Phototransduction for human melatonin suppression (original) (raw)
2002, Journal of Pineal Research
AI-generated Abstract
Human adult males were exposed to combinations of two illuminances and two broadband spectral power distributions over the course of four night-time sessions. Results showed that melatonin suppression is dominated by short visible wavelengths (420-520 nm), consistent with recently published studies. Although the authors of these recent studies suggest that a novel opsin underlies melatonin suppression, the present paper offers a more conservative interpretation of the data based on what is known about existing photoreceptors and associated neuroanatomy and neurophysiology. All sessions began at 22:00 hr and ended at 07:00 hr the following morning. The first light exposure always started at 23:00 hr. Blood samples were drawn every hour following dark and light exposures. Samples were spun in a centrifuge at 3200 rpm (approximately 1000 g) for 10 min and separated plasma was frozen at -25°C. Frozen samples were sent to an independent laboratory (Pharmasan Inc., Osceola, WI, USA) for melatonin radioimmunoassay. Fig. 2 shows the mean baseline melatonin concentrations and the mean experimental melatonin concentrations, averaged across all lighting conditions for each hour. The baseline results from the present study were similar to and highly correlated (r 2 ¼ 0.87) with those from the previously reported baseline using the same methods and subjects [4]. Table 1 shows the mean melatonin suppression for each lighting condition, defined as the difference between the melatonin concentration immediately following exposure to light and the concentration just before exposure, expressed as a percentage of the concentration before exposure. These results are plotted as a function of scotopic illuminance and S-cone illuminance in Fig. 3. Also plotted in Fig. 3 are the best fitting compressive asymptotic functions to the data having the form [7]:
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.