Binocular facilitation in light‐mediated melatonin suppression?

Abstract

In humans, the production of melatonin is suppressed by light exposure. This effect is mediated by a retinal pathway involving the melanopsin-containing intrinsincally photosensitive retinal ganglion cells (ipRGCs), which exhibit maximum sensitivity to short-wavelength light. Here, based on extant and published data, we examine how signals from the two eyes are integrated in driving the suppression of melatonin by light. We find that melatonin suppression by light exposure to two eyes corresponds to a sensitivity shift by about 1.2 log units (factor ~17.4). K E Y W O R D Sbinocular integration, binocular summation, light, melanospin, melatonin suppression, non-image forming function

Sphingosine kinase 1 promotes cerebral ischemia‐reperfusion injury through inducing ER stress and activating the NF‐κB signaling pathway

“…Furthermore, we found that ER stress and inflammation response seem to be modulated by SHPK1 through the NF-κB signaling pathway. Inhibition of NF-κB could also abolish the proinflammation and fatal effects exerted by hydrogen peroxide, similar to the data obtained through silencing SHPK1 (Spitschan & Cajochen, 2019;Q. Sun et al, 2019).…”

Relative light sensitivities of four retinal hemi-fields for suppressing the synthesis of melatonin at night

“…This net suppression, or the average 1-h suppression across the four hemi-fields, was not significantly different than 24% suppression for the full-field exposure for the same level of CS according a two-tailed one sample t -test ( t 15 = 0.50, p = 0.62). This average suppression was, however, statistically different than the monocular-adjusted CS = 0.21 based upon the estimate from ( Spitschan and Cajochen, 2019 ) ( t 60 = 2.41, p < 0.05; two-tailed). This discrepancy perhaps suggests that the reduction in effective stimulus level from binocular to monocular is not quite 90% as Spitschan & Cajochen estimated, but closer to 87% or 85%, which would correspond to a CS = 0.24 or CS = 0.27, respectively.…”

“…Naturally, there would be an expected reduction in neural input to the SCN relative to viewing the luminous stimuli binocularly. Quite surprisingly, monocular viewing does not reduce the effective stimulus by 50% but, rather, by approximately 90% ( Spitschan and Cajochen, 2019 ). The full-field stimulus condition employed in the present study was calibrated to produce a binocular circadian stimulus (CS) of 0.60, corresponding to an expected 60% suppression of nocturnal melatonin after a 1-h exposure.…”

“…The full-field stimulus condition employed in the present study was calibrated to produce a binocular circadian stimulus (CS) of 0.60, corresponding to an expected 60% suppression of nocturnal melatonin after a 1-h exposure. Based upon the estimates from Spitschan and Cajochen (2019) , a 90% reduction in effective light stimulus would translate to a binocular CS = 0.21, with an expected suppression of melatonin of 21% after 1 h of light exposure. The present results showed a 24% suppression of melatonin after 1 h for the full-field stimulus condition which, following a two-tailed, one sample t -test, was not significantly different than a 21% reduction ( t 15 = 0.48, p = 0.64).…”

luox: novel open-access and open-source web platform for calculating and sharing physiologically relevant quantities for light and lighting

“…Science is a cumulative effort that requires the aggregation of studies to facilitate meta-analytic efforts and evidence synthesis (see, e.g., 27 and 45 for recent efforts to aggregate data). To enable a clear interpretation of the results and “future-proof” 46 research efforts requires adequate documentation of study conditions going well beyond current standard practice.…”