Effect of retinoic acid on the nitrergic innervation of meibomian glands in rats

Abstract

The purpose of this study was to investigate the effect of prenatal administration of retinoic acid (RA) on the development of nicotinamide adenine dinucleotide diaphorase (NADPH-d) positive structures in the rat Meibomian glands. One mg/kg of RA was applied to pregnant Wistar rats intraperitonaelly during the gestational period in each of the 12th-14th embryonic days (totally 3 mg/kg). Sections of the central upper eyelids were investigated in rat pups on the 14th postnatal day. They were processed histochemi-cally for NADPH-d, to study the presence and distribution of nitric oxide synthase (NOS) pos-itive nerve structures. NADPH-d staining of Meibomian glands was compared in two groups of rat pups. In the control group, eyelids of 14 day-old rats were studied with no experimental intervention. The second group consisted of rat pups which were prenatally administered the excess of RA. Histochemical analysis of control eyelids revealed numerous NADPH-d well-stained acini of Meibomian glands arranged tightly into groups. Intensively stained vessels and NADPH-d/NOS-positive nerve fibers bor-dered acini of Meibomian glands. These struc-tures were present in the submucosal layer as well. The analysis of RA group showed less numerous, shrunken acini of Meibomian glands that were seen not only smaller in size, but also in density of their staining and the amount of nitrergic nerve fibers around acini were considerably lowered. In the submucosa differences were noticed compared to the con-trol group, there were numerous NADPH-d stained vessels accompanied by NADPH-d/NOS-positive nerve fibers. The excess of RA during the prenatal period may influence on the devel-opment and morphology of NADPH-d positive structures of rat's Meibomian glands.©A. Bolekova et al.,2012.