Olfactory ensheathing cell membrane properties are shaped by connectivity (foto de tapa)

LORENA RELA; ANGELIQUE BORDEY; CHARLES A. GREER

GLIA

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: Malden; Año: 2010 vol. 58 p. 665 - 678

0894-1491

Olfactory ensheathing cells (OECs) have been repeatedlyimplicated in mediating plasticity, particularly in situ inthe olfactory nerve in which they support the extension ofolfactory sensory neuron (OSN) axons from the olfactory epitheliumto the olfactory bulb (OB). OECs are specializedglia whose processes surround OSN axon fascicles withinthe olfactory nerve and across the OB surface. Despite theirpurported importance in promoting axon extension, and followingtransplants, little is known about either morphologyor biophysical properties of OECs in situ. In particular,cell?cell interactions that may influence OEC function arelargely unexplored. Here, we studied OEC connectivity andmorphology in slice preparations, preserving tissue structureand cell?cell interactions. Our analyses showed thatOECs form a matrix of cellular projections surroundingaxons, unique among glia, and express high levels of connexin-43. Lucifer Yellow injections revealed selective dyecoupling among small subgroups of OECs. Two types ofOECs were biophysically distinguished with whole-cell voltage-clamp recordings: (1) with low-input resistance (Ri), linearcurrent profiles, and frequently dye coupled; and (2)with high Ri, nonlinear current profiles, and infrequent dyecoupling. Pharmacological blockade of gap junctionschanged OEC membrane properties such that linear OECsbecame nonlinear. Double recordings indicated that theappearance of the nonlinear current profile was associatedwith the loss of electrical coupling between OECs. We concludethat the diversity of OEC current profiles can beexplained by differences in gap-junction connectivity anddiscuss implications of this diversity for OEC influences onaxon growth and excitability.