Recovery of INS-R and ER-alpha expression in the salivary glands of diabetic mice submitted to hormone replacement therapy

Abstract

The interaction between proteins and cell receptors is related to tissue homeostasis such as in salivary glands. In this respect, alterations in hormone levels caused by hyperglycaemic conditions may interfere with this interaction, intensifying the damage caused by diabetes mellitus. Hormone replacement therapy is an option to reverse this damage, but doubts still exist regarding the efficacy of this procedure. The objective of this study was to evaluate the effect of oestrogen replacement therapy combined with insulin treatment on the expression of oestrogen (ER-alpha) and insulin receptors (INS-R) in the salivary glands of spontaneously diabetic mice. Twenty-five mice were divided into five group of 5 animals each: group I (NOD diabetic), group II (NOD diabetic treated with insulin), group III (NOD diabetic treated with oestrogen), group IV (NOD diabetic treated with insulin and oestrogen), and group V (control BALB/c mice). Group II received insulin, group III received oestrogen, and group IV received insulin plus oestrogen administered daily for 20 days. Groups I and V received saline for the same period of time to simulate treatment. Glucose and oestrogen levels were monitored during the experimental period and salivary gland samples were collected at the end of the experiment for fluorescence microscopy analysis of ER-alpha and INS-R. Animals receiving oestrogen replacement therapy plus insulin showed regulation of the expression of oestrogen and insulin receptors. Oestrogen treatment alone contributed to the recovery of these cell receptors. These results indicate that oestrogen replacement therapy alone, and especially when combined with insulin, is important for the recovery of the interaction between functional proteins and their receptors, thus contributing to the reestablishment of tissues damaged by the hyperglycaemic condition.