The Effect of <Emphasis Type="Italic">para</Emphasis>-Aminobenzoic Acid on Apoptosis Processes in the Adult Rat Conjunctiva and Corneal Epithelium in vivo after Hypobaric Hypoxia

The initial stages of apoptotic damage to the conjunctiva and corneal epithelium, in the renewing cell populations of the eye has been studied in adult rats exposed to acute hypobaric hypoxia in vivo, and the effect of para-aminobenzoic acid (PABA) administered as the Aktipol pharmaceutical preparation (0.007% PABA) has been assessed in this experimental setup. Apoptotic damage to cell DNA was aggravated after two instances of hypoxia, and this change was accompanied by an increase in the intensity of the regenerative process inferred from the expression levels of phosphorylated histone pH3, a mitotic cell marker, and phosphorylated histone γ-H2AX, a DNA repair marker. Parabulbar injection of Aktipol 24 h before hypoxia has been shown to block development of the apoptotic process and to maintain a physiologically normal level of apoptosis, and thus the preparation exerted a protective effect in hypoxia.