Microscopical and biochemical analyses of salivary glands in alendronate-treated rats

Objectives: Bisphosphonates are antiresorptive drugs largely prescribed for patients in a wide range of ages. However, little is known about their possible side-effects in other regions of the body. The objective of this study was to evaluate the effects of sodium alendronate on salivary glands of young rats treated with this bisphosphonate by morphological and biochemical analyses. Methods: Newborn rats were treated with doses of 2.5mg/kg/day of sodium alendronate during 30 days; control specimens were treated with sterile saline. On the thirtieth day, the parotid and submandibular glands were collected, and some glands were fixed for histology, in 0.1% glutaraldehyde + 4% formaldehyde, under microwave irradiation. Then, they were dehydrated in ethanol and embedded in JB-4 historesin. The sections were stained and examined in a light microscope. Other salivary glands were collected, homogenized, centrifuged and the supernatant was used for biochemical analyses of protein content and amylase activity. The protein concentration was measured and read in spectrophotometer by using Folin's phenol reagent and the bovine serum albumin as standard. The amylase activity was measured after incubation with potassium phosphate buffer, for 5 minutes at 30 Celsius degrees. The reaction was stopped by adding alkaline solution and then maintained in boiling water for 5 minutes. The mixture was diluted with water and the intensity of the developed color was measured in spectrophotometer using maltose as standard. Results: At light microscopy, parotid and submandibular glands from the alendronate-treated animals presented numerous secretion granules in the secretory cells when compared with the control specimens. Biochemical analyses revealed an increase in total protein content in both glands from the alendronate-treated animals compared with the control ones; contrarily, amylase levels decreased in the treated samples. Conclusion: Alendronate treatment interferes on the secretory pathways of both parotid and submandibular glands in young rats.