Intrinsic optical signal imaging 
of glucose-stimulated insulin secreting β-cells

Abstract

Simultaneous monitoring of many functioning β-cells is essential for understanding β-cell dysfunction as an early event in the progression to diabetes. Intrinsic optical signal (IOS) imaging has been shown to allow high resolution detection of stimulus-evoked physiological responses in the retina and other neural tissues. In this paper, we demonstrate the feasibility of using IOS imaging for functional examination of insulin secreting INS-1 cells, a popular model for investigating diabetes associated β-cell dysfunction. Our experiments indicate that IOS imaging permits simultaneous monitoring of glucose-stimulated physiological responses in multiple cells with high spatial (sub-cellular) and temporal (sub-second) resolution. Rapid IOS image sequences revealed transient optical responses that had time courses tightly correlated with the glucose stimulation.

Stimulus-evoked outer segment changes in rod photoreceptors

“…10 Stimulus-evoked IOSs correlated with action potentials and postsynaptic potentials have also been detected in excitable neural tissues 56,57 and endocrine cells. 58,59 Biophysical sources and physiological mechanisms of the IOSs in neural tissues have been explored by several research groups. 56,57,[60][61][62][63] Multiple physiological processes, such as neurotransmitter secretion, 64 reorientation of membrane proteins and phospholipids, 56,57,65 and refractive index change of neural tissues 66 during neural activation, might contribute to the observed IOSs observed in neural tissues.…”

En face optical coherence tomography of transient light response at photoreceptor outer segments in living frog eyecup

“…Stimulus-evoked IOSs have been detected in the retina, neural tissues [10–13] and other excitable cells [14, 15]. Several imaging techniques, including fundus cameras [16, 17], AO ophthalmoscopes [18–20], OCT imagers [21–23] have been explored for functional IOS imaging of the retina.…”

Functional imaging of glucose-evoked rat islet activities using transient intrinsic optical signals

“…The same imaging system has been used to detect IOSs in individual INS-1 cells [14] and retinal neurons [15–17]. During the IOS recording, the islet was continuously illuminated by the NIR light source; two doses (2.75mM and 5.5mM) of glucose step change were used to stimulate the islet.…”

“…Dynamic IOS imaging disclosed dynamic optical changes, which might result from cellular (i.e. swelling or shrinking change of the cell body) [14] and/or sub-cellular (e.g. nuclear infoldings) [19] changes, associated with the glucose stimulation.…”