Effect of prior sporidesmin intoxication on the pancreopathy associated with zinc oxide toxicity.
OBJECTIVE
To demonstrate the effect of prior sporidesmin-induced liver injury on the pancreopathy of zinc-induced toxicity.


METHODS
Four groups, each of 15 sheep, were given 2 x 2 treatments of sporidesmin (0.3 mg/kg bodyweight spread over 3 consecutive days prior to zinc) and zinc (200 mg Zn/kg bodyweight as ZnO spread over 24 days) starting 4 days after the end of sporidesmin dosing. Liver and pancreatic changes were assessed by serum enzyme changes (serum amylase and gamma glutamyltransferase) or scoring for injury at post-mortem examination (hepatopathy) or by histopathological examination (pancreopathy).


RESULTS
Minor pancreatic injury was caused by the administration of zinc. The pancreopathy associated with zinc oxide toxicity was significantly greater in those sheep receiving zinc after the sporidesmin-induced injury. Pathological and body weight changes associated with sporidesmin toxicity also occurred in both groups dosed with sporidesmin. These were slightly less in the group of sheep receiving zinc after the sporidesmin challenge than in those receiving sporidesmin alone.


CONCLUSIONS
Zinc-induced pancreatic injury is greater if the zinc is administered after liver injury has been caused by sporidesmin. Only minor protection is given by zinc if it is administered after the challenge with sporidesmin.


CONCLUSIONS
The safety margin for the use of zinc is reduced if zinc is administered after significant liver injury has been caused by prior exposure to high Pithomyces chartarum spore counts.
Smith
B L
BL
Toxinology and Food Safety Research Group, Ruakura Research Centre, New Zealand Pastoral Agriculture Research Institute, Hamilton.
Embling
P P
PP