Faculty Collaboration Database

Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles. Chronobiol Int 2012 Nov;29(9):1206-15

Date

09/26/2012

Pubmed ID

23003567

Pubmed Central ID

PMC4917013

DOI

10.3109/07420528.2012.719965

Scopus ID

2-s2.0-84867316101 (requires institutional sign-in at Scopus site)   17 Citations

Abstract

The daily pattern of blood-borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the DS of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within ≈ 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset and duration of nocturnal secretion.

Author List

Raiewski EE, Elliott JA, Evans JA, Glickman GL, Gorman MR

Author

Jennifer A. Evans PhD Assistant Professor in the Biomedical Sciences department at Marquette University

MESH terms used to index this publication - Major topics in bold

Animals
Circadian Rhythm
Cricetinae
Male
Melatonin
Mesocricetus
Motor Activity
Phodopus
Photoperiod
Species Specificity