Glycogen Accumulation in Reissner's Membrane Following Chemical Sympathectomy with 6-Hydroxydopamine

Abstract

Rats were chemically sympathectomized by injecting them with 6-hydroxydopamine repeatedly during early postnatal development. Litter mates left untreated or injected with the vehicle only were used as controls. Inner ear tissues from a series of treated and control rats 11-72 days of age were fixed, then microdissected and prepared by usual methods for transmission electron microscopical study. Control rats 11 days of age showed accumulation of glycogen particles in Reissner's membrane, particularly in the epithelial cell layer near its attachment to the spiral limbus. The epithelial cells in that region also had rough endoplasmic reticulum with greatly widened cisternae containing a granular substance. The glycogen was not present after 11 days and the cisternae diminished in size with further postnatal development. The epithelial cells of the membrane in controls of all ages had intercellular clefts that were closed at the endolymphatic surface by zonulae occludentes, open narrowly at their basal end, and variously dilated in between. Coated vesicles were common at apical and lateral cell borders as well as intracellularly. Treated rats, on the other hand, showed an accumulation of glycogen particles in the epithelial cells that increased between 11 and 32 days and persisted in some cells at 72 days. The glycogen particles, β in type, were electron-dense, -150-300 Å in diameter, and often aggregated in large masses, particularly in the lateral cell regions. Concomitantly with glycogen accumulation, coated vesicles diminished numerically and the intercellular clefts narrowed, becoming of uniformly narrow dimensions by 32 days. An upturn in the number of coated vesicles and a widening of the intercellular clefts occurred by 72 days. The results are interpreted as indicating that the epithelial cells of Reissner's membrane have an energy dependent, coupled ion/water transport capability that is ordinarily supported by glucose metabolism. It appears that the glucose metabolism is in turn regulated by catecholamines, suggesting the existence of β-adrenergic receptors on the epithelial cells of Reissner's membrane.