Structure and functional connections of presynaptic terminals in the vertebrate retina revealed by activity-dependent dyes and confocal microscopy

Miller, RF Fagerson, MH Staff, NP Wolfe, R Doerr, T Gottesman, J Sikora, MA Schuneman, R

Rf. Miller et al., Structure and functional connections of presynaptic terminals in the vertebrate retina revealed by activity-dependent dyes and confocal microscopy, J COMP NEUR, 437(2), 2001, pp. 129-155

60

INGLESE

Article

Neurosciences & Behavoir

JOURNAL OF COMPARATIVE NEUROLOGY

0021-9967 → ACNP

437

2

2001

129 - 155

ISI

0021-9967(20010820)437:2<129:SAFCOP>2.0.ZU;2-Q

The fluorescent dyes sulforhodamine 101 (SR 101) and FMI-43 were used as ac tivity-dependent dyes (ADDs) to label presynaptic terminals in the retinas of a broad range of animals, including amphibians, mammals, fish, and turtl es. The pattern of dye uptake was studied in live retinal preparations by u sing brightfield, fluorescence, and confocal microscopy. When bath-applied to the retina-eyecup, these dyes were avidly sequestered by the presynaptic terminals of virtually all rods, cones, and bipolar and amacrine cells; ga nglion cell dendrites and horizontal cells lacked significant dye accumulat ion. Other structures stained with these dyes included pigment epithelial c ells, cone outer segments, and Muller cell end-feet. Studies of dye uptake in dark- and light-adapted preparations showed significant differences in t he dye accumulation pattern in the inner plexiform layer (IPL), suggesting a dynamic, light-modulated control of endocytotic activity. Presynaptic ter minals in the IPL could be segregated on the basis of volume: bipolar varic osities in the IPL were typically larger than those of amacrine cells. The combination of retrograde labeling of ganglion cells and presynaptic termin al labeling with ADDs served as the experimental preparation for three-dime nsional reconstruction of both structures, based on dual detector, confocal microscopy. Our results demonstrate a new approach for studying synaptic i nteractions in retinal function. These findings provide new insights into t he likely number and position of functional connections from amacrine and b ipolar cell terminals onto ganglion cell dendrites. (C) 2001 Wiley-Liss, In c.