased in time and dose-dependent manner, and the concentration of 500 mM of ethanol after 30 minutes revealed the most elevation of muscle impulses. Conclusion: The potential effects of ethanol on striated muscle contraction are important and should be considered in studies using ethanol as a solvent.