Influence of hyperprolactinemia on collagen fibers in the lacrimal gland of female mice

Abstract

OBJECTIVE:To quantify the collagen fibers in the lacrimal gland of female mice with hyperprolactinemia.METHODS:Forty adult female mice were randomly divided into two groups with 20 animals each: nonpregnant control (CTR1, control group, 0.2 mL of saline solution) and nonpregnant experimental (HPRL1, experimental group, 200 µg/day metoclopramide). Treatments lasted for 50 consecutive days. On day 50, 10 females from each group (control and experimental) were euthanized in the proestrus phase; then, the blood was collected and the lacrimal glands were removed. Thereafter, the remaining females were placed with the mates and continued to receive treatment with saline solution or metoclopramide. On the 6th post-coital day, 10 pregnant females from the control group (CTR2) and 10 pregnant females from the experimental group (HPRL2) were euthanized, after which blood was collected and the lacrimal glands removed. The lacrimal glands were processed for morphological analyses and collagen quantification, and prolactin and sex steroid levels were measured in the blood samples. Data were statistically analyzed using an unpaired Student t test (p<0.05).RESULTS:Morphological analysis revealed greater structural tissue disorganization of the lacrimal glands in the metoclopramide-treated groups. The total collagen content was significantly higher in the HPRL1 group than in the CTR1 group (p<0.05), whereas the difference between the CTR2 and HPRL2 groups was not significant.CONCLUSION:Our data suggest an impairment in the functioning of the lacrimal gland as a consequence of increased prolactin levels and decreased serum levels of estrogen and progesterone.

Imbalance between the cellular proliferation and death in harderian gland of female mice with hyperprolactinemia

“…Araujo et al 5 , in agreement with previous studies that used the same HPrl model 10,11 , showed that serum PRL levels increased and that serum progesterone and estrogen levels decreased in all animals with HPrl when compared to control ones. Those findings suggest an impairment in LG function caused by increased serum PRL levels and decreased estrogen and progesterone.…”

“…PRL and ovarian hormones (estrogen and progesterone) have been investigated in the animal model (female) so as to provide data for researches with metoclopramide-induced hyperprolactinemia (HPrl). Histological study showed signs of a decreased intra-orbital LG cells activity due to changes in the cell volume of the acinar cells, as well as an increased number of collagen fibers in the connective tissue that supports the LG of female mice with HPrl 5,10 . Those studies are evidence that hyperprolactinemia could lead to processes of cell death or cell proliferation, as well as tissue fibrosis in LG and HG.…”

“…However, in murine, there is a third type of eye gland in the orbinal portion (intra-orbinal), the harderian glands (some authors consider HG to be a type of LG while others believe it to be an accessory gland in the LG). HG are found on vertebrates that have a nictitating membrane (translucent inner eyelid) [4][5][6]14 .…”

“…A total of 20 virgin female adult mice, aged 3 months old, Mus musculus, and weighing 35-40g were given food and water ad libitum at room temperature (22°C) under artificial light with a 12:12 hour light:dark photoperiod (lights on from 7 a.m.-7 p.m.). Thereafter, they were adapted to the new environment for 2 weeks, vaginal smears were collected daily and stained by Harris-Shorr for cytological analysis for evidence of regular estrous cycles 5 . Initially, induction of HPrl was performed, 10 females received subcutaneous injections of 200 μg/day of metoclopramide dissolved in 0.2 mL of saline solution for 50 consecutive days (hyperprolactinemic group, HPrl), and 10 females received subcutaneous injections of 0.2 mL of saline solution for 50 consecutive days (control group, Ctr).…”

“…Hyperprolactinemia is the most common disorder of the hypothalamic-pituitary-gonadal axis 1 and may have physiological causes -pregnancy, nursing, sleep, stress, sexual dysfunctions, or even a pathological cause -a tumor called prolactinoma. Hyperprolactinemia is a condition similar to hypogonadism, since it acts negatively on ovarian function [2][3][4][5] . However, the relationship between hyperprolactinemia and the function of the lacrimal (LG) or the harderian glands (HG) is not well defined.…”