Endometrium estradiol receptors type I and type II during early pregnancy of rat

Rat pinealectomy: a modified direct visual approach

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.

Hormone catalysis: role of protecting and modifying reagents of sulfhydryl groups on estrogen receptor in breast cancer

We have studied the modulation and differential sensitivity of the estrogen receptor (ER) in breast cancer in the presence of protecting or modifying agents of disulfide bonds and sulfhydryl groups present in the ER steroid-binding domain. Protecting agents such as mercaptoethanol and dithiotreitol increased the [(3)H]estradiol binding to ER by 25% and 50%, respectively. Modifying agents such as p-chloromercuribenzensulfonate decreased the [(3)H]estradiol binding by 70% and this was nearly completely abolished by N-ethylmaleimide (94%). These data indicate that disulfide bonds and sulfhydryl groups in the steroid-binding domain are intimately involved in the maintenance of a receptor structure necessary for estradiol binding.

Effects of melatonin on the endometrial morphology and embryo implantation in rats

OBJECTIVE

To determine the effects of melatonin on rat endometrium morphology and embryo implantation.

DESIGN

Experimental study.

SETTING

Federal University of São Paulo, Brazil.

ANIMAL(S)

Forty female rats.

INTERVENTION(S)

GI: control, GII: sham-operated, GIII: pinealectomized, and GIV: pinealectomized rats that received melatonin during 3 months. The GI, GII, and GIII groups received the vehicle of melatonin (NaCl + ethanol). At the end of the treatment, the animals were killed during the estrous phase; the uterus was removed for morphometric analysis. Urine was collected for 6-sulfatoxymelatonin. Blood was collected for estrogen (E) and progesterone (P) level determinations. In a second experiment, female rats were used to evaluate the endometrial embryo implantation.

MAIN OUTCOME MEASURE(S)

Endometrial morphology and embryo implantation.

RESULT(S)

GIII presented the highest values for endometrial area and thickness index, number of endometrial glands, and eosinophils. The number of vessels of groups I, II, and IV was fewer than that of GIII. The highest number of eosinophils was detected in GIII in comparison to other groups. The implantation rate in GIII was the lowest of all groups. This implantation rate was significantly increased and restored toward normal in GIV.

CONCLUSION(S)

Our data suggested that, in nonphotoperiodic animals such as rats, melatonin may positively affect the endometrial morphology and improve embryo implantation.