Ca²⁺-Mobilization and Cell Contraction after Muscarinic Cholinergic Stimulation of the Chick Embryo Lens

Abstract

The localization of ChAT in the differentiating fibers of the lens indicates that acetylcholine is synthesized during differentiation and modulates morphogenesis and elongation of mAChR-positive progenitor cells in the equatorial zone. The carbachol-induced contraction indicates that the embryonic muscarinic system may be involved in the regulation of cellular movements.

GABA neurotransmitter signaling in the developing mouse lens: Dynamic regulation of components and functionality

“…The responding cells in our studies may correspond to the population of chicken annular pad cells responding to muscarinic acetycholine receptor stimulation with a [Ca 2ϩ ] i rise (Oppitz et al, 2003). We suggest that GABA and Ach may operate in concert as described previously for the chick retinal ventricular zone (Pearson et al, 2002) where the two neurotransmitters act synergistically to induce [Ca 2ϩ ] i rise.…”

GAD isoforms exhibit distinct spatiotemporal expression patterns in the developing mouse lens: Correlation with Dlx2 and Dlx5

“…Striking functional and structural similarities between lens fiber cells and neurons are observed in the regulation of vesicle trafficking and the involvement of Alzheimer proteins in this process in the normal state and during disease (Frederikse and Zigler, 1998;Li et al, 2003;Frederikse et al, 2004). The spatiotemporal expression of GAD in the differentiating primary fiber cells of the mouse lens shows a remarkable similarity to the expression of choline acetyltransferase (Chat, the acetylcholine [ACh] -synthesizing enzyme) in chicken differentiating lens fibers (Oppitz et al, 2003). Especially noteworthy is the high accumulation of GAD and Chat at the apical and basal tips of the elongating fibers, suggesting that GABA may be involved in the reorganization of the cytoskeleton during fiber elongation, as suggested for ACh (Oppitz et al, 2003).…”

“…The spatiotemporal expression of GAD in the differentiating primary fiber cells of the mouse lens shows a remarkable similarity to the expression of choline acetyltransferase (Chat, the acetylcholine [ACh] -synthesizing enzyme) in chicken differentiating lens fibers (Oppitz et al, 2003). Especially noteworthy is the high accumulation of GAD and Chat at the apical and basal tips of the elongating fibers, suggesting that GABA may be involved in the reorganization of the cytoskeleton during fiber elongation, as suggested for ACh (Oppitz et al, 2003). Finally, the lens affords a unique model to study the regulation of expression and intracellular role of multiple GAD isoforms, which, similar to the developing nervous system (Szabo et al, 1994;Katarova et al, 2000;Varju et al, 2001) are sequentially induced, but are spatiotemporally segregated.…”

Identification and Functional Characterization of the Muscarinic Receptor M3 in the Human Keratinocyte Cell Line HaCaT

“…Experiments with isolated lens vesicles of the chick embryo showed that the peak reaction of muscarinic-induced calcium mobilization was followed by a contraction of the whole lens [Oppitz et al, 2003]. Addition of atropine in the plateau phase released the contraction so that the lens vesicle returned to its original diameter.…”