A Rat Dry Eye Model with Lacrimal Gland Dysfunction Induced by Scopolamine

The process of developing a dry eye animal model is a long one. It requires continuous subcutaneous injection of scopolamine in the hind legs of mice to suppress the secretion of the lacrimal gland in the eyes. So experimenters need to have in enough patience to administer the medication regularly over along period of time.

Our protocol is a very useful method that can created different degrees of dry eye models based on different drug concentrations. It can make it easier for the future researchers to study the treatment of dry eye disease. Our team will continue to explore the field of lacrimal gland regeneration.

We're very excited to work on reconstructing 3D organoids and conducting transplantation experiments. Our ultimate goal is to develop more advanced and efficient treatment options for individuals suffering from dry eye syndrome. To begin, hold a rat's body steady and stretch its hind leg.

Swab the injection site with alcohol. Then, insert a one milliliter syringe, equipped with a 26 gauge needle, at the base of the skin fold, between the thumb and finger. Pull the syringe plunger to aspirate the needle.

Remove and reposition the needle if necessary. Inject 0.5 milliliters of 0.9%sodium chloride, with or without scopolamine hydrobromide, in a single steady motion. To perform the tear secretion test, first cut half of a filter paper strip along the center line.

Trim the head of the strip to make it smooth. Place the filter paper strip on the outer one-third of the conjunctival sack of the lower eyelid of the rat. After five minutes, use tweezers to clamp the filter paper strip into a micro centrifuge tube.

Place a mark on the wall of the tube to record the tear volume. To stain the cornea of the rat's eye, drop 0.5 microliters of 0.5%fluorescein sodium solution into the inferior conjunctival sac of each eye. After three minutes, observe the cornea under blue light.

Take the bulbar conjunctiva from the eyes of a euthanized rat. Excise the cornea from the right side of each rat and fix it immediately in 4%paraformaldehyde. Cut out the cephalic epidermis from the subcutaneous tissue along the line, connecting the ear and the outer eye corner.

Then expand the incision to both sides and isolate the yellowish extra orbital gland. Next, remove the rat's fur completely and separate the extra orbital gland with 0.9%sodium chloride solution. The tear secretion of the scopolamine group was significantly reduced.

Scopolamine did not cause any corneal epithelial defects as evidenced by the absence of corneal staining. The corneal epithelium of the scopolamine groups was relatively thinner than the control group. The 7.5 group also showed loose intracellular connection and vacular structure in the basal layer.

The control groups had significantly thicker corneal epitheliums. Scopolamine appeared to cause inflammatory changes in the lacrimal glands, indicative of functional lacrimal gland damage. Reduced mucinous substance was observed in groups 2.5 and 5, with free lymphocyte infiltration.

Additionally, group 7.5 showed irregular arrangement of the cells with irregularly shaped epithelial cells. Scopolamine also caused morphological changes in the conjunctiva.