Tail pinch

Tests for modulation of nociception (also hot plate, Randall Selitto, tail pinch) Body temperature... 

Similar to naloxone, majonoside-R2 also reduces stress-induced analgesia measured by the tail-pinch test (Nguyen et al. 1995). 

Stressful stimuli of many types produce marked increases in brain noradrenergic function. Stress produces regional selective increases in NE turnover in the locus coeruleus (LC), limbic regions (hypothalamus, hippocampus, and amygdala), and cerebral cortex. These changes can be elicited with immobilization stress, foot-shock stress, tail-pinch stress, and conditioned fear. Exposure to stressors from which the animal cannot escape results in behavioral deficits termed learned helplessness. The learned helplessness state is associated with depletion of NE, probably reflecting the point where synthesis cannot keep up with demand. These studies have been reviewed elsewhere in detail (Bremner et al. 1996a,b). 

Compound Tail pinch (mg/kg) PC02 (mg/kg) Safety ratio PC02 tail pinch... 

FIGURE 2 One-way cross-tolerance between DPI-3290 and morphine. Top panel illustrates data from rats receiving DPI-3290 (0.5 mg/kg, IM) subchronically (5 days) and subsequently challenged with DPI-3290 or morphine at day 6 (N = 6). Data illustrated in the bottom panel was obtained from rats that received morphine (5 mg/ kg, IM) subchronically (5 days) and were challenged with morphine or DPI-3290 at day 6. Antinociceptive responses were assessed by tail pinch test with an artery clamp. Pain responsiveness was assessed at both 20 and 30 min after drug administration. 

Clark JM, Clark AJM, Winn P (1992) N-methyl-D-aspartate lesions of the lateral hypothalamus do not reduce amphetamine or fenfluramine anorexia but enhance the acquisition of eating in response to tail pinch in the rat. Psychopharmacology 109 331-337... 

High doses of OPs cause similar toxic effects independent of the identity of the OPs. However, low-dose effects are not identieal for all OPs (Moser, 1995). For example, a low dose of fenthion decreased motor aetivity in rats by 86% but did not alter the tail-pinch response, whereas a low dose of parathion did not affect motor activity but did decrease the... 

A recent study of Moser eoworkers (2005) Mo,ser et uL (2005), using a do.se-additive design with mixtures of five commonly used OP pesticides (chlorpyrifos, diazinon, dimeihoate, acephaic, and malathion), showed a more-than-additive interaction on multiple end points blood and brain cholinesterase inhibition, motor activity, and gait score (tail-pinch response did not. show a more-than-additive interaction). This study is noteworthy because (i) relatively sensitive end points were used to test the toxic interaction of the OP pesticides, such as cholinesterase inhibition or depression of motor activity (ii) more than two OP compounds were used in the mixture and (iii) comprehensive statistical analyses of the data were performed. The pharmacokinetic interaction of two of the aimpounds in the mixture, chlorpyrifos and diazinon, has been studied in rats (Timchalk et a ., 2004). The authors found that one compound did not affect the pharmacokinetics of the other unless high doses were given, concluding that a more-than-additive interaction is unlikely at environmentally relevant concentrations. 

The antinociceptive effects of N. sativa (black cumin, Ranunculaceae) oil and its major component thymoquinone were investigated by Abdel-Fattah et al. (2000). After oral administration of doses ranging from 50 to 400 mg/kg the nociceptive response was suppressed in the hot-plate test, tail-pinch test, acetic acid-induced writhing test, and in the early phase of formalin test. There was also an inhibition of nociceptive response in the late phase of the formalin test after systemic administration and i.p. injection of thymoquinone. The s.c. injection of naloxone (1 mg/kg) significantly blocked the antinociceptive effect of N. sativa oil and thymoquinone in the early phase of the formalin test. In N. sativa oil- and thymoquinone-tolerant mice the antinociceptive effect of morphine was significantly reduced, but not vice versa. These findings indicate that N. sativa oil as weU as thymoquinone induce an antinociceptive effect by means of an indirect activation of pi- and p-opioid receptor subtypes. 

Boutelle, M. G., Svensson, L., and Fillenz, M., 1989, Rapid changes in striatal ascorbate in response to tail-pinch monitored by constant potential voltammetry. Neuroscience 30 11-17. 

Touch response, startle response, righting/palbebral/grasping reflexes, tail pinch, thermal nociception, ataxia, body temperature, pupil response. 

Tail pinch The response to the pressure applied to the tail. A normal animal will respond by vocalization or attempting to escape. A decreased or absent response indicates analgesia... 

Tail-pinch response No reaction Normal Slow reaction Energetic reaction Exaggerated reaction ... 

DilAienylpropylamines emd Miscellaneous thiophthalanes studied for analgesic activity,-most active. It was approximately equal to morphine (mice, hot-plate, tail-pinch and Mlsen tests), produced a Straub-tail reaction and was antagonized by nalorphine. Similar thiophthalanes with a propylamlno side chain had been previously studied as antidepressants, but were not analgesics and did not produce a Straub-tall. 

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