PT Journal AU Bracci, M Manzella, N Copertaro, A Staffolani, S Strafella, E Barbaresi, M Copertaro, B Rapisarda, V Valentino, M Santarelli, L TI Rotating-shift nurses after a day off: peripheral clock gene expression, urinary melatonin, and serum 17-β-estradiol levels SO Scandinavian Journal of Work, Environment & Health PD 5VL PY 2014 BP 295 EP 304 IS 3 DI 10.5271/sjweh.3414 WP https://www.sjweh.fi/show_abstract.php?abstract_id=3414 DE 6-sulfatoxymelatonin; breast cancer; chronotype; circadian rhythm; clock gene; clock gene expression; night work; nurse; peripheral clock gene expression; rotating shift; serum 17-β-estadiol; shift work; shift worker; urinary melatonin; work schedule tolerance SN 0355-3140 AB '

'

OBJECTIVE ': 'Impairment of clock gene expression and changes in melatonin and 17-β-estradiol levels may constitute biological alterations underlying the increased risk of breast cancer among shift workers. The aim of this study was to compare levels of selected core clock gene expression, 6-sulfatoxymelatonin (aMT6s), and 17-β-estradiol between rotational shift work (SW) and daytime (DT) workers after a day off.

'

'

METHODS ': 'The cross-sectional study comprised 60 nurses with ≥2 years of SW and 56 permanent DT nurses. Transcript levels of circadian genes BMAL1, CLOCK, NPAS2, CRY1, CRY2, PER1, PER2, PER3, and REVERBα were determined by quantitative real-time polymerase chain reaction (PCR) in lymphocytes. All participants were tested in the early follicular phase of the menstrual cycle. Samples were collected at the beginning of the morning-shift after a regular night’s sleep on a day off. Chronotype and sociodemographic characteristics were also evaluated.

'

'

RESULTS ': 'We found a significantly higher expression of BMAL1, CLOCK, NPAS2, PER1, PER2, and REVERBα and a lower expression of PER3, CRY1 and CRY2 among SW compared to DT nurses. SW participants did not demonstrate a significant difference in aMT6s levels, but they did show significantly higher 17-β-estradiol levels compared to DT nurses. Multiple linear regression analysis confirmed the role of SW on expression of BMAL1 (β 0.21, P=0.040), CLOCK (β 0.35, P=0.008), NPAS2 (β 0.30, P=0.012), PER1 (β 0.33, P=0.008), PER2 (β 0.19, P=0.047), PER3 (β -0.27, P=0.012), CRY1 (β -0.33, P=0.002), CRY2 (β -0.31, P=0.005), REVERBα (β 0.19, P=0.045), and on 17-β-estradiol levels (β 0.32, P=0.003). The analysis also confirmed the role of chronotype as an independent factor for PER1 (β 0.48, P=0.001) and PER2 (β -0.22, P=0.022) expression, and 17-β-estradiol levels (β 0.26, P=0.011).

'

'

CONCLUSIONS ': 'Rotating SW nurses show alterations in peripheral clock gene expression and 17-β-estradiol levels at the beginning of the morning shift after a day off.

ER