Species difference in intestinal drug metabolising enzymes in mouse, rat and hamster and their inducibility by masheri, a pyrolysed tobacco product.

Activities of several drug metabolising enzymes in the small intestine were investigated in Swiss mice, Sprague Dawley rats and Syrian Golden Hamsters fed 10% masheri, a pyrolysed tobacco product, in diet, for 20 months. The basal levels of enzymes in proximal (PI), medium (MI) and distal (DI) parts of the intestine in the three species were similar. However, the levels of cytochrome P-450, benzo(a) pyrene hydroxylase (B(a)OH) and glutathione S-transferase (GST) were highest in hamsters followed by rat and mice. Upon treatment with masheri, significant induction of cytochrome P-450 and B(a)PH was observed in PI and DI of all the three species. However, GSH and GST was depleted upon masheri treatment in all the three species again only in proximal and distal parts of the intestine. Thus increase in activating enzymes together with depletion in GSH-GST system upon exposure could be an important factor in the susceptibility of the small intestine to hazardous xenobiotic exposure.

Short-term and long-term effects of brown and black masheri (pyrolysed tobacco product) on vitamin A and vitamin C levels in mice and hamsters.

The short-term and long-term effects of two most commonly used brown and black masheri were studied in Swiss mice and Syrian golden hamsters. In short-term studies, both the types of masheri extracts (ME) at 3/4 LD50 dose given ip did not have any effect on either liver or plasma vitamin C levels (both species). However, a decrease in liver vitamin A was observed only in hamsters injected with black ME. Similar effect was not observed in mice injected with both the types of masheri extracts. In long-term studies, when both the types of masheri were fed through diet at 10% level for 20 months, no effect was observed on hepatic or plasma vitamin C levels in mice (both sexes), while an increase in vitamin C levels was observed in black masheri diet fed hamsters. A depletion in liver vitamin A was observed in hamsters fed both the types of masheri. Such an effect was observed only in black masheri diet fed Swiss mice (both sexes) and brown masheri diet fed Swiss females.