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^*Department of/ Biological Sciences. Faculty of Science, Kuwait University, P.O.Box 5969 safat 13060 Kuwait.

^**Zoology Department, Faculty of Science. Alexandria University, Alexandria. Egypt
* E-mail: alnaqeeb@ kuc01 kuniv.edu.kw   

ABSTRACT

Harderian glands exist in the orbits of most terrestrial vertebrates and are particularly prominent in rodents. Several functions have been ascribed to the gland such as lubrication of the eye. a source of pheromones and thermoregulatory lipids and as a part of the retinal-pineal axis. In the present study, treatment of rats with a single high dose (300 ىg/ kg body weight) of carbamylcholine chloride (a cholinergic secretagogue) resulted in the secretion of bloody tears (porphyrin pigment) from the Harderian gland. Also, carbamylcholine treatment induced significant elevation in the activity of the lysosomal enzymes acid phosphatase and â-glucuronidase 10 min after injection. The activity of both enzymes returned to their normal levels 2 hours after injection. Parallel changes to lysosomal enzymes activity were observed in the gland ultrastructure. Carbamylcholine treatment induced deformity of the epithelial cells, primarily type A cells, 10 min after injection. Most of the cells returned to their normal appearance 2 hours after treatment, by which time the activity of enzymes were back to their normal levels. One of the most striking features was the appearance of cytoplasmic slashes. These structures have never been reported in the rat Harderian gland, in carbamylcholine treated animals. The presence of cytoplasmic slashes relates, in the gerbil, to either porphyrin or lipid synthesis, thus being suggestive of possibly similar roles in the secretory epithelium of the rat Harderian gland.

Keywords: Carbamylcholine; Harderian gland; lysosomal enzyme: rat; ultrastructure.