DEVELOPMENT OF CATAPLEXY IN GENETICALLY NARCOLEPTIC DOBERMANS

Forty-two genetically narcoleptic Doberman pup. pies [20 pure narcolep tic (N) puppies (from four narcoleptic x narcoleptic crosses) and 22 b ackcross narcoleptic (BN) puppies (from six narcoleptic x heterozygous crosses)] were systematically observed during the developmental perio d (4-24 weeks) to assess the age at onset and severity of cataplexy, a pathological manifestation of REM sleep atonia seen in narcolepsy. Th e mean age of onset of cataplexy was 9.69 +/- 1.15 weeks, with a media n age of 7 weeks. The severity of cataplexy increased with age and rea ched a plateau at around 16-24 weeks. The effects of cross type (N vs BN) and sex on the development of cataplexy were analyzed. There was n o difference in severity males had more severe cataplexy than males (P = 0.01), and this trend was preserved in five of the six litters that had both male and female puppies. These results suggest that the path ophysiological process in genetic canine narcolepsy emerges duping the early developmental, period and that it may involve a differential de velopment in males and females. Furthermore, our results revealed that cataplexy onset corresponds Its the emergence of adult-like REM sleep and to previously reported neuroanatomical and neurochemical abnormal ities in canine narcolepsy. (C) 1998 Academic Press.