Modulation of estrous cycle and LH, FSH and melatonin levels by pinealectomy and sham-pinealectomy in female rats

Dardes, Rita C.; Baracat, Edmund Chada; Simões, Manuel de Jesus

doi:10.1016/s0278-5846(99)00110-4

Cited by 25 publications

(19 citation statements)

References 28 publications

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“…Other authors (22) produced evidence showing that melatonin rescued the reduction in ovulation that resulted from removal of the pineal gland. However, others (23,24) suggested that melatonin was also capable of diminishing the number of ovarian cysts observed in pinealectomized animals, owing to the antigonadotropic effects of melatonin (24). There is evidence that melatonin acts through MT1 or MT2 receptors in the ovaries (11).…”

Section: Figurementioning

confidence: 99%

Effects of melatonin on histomorphology and on the expression of steroid receptors, VEGF, and PCNA in ovaries of pinealectomized female rats

Romeu

Motta

Maganhin

et al. 2011

Fertility and Sterility

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Section: Figurementioning

confidence: 99%

Effects of melatonin on histomorphology and on the expression of steroid receptors, VEGF, and PCNA in ovaries of pinealectomized female rats

Romeu

Motta

Maganhin

et al. 2011

Fertility and Sterility

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“…Previously published data from our laboratory showed that pinealectomy determined changes on the gonadotropin levels, ovarian function, endometrial morphology and embryo implantation in rats [12][13][14][15] . In brief, Dardes et al 13 demonstrated a decrease in gonadotropins (LH and FSH) at the early postpinealectomy period and a disruption in estrous cycle.…”

Section: Resultsmentioning

confidence: 99%

“…In brief, Dardes et al 13 demonstrated a decrease in gonadotropins (LH and FSH) at the early postpinealectomy period and a disruption in estrous cycle. Soares Jr. et al 14,15 revealed that the ovaries in pinealectomized rats had an increase in the number of atretic follicles and interstitial cells.…”

Section: Resultsmentioning

confidence: 99%

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Rat pinealectomy: a modified direct visual approach

et al. 2009

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Purpose: To report a new, direct visual approach for rat pinealectomy. Methods: Eighty adult female rats (Rattus norvegicus albinus EPM-1 strain) were weighted and anesthetized intraperitoneally with 15 mg/kg xylazine and 30 mg/kg ketamine. The animal was fastened to a dissection table, an incision was made in the skin and the subcutaneous tissue, bringing the lambda into view. The skullcap was opened with a dental drill, bringing the cerebral hemispheres and the superior sagittal sinus into view. The pineal gland, located under the venous sinus, was removed in a single piece using tweezers. Next, the bone fragment was returned to its place and the surgical layers were sutured. Results: This new technique is easy to be done, avoids bleedings and removes only the pineal gland without damage to the remaining encephalon. In addition it makes possible the achievement of a sham surgery, allowing the pineal gland to remain intact. Conclusion: The proposed technique intends to facilitate studies aiming to better understanding the complexity and importance of the pineal gland on reproductive and other body systems. Key words: Pineal Gland. Melatonin. Genitalia, Female. Surgery. Rats. RESUMOObjetivo: Apresentar nova técnica para pinealectomia em ratos. Métodos: 80 ratos adultos fêmeas (Rattus norvegicus albinus) foram pesados e em seguida anestesiados por via intraperitoneal com xilazina e cetamina. Em seguida os animais foram fixados em uma prancha de cortiça e feita uma incisão na pele e no tecido subcutâneo, na região superior da cabeça, evidenciando a junção dos ossos parietais e occipital. Na região do lambda, realizou-se uma perfuração circular, na calota craniana, com o auxilio de uma broca (4 mm) acoplada a um micromotor. Nesse orifício, após a dissecação da dura-mater visibiliza-se a confluência dos seios venosos longitudinal e transverso. Com o auxilio de uma pinça curva esses seios são deslocados, ligados e identificada a glândula pineal, que pode ser removida em peça única. Em seguida, o fragmento ósseo é devolvido ao seu lugar e as camadas cirúrgicas suturadas. Resultados: Esta nova técnica é fácil de ser feita, evita hemorragias e só remove a glândula pineal, sem prejuízos para o restante do encéfalo. Além disso, possibilita a realização de uma cirurgia sham, visto que a glândula pineal permanece sem alterações. Conclusão: Espera-se que a técnica proposta facilite estudos visando a uma melhor compreensão da complexidade e importância da glândula pineal sobre a reprodução e outros sistemas do organismo.

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“…The reduction in ovarian cysts in the placebo group may be explained as a partial compensation by extra-pineal melatonin-producing cells due to the fact that plasma melatonin levels are reduced by pinealectomy (5,6). Dardes et al (25) observed that in pinealectomized rats there is a reduction, but not the disappearance, of urinary 6-sulfatoxymelatonin excretion, indicating that there is synthesis of melatonin at sites other than the pineal gland. The lack of reduction in ovarian cortex thickness suggests that there was insufficient time for this event to be manifested, or that enlargement of the ovarian cortex did not occur.…”

Section: Discussionmentioning

confidence: 99%

Effects of melatonin on the ovarian response to pinealectomy or continuous light in female rats: similarity with polycystic ovary syndrome

Lima

Baracat

Simões

2004

Braz J Med Biol Res

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The current study was conducted to investigate the relationship between melatonin and chronic anovulation. Adult (3-4 months old) female Wistar rats were submitted to pinealectomy: group I: pinealectomized ovariectomized melatonin-treated (N = 10); group II: pinealectomized ovariectomized placebo-treated (N = 12); group III: pinealectomized light-treated placebo-treated (N = 10) or maintained under continuous light; group IV: maintained under continuous light, ovariectomized melatonin-treated (N = 22); group V: maintained under continuous light, ovariectomized placebo-treated (N = 10); group VI: maintained under continuous light placebo-treated (N = 10). In order to assess ovarian modifications, unilateral ovariectomy was performed during the fourth month in groups I, II, IV, V and the other ovary was removed after 8 months. Ovariectomy was performed in groups III and VI only after eight months. Melatonin (200 µg/100 g body weight) dissolved in 0.02 ml absolute ethanol was injected intramuscularly daily during the last 4 months into groups I and IV. The other groups were treated with placebo (NaCl). The ovarian cysts were analyzed and their area, perimeter and maximum diameter, as well as the thickness of the ovarian capsule were measured. Daily colpocytological smears were performed throughout the study. Persistent estrous condition and ovarian cysts were observed in all groups. In pinealectomized rats the ovarian and vaginal alterations disappeared at the end of the study and in rats maintained under continuous light the vaginal and ovarian polycystic aspect was reversed only in those treated with melatonin. We conclude that melatonin may act on the ovarian response reverting chronic anovulation induced by pinealectomy or continuous light.

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Modulation of estrous cycle and LH, FSH and melatonin levels by pinealectomy and sham-pinealectomy in female rats

Cited by 25 publications

References 28 publications

Effects of melatonin on histomorphology and on the expression of steroid receptors, VEGF, and PCNA in ovaries of pinealectomized female rats

Effects of melatonin on histomorphology and on the expression of steroid receptors, VEGF, and PCNA in ovaries of pinealectomized female rats

Rat pinealectomy: a modified direct visual approach

Effects of melatonin on the ovarian response to pinealectomy or continuous light in female rats: similarity with polycystic ovary syndrome

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