Ovariectomy reduces the gelatinolytic activity and expression of matrix metalloproteinases and collagen in rat molar extraction wounds

A New Experimental Technique for Complete Extraction of Mandibular First Molar Teeth in Rats

Intact extraction of the mandibular first molar tooth is an interesting model for studies of alveolar bone healing. The aim of this study was to describe a new experimental technique for extraction of rat mandibular first molar teeth with crown and all 4 roots intact using controlled forces applied to the teeth. One hundred and twenty female Sprague-Dawley rats were used from a center for experimental animal research. Animals underwent general anesthesia and were then placed in a special dental unit (designed by Moghadam) for the extraction of rat teeth. After syndesmotomy, luxation of the tooth began with a tipping movement in the buccal direction with a very low range of motion for 1 s. A tipping movement in the lingual direction was then used to continue luxation. After a maximum of 10 repetitions, the tooth was left alone for 30 s. After 3-4 stages of this cycle, the tooth loosened. To complete the luxation, the same forces were applied in the buccal and lingual directions with larger amplitude for 3 s. After this step, the tooth was loose enough to be easily extracted. The alveolus was then sutured closed. The results showed no hemorrhage or fracture of crowns and mesial or distal roots, and only 8% of the buccal and lingual roots fractured. The technique designed and used in this study was shown to be an effective model for complete molar tooth extraction in the rat. This technique could also be used in the treatment of other rodents.

Effects of osteoporosis on alveolar bone repair after tooth extraction: A systematic review of preclinical studies

OBJECTIVE

This systematic review aimed to address whether the alveolar socket repair after a tooth extraction is impacted by an osteoporotic phenotype and propose methodological observations.

DESIGN

A search strategy in MEDLINE/PubMed, EMBASE, Web of Science, and Scopus databases was performed. Quality assessment was carried out through the SYRCLE Risk of Bias tool.

RESULTS

Out of the 1147 potentially relevant records, 25 met the inclusion criteria. Most of the studies were performed in rats, and ovariectomy (OVX) was the most frequent osteoporosis induction method. Histomorphometry, micro-computed tomography (microCT), and immunohistochemistry were the main bone repair evaluation methods. Most of the included studies (88 %) presented negative impacts of osteoporosis on the alveolar socket repair. Only three studies (12 %) showed no statistical differences among groups. Overall, most of the quality assessment categories presented a high percentage of unclear risk of bias due to insufficient information in the studies.

CONCLUSIONS

The results indicated that an osteoporotic phenotype seems to impair alveolar socket repair after tooth extraction. However, there is still a lack of information and standardization. Therefore, further studies should consider the proposed methodological aspects regarding animal characteristics, OVX associated with a low calcium diet, waiting 8 weeks to osteoporosis induction, maxillary molars as the best option for tooth extraction, confirming and reporting OVX and osteoporosis success, and an appropriate method of repair analysis.

Systemic Lithium Chloride Administration Improves Tooth Extraction Wound Healing in Estrogen-Deficient Rats

The purpose of this investigation was to evaluate the effects of lithium chloride (LiCl) on the socket healing of estrogen-deficient rats. Seventy-two rats were allocated into one of the following groups: Control, Ovariectomy and LiCl (150 mg/kg/2 every other day orally) + Ovariectomy. Animals received LiCl or water from the 14th day post-ovariectomy, until the completion of the experiment. On the 21st day after ovariectomy, the first molars were extracted. Rats were euthanized on the 10th, 20th and 30th days following extractions. Bone healing (BH), TRAP positive cells and immunohistochemical staining for OPG, RANKL, BSP, OPN and OCN were evaluated. The Ovariectomy group presented decreased BH compared to the LiCl group at 10 days, and the lowest BH at 20 days (p<0.05). At 30 days, the Ovariectomy and LiCl-groups presented lower BH than that of the Control (p<0.05). The number of TRAP-stained cells was the lowest in the LiCl group at 20 days and the highest in the Ovariectomy group at 30 days (p<0.05). At 10 days of healing, the LiCl group demonstrated stronger staining for all bone markers when compared to the other groups, while the Ovariectomy group presented higher RANKL expression than that of the Control (p<0.05). LiCl enhanced bone healing in rats with estrogen deficiency, particularly in the initial healing phases. However, as data on the effects of lithium chloride on bone tissue are still preliminary, more studies related to its toxicity and protocol of administration are necessary before its application in clinical practice.

Presence of mast cells and the expression of metalloproteinase 9 in the gingiva of ovariectomized rats with periodontal disease

Background

The host's answer has an important role in periodontal disease, and the mast cells have a prime role. Such cells seem to be influenced by estrogen deficiency. The objective was to evaluate the mast cells and the expression of metalloproteinase(MMP)-9 in periodontal disease induced in ovariectomized rats.

Methods

For that purpose, 36 rats were used; 18 ovariectomized (OVX) and another 18 Sham-operated (SHAM). After 60 days the periodontal disease was induced by a ligature around the first lower right molars (group P). The opposite side was the control group (group C). The euthanasia occurred 3, 7 and 14 days after the placement of the ligature. The gingiva was removed and analyzed histochemically and immunohistochemically to quantify the mast cells and to analyze MMP 9 expression.

Results

By comparing the groups SHAM-P and C and groups OVX-C and P, it was noted that mast cells from group C were higher than P in all experimental periods. When comparing groups SHAM-C and OVX-C, significant factors were not found. When comparing groups SHAM-P and OVX-P, there was an inclination for mast cells reduction with time. The MMP-9 expression was related to the presence of periodontitis.

Conclusions

It was concluded that periodontitis led to mast cells reduction and MMP-9 increase. The ovariectomy itself did not alter the MMP-9 expression and did not influence the presence of mast cells in rat papilla, however, when associated to inflammation led to a reduction of mast cells.

Delayed wound healing after tooth extraction and self-reported kyphosis in Japanese men and women

It is unclear whether osteoporosis itself is a main risk factor for delayed wound healing after tooth extraction in humans. In this study, we evaluated the association between experience of delayed wound healing after last tooth extraction and self-reported kyphosis, with the possibility of having vertebral fractures, in Japanese patients. Among the 1,504 patients who responded to the structured questionnaire survey, 518 patients (134 men and 384 women) aged 55-97 years finally participated in this study. Patients who self-reported mild-moderate kyphosis were more likely to have problematic delayed wound healing after last tooth extraction than those who reported severe kyphosis (odds ratio [OR] 4.98; 95% confidence interval [CI], 1.86-13.38 and OR 2.30; 95% CI, 0.52-10.22, respectively) (p for trend = 0.005). Japanese patients with vertebral fractures may have a higher risk of having problematic delayed wound healing after tooth extraction.

Effects of experimental osteoporosis and low calcium intake on postextraction sockets of rats

This study analysed the initial effects of the combination of oestrogen deficiency with a calcium-deficient diet on alveolar bone repair. Sixty-three 3-month-old female rats were either ovariectomized (OVX, n = 42) or sham-operated (SHAM, n = 21). Among the 42 ovariectomized rats, 21 received standard commercial food (OVX) and 21 received food with low calcium content (ESP). The mandibular first molars were extracted bilaterally 15 days after ovariectomy or sham surgery. The rats were weighed and killed at 7, 21 and 45 days after tooth extraction. The results were evaluated by descriptive microscopic analysis, histomorphometry of the trabecular and osteoid volume and mast cell counts. Analysis of the results indicated that trabecular volume and mast cell counts increased significantly over time, while osteoid volume decreased over time. Comparisons between the SHAM and OVX groups demonstrated no statistical differences, while comparison between the OVX and ESP groups indicated differences in trabecular volume and the number of mast cells. The data suggest that hormonal deficiency does not delay alveolar bone repair in OVX rats; however, oestrogen deficiency associated with calcium deficiency can lead to bone resorption through the activation of mast cells.

Effects of diosgenin on myometrial matrix metalloproteinase-2 and -9 activity and expression in ovariectomized rats

Diosgenin, a traditional Yam extraction, has been used in hormone replacement for menopausal women. We aimed to investigate the influences of diosgenin administration upon the MMP-2 and -9 activity and expression and reproductive hormones of ovariectomized (OVX) rats, a model of menopausal status. Seven-week old female Wistar rats with bilateral OVX or sham operation (controls) were divided and administered different dosages of diosgenin (0, 10, 50, or 100 mg/kg/day) for 8 weeks. Serum was then sampled for progesterone (P4) and estradiol (E2) assay and uterine horns harvested. Myometrial MMP-2 and -9 activity and expression were surveyed and myometrial collagen expression was also assayed. The results show higher body weight in OVX rats across the 8 weeks post surgery and no significant differences were noted among OVX or Sham rats with diosgenin supplements. There were lower P4 and E2 concentrations in OVX rats compared to Sham rats, and higher P4 concentration of Sham rats post diosgenin supplement. MMP-2 and -9 mRNA expression and activity was lower in OVX rats, although higher MMP-2 and lower MMP-9 activity/mRNA expression was observed in OVX rats post diosgenin supplementation. Collagen mRNA expression was higher in OVX rats compared to Sham controls, and diosgenin administration decreased collagen mRNA expression in OVX rats. In conclusion, diosgenin is associated with gelatinase expression and collagen metabolism in OVX rats. Diosgenin administration can partially reverse the effects of OVX upon MMP functions and hormone status. Adequate diosgenin supplement might modulate myometrial gelatinase expression and collagen metabolism in menopausal subjects.

Effects of resistance training on matrix metalloproteinase-2 activity and biomechanical and physical properties of bone in ovariectomized and intact rats

The purpose of this study was to investigate the influence of resistance training on the activity of matrix metalloproteinase (MMP)-2 and bone biomechanical properties in ovariectomized and intact rats. Forty-eight female rats were divided into two distinct groups, ovariectomized (OVX) and intact (Int), which were subdivided into three similar subgroups: sedentary, acute exercise and chronic exercise. Rats performed a resistance training for 12 weeks in which animals climbed a vertical ladder of 1.1 m with weights attached to their tails. Sessions were performed with an interval of 3, 4-9 and 8-12 days scaled dynamic movements of climbing. Biomechanical and physical analyses were performed using a universal testing machine, and MMP-2 activity analysis by zymography. Bone density (BD), mineral density (MD), maximum load and fracture load was reduced in sedentary and acute exercise OVX groups compared with the sedentary intact group (P<0.05); in contrast, chronically trained groups (OVX and Int) showed a significant increase in BD, MD and fracture load compared with all the other groups. MMP-2 activity in chronically trained groups also showed a significant increase, while the sedentary OVX group showed a decrease in MMP-2 activity compared with the intact sedentary group (P<0.05). Our results suggest that the resistance training proposed in our work was efficient in reverting the deleterious effects of ovariectomy on bone tissue, and also produced modeling effects in intact rats. On the other hand, ovariectomy reduced the activity of MMP-2 and produced deleterious effects on bone tissue, mimicking menopause intrinsically.

Sex, collagen expression, and anterior cruciate ligament strength in rats

CONTEXT

Sex-specific responses to steroid sex hormones have been suggested as a potential cause for the disparate anterior cruciate ligament (ACL) injury rates between male and female athletes. Type 1 collagen (T1C) and type 3 collagen (T3C) are crucial structural components that define the ligament's ability to withstand tensile loads. Messenger RNA (mRNA) is an important mediator of downstream collagen synthesis and remodeling, but the sex-specific mechanisms of collagen mRNA expression and ACL strength are unknown.

OBJECTIVE

To examine the influence of sex on T1C and T3C mRNA expression and mass-normalized stiffness and peak failure load in the ACLs of skeletally mature rats.

DESIGN

Observational study.

SETTING

Basic sciences and biomechanical testing laboratories.

PATIENTS OR OTHER PARTICIPANTS

Nineteen 12-week-old male (n = 9) and female (n = 10) Sprague Dawley rats.

MAIN OUTCOME MEASURE(S)

We used real-time polymerase chain reaction to determine T1C and T3C mRNA expression and a hydraulic materials testing device to measure ACL stiffness and failure load. Nonparametric Wilcoxon rank sum tests were used to compare the groups.

RESULTS

Female rats had lower amounts of T3C mRNA expression and higher normalized ACL tangent stiffness and failure load than male rats.

CONCLUSIONS

These findings suggest that sex-specific differences in T1C and T3C mRNA expression may play an important role in the downstream mechanical properties of the ACL.

In vivo effects of zoledronic acid on oral mucosal epithelial cells

OBJECTIVE

Osteonecrosis of the jaw is a serious complication of bisphosphonate treatment for which the pathophysiology is unknown. The purpose of this study was to investigate whether in vivo zoledronic acid (ZA) induces alterations in cell proliferation, apoptosis, and matrix metalloproteinases (MMPs) expression in oral mucosal epithelial cells.

METHODS

One-year-old dogs were either untreated (control group) or given high doses of intravenous ZA (ZA group) for 3 months. The doses of ZA were equivalent to those given to cancer patients, yet were administered two times more frequently (every 2 weeks). Mucosal tissues were assessed immunohistochemically for cell proliferation (proliferating cell nuclear antigen, PCNA), matrix metalloproteinase (MMP) expression, and apoptosis (caspase 3 and TUNEL).

RESULTS

There were no significant differences between the groups with respect to PCNA, MMP-2, MMP-14, and TUNEL positive cells. However, the expression of MMP-9 was significantly higher in the control group than in the ZA group (P < 0.05), whereas the expression of caspase 3 was significantly lower in the control group than in the ZA group (P < 0.05).

CONCLUSION

  These results suggest that high doses of ZA resulted in higher levels of apoptosis and lower levels of MMP-9 in the oral epithelial cells supporting the idea of bisphosphonate treatment affects the oral mucosa.

Expression of estrogen, androgen, and glucocorticoid receptors in recent striae distensae

BACKGROUND

Stretch marks or striae distensae (SD) can be considered a common skin disorder, but their physiopathogenic mechanisms have not been totally clarified. Although it is considered an esthetic complaint, it may have serious psychosocial consequences besides the local and systemic alterations of the conjunctive tissue. This study aims at assessing and quantifying the estrogen, androgen and glucocorticoid receptors in skin samples with striae and comparing with normal skin.

METHODS

Skin samples for biopsy were obtained from eight patients with SD and eight patients without lesions. The samples were frozen at -80 degrees C and underwent processing to obtain proteic extract to quantify the estrogen, androgen and glucocorticoid receptors with the Western Blot method.

RESULTS

When the estrogen receptor in the skin with SD was compared with healthy skin, it was observed to have increased twice as much (P = 0.00001). The androgen and glucocorticoid receptors in the SD skin had also increased (P = 0.00015 and P = 0.00083, respectively).

CONCLUSIONS

These findings indicate that under certain conditions there is an increase in hormonal receptor expression, suggesting that regions that undergo greater mechanical stretching of the skin may express greater hormonal receptor activity. This activity may influence the metabolism of the extracellular matrix, causing the formation of SD. Alterations in hormone receptors occur within a well-defined time period during the formation of SD; however, there are differences in the functionality of hormone receptors during different stages in the development of the lesions. The preliminary results appear to be relevant and represent an initial step towards an understanding of the pathophysiology of SD.

Osteocalcin immunolabeling during the alveolar healing process in ovariectomized rats treated with estrogen or raloxifene

The influence of an estrogen-deficient state was evaluated in this study and also its treatments with estrogen (E(2)) or with raloxifene (RLX) on the expression of osteocalcin during the periods of the chronology of the alveolar bone healing process (7, 14, 21, 28 and 42 post-extraction days) by means of immunohistochemistry reactions and histomorphometric analysis. Rats (200-220 g) with oestrus cycles normal were either OVX or sham-operated and divided into four groups: sham, OVX control (OVX/O), estrogen (OVX/E(2); 17 beta-estradiol, 400 microg/mo) and raloxifene (OVX/RLX; 1 mg/kg bw/d) groups. Histomorphometric analysis showed the sham group presented the highest mean value of bone formation post-extraction. The reaction of immunohistochemistry for osteocalcin presented stronger expression of osteocalcin with predominance at 14 and 21 days on sham group. The OVX/RLX group presented better results than OVX/E(2), considering the expression of osteocalcin in osteoblastic lineage cells, but still inferior than the sham group. It was concluded that ovariectomy decreases the mineralization process and the osteocalcin expression during the chronology of the alveolar healing process that is not totally recovered with estrogen replacement or raloxifene treatment.

Ovariectomy delays alveolar wound healing after molar extractions in rats

PURPOSE

This study was conducted to investigate the morphological effects of the absence of estrogen on alveolar wound healing of young female rats after tooth extraction.

MATERIALS AND METHODS

A total of 60 4- to 6-week-old female rats underwent bilateral ovariectomy (OVX) or sham operations. Three weeks later, the first mandibular molars were extracted. Subsequently, the animals were killed by cervical dislocation 3, 5, 7, 14, 21, or 28 days after tooth extraction. The mandibles were removed, and serial transversal sections of mesial alveolus of the first mandibular molars were obtained for histometric analysis.

RESULTS

OVX sockets showed significant increases in fibroblasts and collagen content 3 and 5 days after the extractions, followed by significant decreases in these parameters in the subsequent periods. In accordance with the decreased collagen content in the latest period of healing, new bone formation was significantly reduced in the OVX animals.

CONCLUSION

These findings suggest that the initial molecular changes observed in the absence of estrogen lead to delayed alveolar wound healing.

High Bcl-2/Bax ratio in Walker tumor cells protects mitochondria but does not prevent H2O2-induced apoptosis via calcineurin pathways

It has been previously shown that Walker 256 tumor cells express a high content of the anti-apoptotic protein Bcl-2 which protects mitochondria against the damaging effects of Ca(2+). In the present study, we analyze H(2)O(2)-induced apoptotic death in two different types of tumor cells: Walker 256 and SCC-25. Treatment with H(2)O(2) (4mM) increased reactive oxygen species generation and the concentration of cytosolic free Ca(2+). These alterations preceded apoptosis in both cell lines. In Walker cells, which show a high Bcl-2/Bax ratio, apoptosis was dependent on calcineurin activation and independent of changes in mitochondrial membrane potential (DeltaPsi(m)), as well as cytochrome c release. In contrast, in SCC-25 cells, which show a lower Bcl-2/Bax ratio, apoptosis was preceded by a decrease in DeltaPsi(m), mitochondrial permeability transition, and cytochrome c release. Caspase-3 activation occurred in both cell lines. The data suggest that although the high Bcl-2/Bax ratio protected the mitochondria of Walker cells from oxidative stress, it was not sufficient to prevent apoptosis through calcineurin pathways.

Evaluation of different rotary devices on bone repair in rabbits

In oral surgery, the quality of bone repair may be influenced by several factors that can increase the morbidity of the procedure. The type of equipment used for ostectomy can directly affect bone healing. The aim of this study was to evaluate bone repair of mandible bone defects prepared in rabbits using three different rotary devices. Fifteen New Zealand rabbits were randomly assigned to 3 groups (n=5) according to type of rotary device used to create bone defects: I - pneumatic low-speed rotation engine, II - pneumatic high-speed rotation engine, and III - electric low-speed rotation engine. The anatomic pieces were surgically obtained after 2, 7 and 30 days and submitted to histological and morphometric analysis. The morphometric results were expressed as the total area of bone remodeling matrix using an image analysis system. Increases in the bone remodeling matrix were noticed with time along the course of the experiment. No statistically significant differences (p>0.05) were observed among the groups at the three sacrificing time points considering the total area of bone mineralized matrix, although the histological analysis showed a slightly advanced bone repair in group III compared to the other two groups. The findings of the present study suggest that the type of rotary device used in oral and maxillofacial surgery does not interfere with the bone repair process.

Verapamil-sensitive Ca2+ channel regulation of Th1-type proliferation of splenic lymphocytes induced by Walker 256 tumor development in rats

Recently, we demonstrated that verapamil, an L-type Ca2+ channel blocker, inhibits the activation of splenic lymphocytes during Walker 256 ascitic tumor development in adult rats. In the present study we have analyzed the changes in spleen size, splenic lymphocyte proliferation, white pulp organization and relative size as well as food intake, and levels of blood haemoglobin in Walker 256 tumor bearing rats. These rats displayed a spleen enlargement associated with a significant increase in white pulp area and TCD8+ lymphocyte proliferation. Levels of interferon-gamma, but not of interleukin-10, were elevated in tumor bearing rats, indicating a Th1-type immune response. These manifestations were accompanied by reduced food intake and anaemia. Treatment of tumor bearing rats with verapamil avoided spleen enlargement and increased expression of cytokines, as well as the splenic TCD8+ lymphocyte proliferation. In addition, verapamil treatment promoted an exacerbation of the anorexia and anaemia caused by Walker tumor development. No such effect was observed in control rats treated with verapamil. Taken together, these findings suggest that verapamil inhibits the immune response to cancer, resulting in an increase of the systemic effects induced by Walker 256 tumor.

Hernia fibroblasts lack beta-estradiol-induced alterations of collagen gene expression

BACKGROUND

Estrogens are reported to increase type I and type III collagen deposition and to regulate Metalloproteinase 2 (MMP-2) expression. These proteins are reported to be dysregulated in incisional hernia formation resulting in a significantly decreased type I to III ratio. We aimed to evaluate the beta-estradiol mediated regulation of type I and type III collagen genes as well as MMP-2 gene expression in fibroblasts derived from patients with or without history of recurrent incisional hernia disease. We compared primary fibroblast cultures from male/female subjects without/without incisional hernia disease.

RESULTS

Incisional hernia fibroblasts (IHFs) revealed a decreased type I/III collagen mRNA ratio. Whereas fibroblasts from healthy female donors responded to beta-estradiol, type I and type III gene transcription is not affected in fibroblasts from males or affected females. Furthermore beta-estradiol had no influence on the impaired type I to III collagen ratio in fibroblasts from recurrent hernia patients.

CONCLUSION

Our results suggest that beta-estradiol does not restore the imbaired balance of type I/III collagen in incisional hernia fibroblasts. Furthermore, the individual was identified as an independent factor for the beta-estradiol induced alterations of collagen gene expression. The observation of gender specific beta-estradiol-dependent changes of collagen gene expression in vitro is of significance for future studies of cellular response.