Abstract

The effects of the pulp and seeds of Carica papaya (Honey dew variety) on the visual relay centres in rats were investigated. Thirty rats were randomly grouped into three groups (A, B, and C) of ten rats each. Each of the rats in groups A, B and C were fed with 8.50 g of standard rat pellet, 8.50 g of 1:1 mixture of C. papaya pulp and the standard rat chow, and 8.50 g of 1:1 mixture of C. papaya seeds and standard rats’ chow, twice daily, respectively. Twenty-four hours after the last administration, the rats were sacrificed by cervical dislocation, the brain was removed, superior colliculus (SC) and lateral geniculate body (LGB) were carefully excised. Fraction of the SC and LGB meant for quantitative enzyme histochemistry were homogenized in sucrose solution and processed accordingly for the activities of lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD) and acetylcholinesterase (AChE) while the fraction of the SC and LGB meant for histological and immunohistochemical analysis were fixed in 10% formol-calcium solution and were processed for paraffin embedding, respectively. The histological, histochemical and immunohistochemical studies revealed that C. papaya seeds caused neuronal degeneration and disruption in the visual relay centres of the treated rats. The activity of G6PDH was increased in the SC and LGB of rats in groups B and C, and there was statistically significant (P<0.05) inhibition in the activity of AChE in both the SC and LGB of rats in group C.

Key words: Quantitative histochemistry, histology, Carica papaya, superior colliculus, lateral geniculate body, 10% formol calcium.