EFFECT OF INDOMETHACIN ON SELECTED PROTEIN DIGESTING ENZYMES IN THE NORWAY RAT, RATTUS NORVEGICUS
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Date
2020-07
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Abstract
Rats are rodents of the genus Rattus and are commensals. They are rapid breeders and tend to
breed all year round. Rats are responsible for the transmission of many diseases, are sources of
allergens and harbour fleas and ticks which are parasites that carry diseases. Rats destroy
agricultural produce, household items and documents leading to huge financial losses.
Biological and physical methods of rat control have proved inefficient, while rodenticides use
is associated with high cost, risks and dangerous side effects. Indomethacin has been shown to
lead to 100% mortality in the Norway rat experimentally, with accumulation of undigested food
in their stomach. This research therefore determined the effects of indomethacin on selected
protein digesting enzymes pepsin, trypsin and amino peptidase in rats. One hundred and fifty
female rats were randomly divided into six groups of twenty five rats each. Group A was used
as control while B, C, D, E and F served as experimental groups and were given 12.5mg/Kg,
25mg/Kg, 50mg/Kg, 100mg/Kg and 150mg/Kg of indomethacin respectively. Five rats in each
group were euthanized at intervals of one hour, two, four, eight and twelve hours from the time
of indomethacin administration. The rats were dissected and the gut contents removed. The
digesta from the stomach, duodenum and ileum were collected, centrifuged, and the
supernatants gently pipetted into sterile vials and then frozen in liquid nitrogen. The activity of
digestive enzymes in the specimens were determined by continuous spectroscopic enzyme
bioassays. Analysis of data was done by one way analysis of variance (ANOVA) while
significant difference in the means of experimental groups was determined using post hoc
ANOVA test (L.S.D). Regression analysis showed a linear relationship between indomethacin
dose and enzyme activity. The results were expressed as mean ± standard error. The results
showed that increase in dose of indomethacin administered leads to a decrease in the enzyme
activity. Pepsin activity at 12.5mg/Kg dose was 214.2±0.6µg/mol while at a dose of 150mg/Kg
the activity was 51.4±0.5µg/mol. Trypsin activity at a dose of 12.5mg/Kg, was 113.5±0.03
µg/mol while at 150mg/Kg dose the activity was 29.0±0.1µg/mol. Amino peptidase activity at
12.5mg/Kg dose was 126.5±0.04µg/mol while at 150mg/Kg dose, the activity was
33.5±0.09µg/mol. The enzyme activity is inversely proportional to the length of time taken after
indomethacin administration. Pepsin activity after one hour was 214.2±0.6µg/mol while at
twelve hours the activity was 108.8±0.4µg/mol. Trypsin activity after one hour was
113.2±0.03µg/mol while after twelve hours the activity was 55.5±0.05µg/mol. Amino
peptidase activity after one hour was 126.5±0.04µg/mol while after twelve hours the activity
was 67.8±0.03µg/mol). The mean enzyme activities in all groups were significantly different
from each other at p<0.05. The results of this study have provided better understanding of the
physiological basis of functioning of indomethacin as a rodenticide and its effects in digestion
of rats. The findings of this study should be used by government officers to educate the masses
on control of rats using indomethacin. The mechanism by which indomethacin decreases
protein digestive enzyme activity should be investigated.