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Revista chilena de anatomía

versión impresa ISSN 0716-9868

Rev. chil. anat. v.15 n.1 Temuco  1997

http://dx.doi.org/10.4067/S0716-98681997000100014 

MORPHOLOGICAL ASPECTS OF THE LAMINA PROPRIA OF GINGIVA
OF PERSISTENT OESTROUS RATS, OR SUBMITTED TO OOPHORECTOMY AND
TREATED WITH ESTROGEN OR DEXAMETHASONE

 

ASPECTOS MORFOLOGICOS DE LA LAMINA PROPIA DE LA GINGIVA DE
RATAS EN ESTRO PERMANENTE, OOFORECTOMIZADAS Y TRATADAS CON
ESTROGENO O DEXAMETASONA.

 

Calió, P. L.
Simões, M. J.
Mora, O. A.
Evêncio-Neto, J.

Department of Morphology UNIFESP-EPM, Brazil.

 

SUMMARY: The authors performed an ultrastructural investigation in order to study whether the estrogen would be able to modify the answer of the gingival stroma of rats.

The results showed that the lamina propria of the gingiva of animals in permanent oestrous and oophorectomy treated with estrogens was rich in cells with predominance of collagen fibers. It was also observed a great number of eosinophils and active fibroblasts, few macrophages and lymphocytes. Some electrontranslucent spaces were observed in the stroma. In group of oophorectomyzed, the cellular stroma showed a great amount of amorphous and fibrilar ground substance, atrophic fibroblasts, some macrophages and few leukocytes showing degenerative features. The gingival stroma was atrophic in the group treated with dexamethasone, showing a great number of cells and collagen fibers as wells as fibroblasts and fibrocytes. Reduced number of macrophages, plasmocytes and leukocytes was observed.

It was possible to conclude that the gingival stroma of rats should be considered a target organ of estrogen and that oophorectomy does not modify this feature.

KEY WORDS: 1. Gingiva; 2. Electron microscopy; 3. Estrogen; 4. Dexamethasone.

INTRODUCTION

Some observations are frequent on daily activity of odontological clinic, mainly with regard to modifications in women’s oral mucosa during menstrual cycle and pregnancy.

However, the experimental literature has been controversial on the possibility of hormonal flutuations interfering directly in the components of lamina propria of oral mucosa. ZISKIN et al. (1943), NUTLEY et al. (1954) and PHILIPPI (1974) mention that gingiva respond to hormonal stimuli. Nevertheless, LITWACK et al. (1970), HUGOSON et al. (1972) and PARK (1982) did not observe any difference.

Little is known about the behavior of the lamina propria of gingiva in hormonal states of chronic anovulation in which the lamina propria of gingiva is under continuous stimulation by estrogen. In the present study we observed the ultrastructural aspects of lamina propria of persistent oestrous rats’ gingivae treated with estrogen and dexamethasone, in order to confirm whether the gingiva is a target organ of sexual hormones.

MATERIAL AND METHOD

We utilized 25 adult virgin female rats (Rattus norvegicus albinus) in state of persistent oestrous obtained by subcutaneous injection of 1.50 mg of testosterone propionate on the second day of life (SMANIOTTO, 1966). Persistent oestrous was confirmed by serial hormonal colpocytology performed at 90 days of life for two weeks. After this period the animals were divided in five groups of five rats each: (a) Group I (GI) rats who did not receive any hormonal treatment (control group), (b) Group II (GII) rats submitted to bilateral oophorectomy (control group), (c) Group III (GIII) rats submitted to bilateral oophorectomy and receiving 10 (g/day of 17 ( estradiol-3-benzoate (s.c), (d) Group IV (GIV) rats in persistent oestrous receiving 0.8 mg/day of dexamethasone (s.c), and Group V (GV) rats submitted to bilateral oophorectomy receiving only the soy oil and benzilic alcohol (s.c). Hormones were administered after the 21st day of bilateral oophorectomy during five consecutive days in the amount of 1 ml subcutaneous (s.c). Fragments of the gingivae of the lingual aspect of the inferior molar teeth were fixed by immersion in 2.5% glutaradehyde in 0.1 mol/l phosphate buffer (pH = 7.3), for 3h at cold (4 (C), with postfixation, at same conditions, in 1% phosphate buffered OsO4 (0.1 mol/l, pH = 7.3). The tissues were washed in the buffer, dehydrated and finally embedded in araldite. Ultrathin sections (60 to 80nm) were stained with uranyl acetate and lead citrate, and examined in a Zeiss EM-900 TEM.

RESULTS

All groups presented lamina propria with similar features to the ones presented in connective tissue of other organs, in other words, various types of cells (fibroblasts, macrophages and leukocytes) and intercellular substance. The more frequent cells were the fibroblasts.

Control group (GI): The lamina propria presents many cells and intercellular substances with predominance of collagen fibers, which are arranged in various orientations. The fibroblasts are well developed, elongated and present various projections, a voluminous and euchromatic nucleus. In the cytoplasm, we can identify mitochondrias, rough and smooth endoplasmic reticulum (rER and sER respectively) and Golgi complex.

We can also observe high concentration of eosinophils, which present numerous granules with crystalloid bars inside. The matrix around the eosinophils shows electrotranslucent areas (Fig. 1).

GII (oophorectomy) and GV (oophorectomy and receiving only oil): The lamina propria is homogeneous, rich in cells and ground substance with predominance of collagen fibers. The fibroblasts are grouped, atrophic and show few processes, with a small, heterochromatic nucleus. Few organelles were observed in the cytoplasm of fibroblasts: mithochondrias, rER and sER. We observed also typical macrophages but no eosinophils. The collagen fibers were scattered throughout eletrotranslucent areas (Fig. 2).

GIII (oophorectomy and receiving estradiol): The numerous cells and the great amount of ground substance were conspicuous. Numerous eosinophils show in the cytoplasm ellipse granules of variable electrodensities. The well developed and elongated fibroblasts show numerous processes with a voluminous and euchromatic nucleus. The mitochondria, the rER and sER as well as the Golgi complex are conspicuous (Fig. 3).

Group IV (oophorectomy and receiving dexamethasone): numerous cells and ground substance with fibers oriented in several spatial directions are observed in the lamina propria. The fibroblasts are well developed and shows numerous processes as well as a voluminous euchromatic nucleus. The mithochondrias, sER, rER and Golgi complex are conspicuous. No eosinophils were found (Fig. 4).

DISCUSSION

In the present investigation we used the persistent oestrous rats as an experimental model mimicking chronic anovulation in order to study the effect of estrogen on the lamina propria of gingivae under constant stimulation of estrogen without the opposite effect of progesterone. The dexamethasone was used in order to antagonize the estrogen action. The dexamethasone and estrogen doses used were equivalent to those administered to humans (PATRIARCA et al., 1986).

The examination of the gingivae showed that the oophorectomy leads to atrophy of fibroblasts, reduction of eosinophils and density of collagen fibers when compared to a control groups (permanent oestrous), indicating that the gingiva is influenced by ovary hormones.

It must be mentioned that HUGOSON & LINDHE (1971a, b) and LUNDGREN et al. (1973) did not observe any histological alterations in the gingival tissue or in the degree of mononuclear cell infiltration of gingival mucosa of rats initially oophorectomyzed and then submitted to action of benzoate of estradiol. However in our experiment we could notice that estradiol induces alterations of gingival lamina propria, such as increase in activity of fibroblasts, number of eosinophils and intercellular substance. These findings were referred by PHILLIPI (1979) and MORA et al. (1983). They mention that the gingiva is a target-organ of ovarian hormones.

Fig. 1- Electromicrography of the gingival lamina propria of a rat in persistent estrous showing
fibroblasts (F) and eosinophils (E). 14 000 X.
Fig. 2- Electromicrography of the gingival lamina propria of an oophorectomized rat showing cells
grouped with few cytoplasm and heterochromatic nucleus. 7 500X.
Fig. 3- Electromicrography of the gingival lamina propria of a rat treated with estrogen showing a
great amount of ground substance, eosinophils (arrow) and portion of fibroblast ( ). 9 000 X.
Fig. 4- Electromicrography of the gingival lamina propria of a rat treated with dexamethasone
showing ground substance with collagen fibers oriented in several directions, fibroblast (F) and
macrophage (M). 11 300 X.

In permanent oestrous animals treated with dexamethasone,we notice a certain similarity, in the morphology of stroma, to the oophorectomized group, that means absence of eosinophils and some fibroblasts with cytoplasmic features of little activity. This data indicates that dexamethasone probably antagonized the estrogenic action in this group of animals in relation to the morphology of gingival stroma. These findings are supported by the works of SZEGO & DAVIS (1969), MARKAVERICK et al. (1981), BIGSBY & CUNHA (1988) and HOWE et al. (1990). According to them, glycocorticoides inhibited the growing of the rats’ uterus induced by estrogen, because they antagonized the synthesis of estrogen receptors on the endometrial stroma.

With regard to the collagen fibers, we verified higher concentrations in the oophorectomized animals and in the ones treated with dexamethasone when compared to the control group (persistent oestrous) and the group treated with estrogen, such fact must be probably caused by reduced concentration of intercellular substance, as described by SIMÕES & MORA (1980) in the rats’endometrium.

Another curious fact was the disappearance of eosinophils from the gingiva stroma of oophorectomized animals and the ones treated with dexamethasone, also showing the antiestrogenic effect of this substance since the increase in the number of eosinophils in the uterine stroma of rats is directly correlated with increasing estrogen concentrations (BJERSING & BORGLIN, 1964; PARDI et al., 1993; SMANIOTTO, 1996).

Thus, the present study showed that the lamina propria of gingiva is a target-organ of sexual hormones in albino female rats, and that new studies must be done in order to contribute to a better understanding of the human gingival pathology.

RESUMEN: Los autores realizaron un estudio ultraestructural de la gingiva de ratas en estro permanente, ooforectomizadas y tratadas con estrógenos, con el objetivo de evaluar si esta estructura es un órgano blanco de las hormonas sexuales.

Los resultados mostraron que la lámina propia de la gingiva de los animales en estro permanente y, en los ooforectomizados tratados con estrógenos, era rica en células y en fibras colágenas. En estos dos grupos se observaron grandes concentraciones de eosinófilos y fibroblastos activos, como también, de macrófagos y linfocitos, observándose además en el estroma, áreas electrotranslúcidas. En el grupo ooforectomizado se observó gran concentración de células y, el estroma denso contenía innumerables fibras colágenas y substancia intercelular amorfa. En este grupo, los fibroblastos mostraron señales de atrofia y algunos macrófagos y leucocitos, señales degenerativas. El estroma gingival del grupo tratado con dexametasona, se mostró atrofiado, con gran número de células y fibras colágenas, como de fibroblastos y fibrocitos. Fue observado un reducido número de macrófagos y de leucocitos.

Se concluyó que la gingiva debe ser considerada como un órgano blanco de los estrógenos y que la ooforectomía no altera esa característica.

PALABRAS CLAVE: 1. Gingiva; 2. Microscopía electrónica; 3. Estrógenos; 4. dexametasona.

REFERENCES

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Dirección para correspondencia:
Prof. Dr. Manuel de Jesus Simões
Disciplina de Histologia
Departamento de Morfologia Universidade Federal de São Paulo-Escola Paulista de Medicina
Rua Botucatu 740
CEP 04023-900
São Paulo - SP
BRAZIL

E-mail: Manuel.morf@epm.br

Recibido : 20-01-1997

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