As both a photoreceptor and pacemaker in the avian circadian clock system, the pineal gland is crucial for maintaining and synchronizing overt circadian rhythms in processes such as locomotor activity and body temperature through its circadian secretion of the pineal hormone melatonin. In addition to receptor presence in circadian and visual system structures, high-affinity melatonin binding and receptor mRNA are present in the song control system of male oscine passeriform birds. The present study explores the role of pineal melatonin in circadian organization of singing and calling behavior in comparison to locomotor activity under different lighting conditions. Similar to locomotor activity, both singing and calling behavior were regulated on a circadian basis by the central clock system through pineal melatonin, since these behaviors free-ran with a circadian period and since pinealectomy abolished them in constant environmental conditions. Further, rhythmic melatonin administration restored their rhythmicity. However, the rates by which these behaviors became arrhythmic and the rates of their entrainment to rhythmic melatonin administration differed among locomotor activity, singing and calling under constant dim light and constant bright light. Overall, the study demonstrates a role for pineal melatonin in regulating circadian oscillations of avian vocalizations in addition to locomotor activity. It is suggested that these behaviors might be controlled by separable circadian clockworks and that pineal melatonin entrains them all through a circadian clock.
|Number of pages||11|
|Journal||Journal of Biological Rhythms|
|State||Published - Apr 2012|
Bibliographical noteFunding Information:
We thank Jennifer O’Brien for data collection; Jiffin Paulose, Jaclyn Malloy, and Ye Li for stimulating discussions; and Melissa Whitfield-Rucker for animal facility and administrative support. This work was supported by the University of Kentucky and NIH P01 NS 39546 to VMC.
- Taeniopygia guttata
- circadian rhythm
- locomotor activity
- zebra finch
ASJC Scopus subject areas
- Physiology (medical)