The Puberty Modulates the Circadian Activity Rhythm of Common Marmosets?

*Corresponding author e-mail: biopaula21@yahoo.com.br Introduction: The study of circadian activity rhythm during puberty may contribute to understand endogenous mechanisms involved with sleep-wake cycle phase delay exhibited by human adolescents. The common marmoset have been used as animal model in many biomedical researches, however the circadian rhythmicity during puberty was not yet exploited. A previous study with pubertal marmoset observed that the activity onset occurred earlier and the total activity increased after puberty onset. However, it was not possible to affirm that the results just due to puberty, because the animals were maintained under natural environmental conditions. Methods: To evaluate the effect of puberty onset on circadian activity rhythm, the activity of a pair of twins (2 females) were continuously monitored by Actiwatch (MiniMitter) between the 4th and 6th months of age. The animals were maintained with their family in a cage under artificial light conditions (light-dark cycle: 12:12h). Fecal steroids were monitored twice a week to determine the puberty onset. Results and conclusion: According with the preliminary result, the percent of spectral power of the 24 h and 8 h components remained stable along the phases. The other parameters of the motor activity did not show difference between the animals (ANOVA, p>0.05). However, the animals showed difference between the phases (one pre-pubertal and three puberty with 15 days each) in all observed parameters (ANOVA, p <0.05), except for active phase duration (ANOVA, p>0.05). The activity onset occurred earlier in the first puberal phase compared with the pre-puberal and second puberal phases (Tukey, p <0.05). Consequently, the HI was lower in this phase (Tukey, p <0.05). The activity offset occurred later and smaller in the pre-puberal phase in relation to the other phases (Tukey, p <0,05). The total activity increased along the phases (Tukey, p <0.05). There was not interaction between the animals and phases (ANOVA, p>0,05), indicating that the animals showed similar distribution in motor activity rhythm parameters at all phases of development. The changes observed in motor activity rhythm may be related to the maturation process in puberty. However, the activity onset advance observed in these twin pairs and in the previous study of our laboratory were differed from that was observed in humans, rhesus monkey females and Octodon degus , that show a delay of phase. The evaluation of more animals is necessary to confirm our hypothesis. Publication History Article published online: 16 June 2026 © 2009. Brazilian Sleep Academy. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Thieme Revinter Publicações Ltda. Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil