Entanglement between thermoregulation and nociception in the rat: the case of morphine.

In thermoneutral conditions, rats display cyclic variations of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Systemic morphine elicits their vasoconstriction followed by hyperthermia in a naloxone-reversible and dose-dependent fashion. The dose-response curves were steep with ED in the 0.

Thermoregulatory vasomotor tone of the rat tail and paws in thermoneutral conditions and its impact on a behavioral model of acute pain.

The tail and paws in rodents are heat exchangers involved in the maintenance of core body temperature (T(core)). They are also the most widely used target organs to study acute or chronic "models" of pain. We describe the fluctuations of vasomotor tone in the tail and paws in conditions of thermal neutrality and the constraints of these physiological processes on the responses to thermal nociceptive stimuli, commonly used as an index of pain.

Psychophysics of a nociceptive test in the mouse: ambient temperature as a key factor for variation.

Background: The mouse is increasingly used in biomedical research, notably in behavioral neurosciences for the development of tests or models of pain. Our goal was to provide the scientific community with an outstanding tool that allows the determination of psychophysical descriptors of a nociceptive reaction, which are inaccessible with conventional methods: namely the true threshold, true latency, conduction velocity of the peripheral fibers that trigger the response and latency of the central decision-making process.

Methodology/principal Findings: Basically, the procedures involved heating of the tail with a CO(2) laser, recording of tail temperature with an infrared camera and stopping the heating when the animal reacted.

Peripheral and central determinants of a nociceptive reaction: an approach to psychophysics in the rat.

Background: The quantitative end-point for many behavioral tests of nociception is the reaction time, i.e. the time lapse between the beginning of the application of a stimulus, e.