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Biomedical subjects

G Carli

Publications and source records attributed to G Carli.

At least 73 records · Page 4Linked to original sources

Effects of pain, morphine and naloxone on the duration of animal hypnosis.

Previous research has shown that animal hypnosis (tonic immobility) in the rabbit may be elicited in a condition of prolonged nociceptive stimulation. These experiments show that long-lasting irritative pain, produced within 15 min of formalin injection, potentiates the duration of hypnosis. Morphine, in the absence of painful stimuli, also potentiates hypnosis duration and this effect is antagonized by naloxone. Naloxone reduces hypnosis duration, but only at high doses (15 mg/kg). In a condition of irritative pain, the potentiation of hypnosis duration is abolished by naloxone (5 mg/kg). Hypnosis response is abolished in 6 out of 7 morphine-tolerant rabbits, but prolonged pain restores the response. The hypothesis that an opioid mechanism may be activated during animal hypnosis is discussed.

Animals↗

Plasma corticosterone and its relation to susceptibility to animal hypnosis in rabbits.

Plasma corticosterone has been correlated with the susceptibility to animal hypnosis in male rabbits. Subjects (Ss) were considered susceptible when mean hypnosis duration was above 30 sec or when initial duration (duration of trial 1) was greater than 0. A positive significant correlation was found between mean and initial duration. A significant difference was found between corticosterone levels in susceptible and unsusceptible Ss: higher values were associated with susceptible SS and with SS with initial duration greater than 0. These results indicate a higher susceptibility to animal hypnosis in rabbits with a more active adrenocortical system.

Animals↗

Slowly adapting receptors in cat hip joint.

1. The activity of slowly adapting joint receptors was recorded from fibers of the posterior articular nerve of the hip in deeply anesthetized cats. The static stimulus was any position of the femur maintained at least 2 min after passive displacement. Most of the fibers are active in all the positions where the femur may be placed. Modulation in the discharge frequency occurs in any axis of displacement, and higher activity is recorded at extreme positions. The maximal discharge may be reached in several positions of the femur far away from one another. 2. Adaptation to static stimuli occurs in all the receptors. Joint receptors fire at very regular, steady rates; the mean coefficient of variation was 0.079. 3. In most of the receptors, when the femur is displaced along a single axis, the frequency of discharge varies as a monotonic function of joint position. This relationship could be described either by linear and logarithmic or by linear and power functions, according to the criteria adopted to indicate the intensity of the stimulus. 4. Repetition of identical static stimuli results in different responses. 5. The static properties of the receptors are not modified by the section of periarticular muscles. 6. Hip joint receptors are able to code hip joint position.

Adaptation, Physiological↗

The projection of the posterior knee joint nerve to the cerebellar cortex.

1. In decerebrate cats, electrical stimulation of the posterior knee joint nerve evokes in the depth of the cerebellar cortex field potentials which have been identified as due to both mossy and climbing fibre inputs.2. The potentials evoked through the mossy fibres have a latency of 15-17 msec and are more widespread. Those evoked through the climbing fibres have a latency of 26-33 msec and are more restricted.3. Stimulation of the larger fibres originating from the Golgi receptors gives only a very restricted projection. When the fibres originating from the Ruffini receptors are also activated, the effect on the cerebellar cortex is more widespread.4. The results have been confirmed by recording unitary activity.

Animals↗