Changes in the levels of different ions in the eggshell gland lumen following p,p'-DDE-induced eggshell thinning in ducks.

Abstract

Eggshell thinning in ducks was induced by administration of p,p'-DDE in the diet (40 mg/kg food) for 45 days. This treatment resulted in a 19% reduction of the Eggshell Index (EI). Shells from calcifying eggs obtained at the time of slaughter showed a 36% reduction of EI. Prostaglandin synthesis by a homogenate of eggshell gland mucosa from p,p'-DDE-treated ducks was reduced by 24%. HCO3(-)-stimulated ATPase activity by a homogenate of eggshell gland mucosa from p,p'-DDE-treated ducks was not significantly changed. The calcium content of eggshell gland mucosa was increased to 127% in p,p'-DDE-treated ducks. p,p'-DDE-treated ducks showed profound changes in the shell gland luminal content of several ions. Calcium (-43%), sodium (-15%), potassium (-15%), bicarbonate (-33%) and chloride (-29%) were all significantly reduced in p,p'-DDE-treated ducks. The content of phosphate was unchanged. These findings are discussed in relation to a proposed mechanism for p,p'-DDE-induced eggshell thinning that involves inhibition of prostaglandin synthesis in eggshell gland mucosa.