Diurnal variation and distribution of grooming behavior in captive common marmoset families (Callithrix jacchus)

Grooming is an important social activity among primates. In an investigation of its diurnal distribution, all grooming episodes (self-and allo-) were recorded in three families of captive common marmosets (Callithrix jacchus) kept under natural environmental conditions at hourly intervals for periods of 20 min from 05:00 to 18:00 h, for three consecutive days a week for four weeks. The three families were composed of a reproductive pair and their offspring, with 8, 8 and 7 individuals, respectively. No significant variations were detected within families in terms of days or weeks. However, one family did perform more grooming than the others. The frequency of grooming episodes per hour/per family was higher during the period from 08:00-12:00 h, with acrophases narrowly distributed near 10:00 h, (Family 1 = 10:32 ñ 00:33 h; Family 2 = 10:11 ñ 00:13 h; Family 3 = 09:45 ñ 00:14 h) and lower frequencies were observed at the beginning and end of the active period. The differences between families are probably related to the social dynamics of the individual groups and not to their size

Circadian variation of methyleugenol anesthesia in albino rats

In Wistar rats synchronized to a 12-h light/12-h dark cycle (lights on from 08:00 to 20:h), the ip injection of methyleugenol (200 mg/Kg) at 08:00, 12:00 and 16:00 h significantly increased the sleeping time (time between loss and recovery of righting reflex) when compared to animals anesthetized at 20:00, 24:00 and 04:00h. These data provide another example of the importance of circadian rhythms in biological systems and their practical relevance to pharmacology