Effects of metoclopramide on the mouse anterior pituitary during the estrous cycle

Hyperprolactinemia modifies extracellular matrix components associated with collagen fibrillogenesis in harderian glands of non- and pregnant female mice

The harderian gland (HG) is a gland located at the base of the nictating membrane and fills the inferomedial aspect of the orbit in rodents. It is under the influence of the hypothalamic-pituitary-gonadal axis and, because of its hormone receptors, it is a target tissue for prolactin (PRL) and sex steroid hormones (estrogen and progesterone). In humans and murine, the anterior surface of the eyes is protected by a tear film synthesized by glands associated with the eye. In order to understand the endocrine changes caused by hyperprolactinemia in the glands responsible for the formation of the tear film, we used an animal model with metoclopramide-induced hyperprolactinemia (HPRL). Given the evidences that HPRL can lead to a process of cell death and tissue fibrosis, the protein expression of small leucine-rich proteoglycans (SLRPs) was analyzed through immunohistochemistry in the HG of the non- and the pregnant female mice with hyperprolactinemia. The SRLPs are related to collagen fibrillogenesis and they participate in pro-apoptotic signals. Our data revealed that high prolactin levels and changes in steroid hormones (estrogen and progesterone) can lead to an alteration in the amount of collagen, and in the structure of type I and III collagen fibers through changes in the amounts of lumican and decorin, which are responsible for collagen fibrillogenesis. This fact can lead to the impaired functioning of the HG by excessive apoptosis in the HG of the non- and the pregnant female mice with HPRL and especially in the HG of pregnancy-associated hyperprolactinemia.

Med12 regulates ovarian steroidogenesis, uterine development and maternal effects in the mammalian egg

The transcriptional factor MED12 is part of the essential mediator transcriptional complex that acts as a transcriptional coactivator in all eukaryotes. Missense gain-of-function mutations in human MED12 are associated with uterine leiomyomas, yet the role of MED12 deficiency in tumorigenesis and reproductive biology has not been fully explored. We generated a Med12 reproductive conditional knockout mouse model to evaluate its role in uterine mesenchyme, granulosa cells, and oocytes. Mice heterozygous for Med12 deficiency in granulosa cells and uterus (Med12fl/+ Amhr2-Cre) were subfertile, while mice homozygous for Med12 deficiency in granulosa cells and uterus (Med12fl/fl Amhr2-Cre) were infertile. Morphological and histological analysis of the Med12fl/fl Amhr2-Cre reproductive tract revealed atrophic uteri and hyperchromatic granulosa cells with disrupted expression of Lhcgr, Esr1, and Esr2. Med12fl/fl Amhr2-Cre mice estrous cycle was disrupted, and serum analysis showed blunted rise in estradiol in response to pregnant mare serum gonadotropin. Uterine atrophy was partially rescued by exogenous steroid supplementation with dysregulation of Notch1 and Smo expression in steroid supplemented Med12fl/fl Amhr2-Cre uteri, indicating intrinsic uterine defects. Oocyte-specific ablation of Med12 caused infertility without disrupting normal folliculogenesis and ovulation, consistent with maternal effects of Med12 in early embryo development. These results show the critical importance of Med12 in reproductive tract development and that Med12 loss of function does not cause tumorigenesis in reproductive tissues.

Effects of hyperprolactinemia on the tibial epiphyseal plate of mice treated with sex hormones

The aim of this study was to evaluate the effects of metoclopramide-induced hyperprolactinemia on the tibial epiphyseal plate of hormone-treated oophorectomized mice. For this purpose, 18 animals with intact ovaries were allocated to two groups, M (metoclopramide) and V (vehicle). One hundred and eight oophorectomized animals were allocated to 12 subgroups: Oophx/V (vehicle); Ooph/M (metoclopramide); Oophx/V + E (vehicle + estradiol); Oophx/M + E (metoclopramide + estradiol); Oophx/V + P (vehicle + progesterone); Oophx/M + P (metoclopramide + progesterone); Oophx/V + T (vehicle + testosterone); Oophx/M + T (metoclopramide + testosterone); Oophx/V + E + P (Vehicle + estradiol + progesterone); Oophx/M + E + P (metoclopramide + estradiol + progesterone); Oophx/V + E + P + T (vehicle + estradiol + progesterone + testosterone); Oophx/M + E + P + T (metoclopramide + estradiol + progesterone + testosterone). After a 50-day treatment was performed histomorphometric and immunohistochemical cell death analysis. In the epiphyseal plate of the hyperprolactinemic and/or oophorectomized animals, cell proliferation and bone formation decreased, inducing intensified cell death. In the sex steroid-treated animals, estrogen boosted cell proliferation; progesterone, bone formation and testosterone, both cell proliferation and bone formation. These findings suggest that oophorectomy and hyperprolactinemia changed epiphyseal plate morphology causing cartilage degeneration. Treatment with combined sex steroids may diminish such deleterious effects.

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

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.

The effects of joint immobilization on articular cartilage of the knee in previously exercised rats

Studies have determined the effects of joint immobilization on the articular cartilage of sedentary animals, but we are not aware of any studies reporting the effects of joint immobilization in previously trained animals. The objective of the present study was to determine whether exercise could prevent degeneration of the articular cartilage that accompanies joint immobilization. We used light microscopy to study the thickness, cell density, nuclear size, and collagen density of articular cartilage of the femoral condyle of Wistar rats subjected to aerobic physical activity on an adapted treadmill five times per week. Four groups of Wistar rats were used: a control group (C), an immobilized group (I), an exercised group (E), and an exercised and then immobilized group (EI). The right knee joints from rats in groups I and EI were immobilized at 90 °C of flexion using a plastic cast for 8 weeks. Cartilage thickness decreased significantly in group I (mean, 120.14 ± 15.6 μm, P < 0.05), but not in group EI (mean, 174 ± 2.25), and increased significantly in group E (mean, 289.49 ± 9.15) compared with group C (mean, 239.20 ± 6.25). The same results were obtained for cell density, nuclear size, and collagen density (in all cases, P < 0.05). We concluded that exercise can prevent degenerative changes in femoral articular cartilage caused by immobilization of the knee joint.