Hot-plate test

Rats are placed onto a hot metal plate maintained at 52 °C surrounded by a Plexiglas cylinder (Height 26 cm Diameter 19 cm). The hot plate apparatus we use is provided by Apelex, 92220 Bagneux, France (Model DS37). The latency to the first foot-lick is measured (maximum 30 seconds). 

Ten rats are studied per group. The test is performed blind. 

The test substance is generally evaluated at 4 doses, administered p.o. 60 minutes before the test, and compared with a vehicle control group. 

Morphine (128 mg/kg p.o.), administered under the same experimental conditions, is used as reference substance. 

The basic experiment therefore includes 6 groups. EVALUATION 

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Pain Mouse hot-plate test Induces nociception [46]... 

The furan derivative (23) has been tested in vivo in tests of motor activity (open-field test) and antinociception (hot-plate test) as well as its capacity to enhance the hypokinetic and/or analgesic actions of subeffective doses of... 

The hot plate test with a 55 °C platform was used to measure latency to hindlimb lick at 12 or 18 minutes postinjection in rats. 

More rudimentary tests to identify the stability of powders are the so-called "hot plate" tests. Here, the substance is placed in a well-defined manner (circular, specified thickness of the layer, and so forth) on a hot plate with a controlled temperature. The temperature in the center of the layer is recorded continuously, and the progress of the self-heating is followed. Observations are made if self-heating of the substance occurs, the induction period of such self-heating, and the extent of the effect such as smoldering or spontaneous ignition. 

Both self-heating and self-ignition characteristics are commonly determined by adiabatic tests (self-heating) and hot-plate tests (self-ignition). These tests are limited in their applicability because they do not fully simulate the plant conditions. 

Materials salicylic acid, methanol, distilled water, 10-mL graduated cylinder, Beral pipette, 250-mL beaker, concentrated sulfuric acid, top or bottom of a petri dish, cotton ball, small test tube, balance, weighing paper, hot plate, test-tube holder... 

Interactions are seen between cocaine and the opioid system in analgesia. A synergistic effect occurs when cocaine is combined with a ju agonist (morphine) in the hot-plate test and a k agonist (U69,593) in the hot-plate test (Waddell and Holtzman 1999). Cocaine enhances morphine analgesia in several analgesic paradigms (e.g., formalin test, hot-plate test, and thermal tail-flick test)... 

Rylski M, Duriasz-Rowinska H, Rewerski W. (1979). The analgesic action of some flavonoids in the hot plate test. Acta Physiol Pol. 30(3) 385-8. 

XXXIIb) has a radically lower potency than the parent (hot plate test in mice A -Me derivative, inactive at 100 mg/kg fentanyl, EDso 0.01 mg/kg [118]). In this respect fentanyl is allied to acyclic basic anilides such as diampromid but it... 

So far, a role in mediating acute antinociceptive responses has been ascribed to different types of K+ channels using in vivo pain models such as the tail-flick or the hot-plate test. 

Hot plate Mouse Fentanyl BAY K 8644 (Agonist) BAY K 8644 increases reaction time in the hot plate test dose-dependently (1-10 mg/kg p.o.) Hoffmeister and Tettenborn (1986)... 

Del Pozo, E., Ruiz-Garcia, C., Baeyens, J.M. Analgesic effects of diltiazem and verapamil after central and peripheral administration in the hot-plate test, Gen. Pharmac. 1990, 21, 681-685. 

Malmberg, A.B. and Yaksh, T.L. Effect of continuous intrathecal infusion of co-conopeptides, N-type calcium-channel blockers, on behavior and antinociception in the formalin and hot-plate tests in rats, Pain 1995, 60, 83-90. 

The extraordinary antinociceptive potency of the unknown compound was determined in a mouse model of acute nociception, the hot plate test. Despite the Straub-tail effect observed earlier, the antinociceptive effect of the compound could not be not antagonized with the p-opioid receptor antagonist naloxone but with the nAChR antagonist mecamylamine, so the unknown compound was deduced to be a potent nicotinic analgesic (Spande et al., 1992 Qian et al., 1993 Badio and Daly, 1994 Sullivan and Bannon, 1996). 

Anandamide was shown to alleviate nociception in several behavioral animal models, e.g. the hot plate and formalin test (Calignano et al., 2001). A most interesting aspect of anandamide with respect to pain research is that it seems to bind to the hypothetical third cannabinoid receptor (Di Marzo et al., 2000b) In the hot plate test anandamide is still antinociceptive in CB/ mice, which is consistent with the observation that the selective CBi receptor antagonist SR 141716A does not block motor inhibitory and antinociceptive effects of anandamide in wild-type mice. 

A3AR ko have decreased nociception, as assessed by the hot-plate test (Fedorova et al. 2003), probably due to a decrease in the supraspinal processing and recognition of painful stimuli. This is consistent with the localization of A3AR in thalamic nuclei (Yaar et al. 2002) where they may play a role in processing nociceptive information. 

A first comment is that experimental protocols and genetic backgrounds often vary among laboratories. Obvious discrepancies (as for example different results in mu receptor knockout mice following DPDPE ICV in the tail flick and hot plate tests across laboratories, see Table 4, right column upper part) occur for technical reasons and complicate the overall picture. Despite this methodological aspect, however, several conclusions can be drawn from Table 4 ... 

The selectivity of currently used delta agonists may not be sufficient to avoid mu receptor activation in vivo. As an example, one study showed that DPDPE (selectivity delta/mu 100-fold) injected either ICV or ITH was less active in the mu receptor mutant than deltorphin (selectivity mu/delta 10,000-fold) [60]. This suggests that, in WT mice the less delta selective compound recruits mu receptors to produce analgesia in the tail flick and hot plate tests under their experimental conditions. 

As enkephalins are able to activate both deltai and delta2 receptors, their respective roles in CCK release have also been investigated. As previously mentioned, the analgesic responses obtained in the hot plate test and resulting from the protection of endogenous enkephalins are predominantly associated with mu receptor stimulation [26,83]. Nevertheless, it has been shown that the antinociceptive effects observed in this test in mice following... 

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