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By inbreeding we have obtained two sublines of Sprague-Dawley rats which differ significantly in spontaneous mean yawning frequency (MYF). In generation F21 of the high-yawning (HY) subline MYF was 21.5 yawns/h (y/h) in males and 1.95 y/h in females, at the age of 2 months. In the low-yawning (LY) subline, in generation F16 the MYF was 0.9 y/h in males and(More)
This report describes a new inherited disorder of myelination in the rat, named taiep, in which failure of normal myelination of the CNS and subsequent demyelination result in a progressive neurological disturbance. At two months of age, myelin is present throughout the spinal cord, but is immature in the fasciculus gracilis and corticospinal tracts despite(More)
On two occasions, chloralkali workers were investigated with regard to personal air mercury exposure, blood mercury and urinary mercury. The first investigation (13 workers, 2 weeks) was made at an exposure above the threshold limit value (64 microgram/m3, range 36--112), the second (16 workers, 8 weeks) at a lower exposure (23 microgram/m3, range 15--43).(More)
A spontaneous neurological mutation was detected in a colony of Sprague Dawley rats. The animals developed a progressive neurological syndrome characterized by tremor (which appeared at the age of 1 month), ataxia (at 4 months), immobility episodes (after 5-6 months), audiogenic seizures and hindlimb paralysis (after 10 months). Cross breeding experiments(More)
This work compares the sensitivities of high-yawning (HY) and low-yawning (LY) sublines of Sprague-Dawley rats to dopaminergic and cholinergic yawning-inducing drugs. HY animals are significantly more sensitive to apomorphine and (-)3PPP than LY animals. Physostigmine is a less effective yawning-inducer in HY than in LY rats. With pilocarpine no differences(More)
In a Sprague-Dawley-derived line of rats, selectively bred to establish a high incidence of spontaneous yawning behavior, the simultaneous and systematic monitoring of yawning and penile erections, during observation periods of one hour, demonstrates a linear correlation between these two behavioral patterns. Dose-effect curves of yawning and penile(More)
The possible interaction between cholinergic and dopaminergic influences in the induction of yawning behavior in the rat is explored resorting to several experimental approaches: comparison of the ontogeny of yawning behavior induced by physostigmine (0.15 mg/kg) and apomorphine (0.05 mg/kg); simultaneous injection of both drugs; "crossed blocking"(More)
The effect of feeding schedules on the daily rhythm in spontaneous yawning activity was studied in high yawning (HY) Sprague-Dawley rats. If the animals are fed ad libitum and changed from a standard 12-12 light-dark (LD) illumination regime to constant light (LL), the normal predark circadian peak in yawning disappears, to be replaced, after 3 weeks, by(More)