The effect of Masson pine pollen on the quantitative zinc metabolism in ⁶⁵Zn-labeled growing rats

Thirty growing male Sprague Dawley rats weighing 85 g were injected with 170 kBq ⁶⁵Zn in 75 μl saline and each group of 10 animals were alloted to 3 purified diets without (control) or with addition of 6% native or 6% broken pollen from the Masson pine. All experimental diets contained 7 ppm zinc and were fed restrictively (9.4 g/day) for 17 days. Fecal and renal excretions of zinc were monitored, true absorption and endogenous fecal excretion were determined by the radioisotope dilution technique. At the end of the experiment body weight and plasma zinc concentration did not differ between treatment groups (157 g, 0.60 ppm). In animals fed pollen the hematological parameters exceeded slightly the control levels. Native and broken pollen increased total fecal zinc excretion by 53% and 38%. This was caused by a rise in the excretion of endogenous fecal zinc by 64% in both pollen groups and in the case of native pollen additionally by a depression of true zinc absorption from 96.0% (control) to 94.4%. In broken pollen true zinc absorption remained unchanged (96.0%). Renal zinc excretion did not differ between treatment groups while zinc retention was reduced by 5% in native and broken pollen.