PERIOD3 (PER3) gene expression differs between ADHD and healthy controls after norepinephrine exposal: An ex-vivo study with human dermal fibroblasts

Introduction:

Human dermal fibroblasts HDF were obtained via skin biopsy from healthy controls (HC) (3 men, 1 woman; 42.00 ± 15.38 years, mean ± SD) and volunteers suffering from ADHD (1 man, 3 women; 38.75 ± 8.15 years, mean ± SD). Cells were cultivated at 37 °C and 5% CO2. All participants completed the Multiple-Choice Word Test (IQ score: HC: 115.25 ± 10.04, mean ± SD; ADHD participants:110.25 ± 17.01, mean ± SD, n.s), German Morningness-Eveningness-Questionnaire (D-MEQ Score: HC: 50.00 ± 3.74, mean ± SD; ADHD participants: 53.50 ± 9.54, mean ± SD, n.s) and Wender Utah Rating Scale, German short-version (WURSk Score: HC: 13.75 ± 9.98, mean ± SD; ADHD participants: 31.75 ± 6.94, mean ± SD, p = 0.025). HDF were incubated for 24h with 0.1 or 1µM norepinephrine (NE) followed of dexamethasone synchronization. HDF without NE incubation were used as negative control. After synchronization sampling was performed every forth hour for a period of 28 hours. CLOCK, BMAL1, CRY1, PER1/2/3 gene expression was measured by qRT-PCR. Statistics were calculated using SPSS.

Results:

BMAL1 and PER2 showed rhythmicity in all groups (p < 0.01, CircWave) whereas for CLOCK (all groups), CRY1 and PER3 (ADHD participants with 1µM NE) and PER1 (HC with 0.1µM NE and all ADHD participants) was not present (p > 0.05, CircWave).

In HC 0.1µM NE and 1µM NE showed similar effects. However, BMAL1 and PER2/3 expression was phase shifted with significant differences compared to negative controls (BMAL1 ZT24 p = 0.001; PER2 ZT24 p = 0.003; PER3 ZT12 p = 0.002). Furthermore, in the ADHD participants PER1 (with 1µM NE ZT20 p = 0.008) and PER3 (with 0.1µM NE ZT4 p = 0.002) expression is altered. 1µM NE incubation in the ADHD participants altered PER3 (ZT 12 p = 0.003) compared to 1µM NE HC.

Conclusion:

Our results suggest that NE may influence the circadian rhythm in human dermal fibroblasts.