The effect of streptozotocin on the secretory activity of ameloblasts in rat incisor as revealed by radioautography after3H‐proline administration

摘要

AbstractThe effect of a diabetogenic dose of streptozotocin on the secretory activity of ameloblasts was investigated in the rat incisor by radioautography. One group of male Sprague‐Dawley rats was injected intravenously with streptozotocin in citrate buffer (pH 4.5). One hour later, this group was again injected intravenously with3H‐proline (2 mCi/kg). A control group of animals was injected with3H‐proline only. All the animals were sacrificed in groups of three at 5 min, 1 h, 2 h, 4 h and 8 h after3H‐proline injection by perfusion with 3 phosphate‐buffered formaldehyde followed by an additional perfusion with 2.5 phosphate‐buffered glutaraldehyde. The incisors were extracted with the jaws, demineralized, and prepared for radioautographic observations and analysis. The principal effects of streptozotocin were as follows: There was an inhibition of3H‐proline incorporation into the secretory ameloblasts at 5 min after injection. This was followed by a larger uptake and a slower passage of the label out of the cells into the enamel matrix than that seen in the control sample. Finally, there was a slower secretion of labeled proteins out of Tomes' processes between 1 and 4 h after injection.Therefore, streptozotocin had a temporary inhibitory effect on the incorporation and secretion of3H‐proline by the secretory ameloblasts of the rat incisor. This effect was present for about 4 h and was completely reversed 9 h after streptozo