title: The effect of streptozotocin on the secretory activity of ameloblasts in rat incisor as revealed by radioautography after 3H-proline administration.
abstract: The 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 with 3H-proline (2 mCi/kg). A control group of animals was injected with 3H-proline only. All the animals were sacrificed in groups of three at 5 min, 1 h, 2 h, 4 h and 8 h after 3H-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 of 3H-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 of 3H-proline by the secretory ameloblasts of the rat incisor. This effect was present for about 4 h and was completely reversed 9 h after streptozotocin injection.
mesh_terms: D000565:Ameloblasts / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D003746:Dental Enamel Proteins / Q000378:metabolism; D007180:Incisor / Q000187:drug effects / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013311:Streptozocin / Q000633:toxicity*
chemical_list: D003746:Dental Enamel Proteins; D013311:Streptozocin; D011392:Proline