Induction of precocious sexual maturation in female rats by electrochemical stimulation of the brain

1974 ◽  
Vol 78 (3) ◽  
pp. 437-446 ◽  
Author(s):  
K.B. Ruf ◽  
E.V. Younglai ◽  
M.J. Holmes
1964 ◽  
Vol 206 (4) ◽  
pp. 805-810 ◽  
Author(s):  
Raul C. Schiavi

The comparative effect of anterior and posterior hypothalamic lesions on the development of sexual maturation of prepubertal female rats was investigated. Lesions by electrocoagulation were made in the medial hypothalamus of 45 rats at 25–26 days of age. Thirty-nine animals of the same age constituted the sham-operated and nonoperated controls. A hastened appearance of vaginal opening and first estrus, a significant increase in uterine weight, precocious ovarian luteinization, and premature sexual cycles were observed following both types of lesions. Sham-operated rats and animals with lesions in other parts of the brain did not show evidence of precocious sexual maturation.


1971 ◽  
Vol 50 (4) ◽  
pp. 679-683 ◽  
Author(s):  
R. COLLU ◽  
F. FRASCHINI ◽  
L. MARTINI

SUMMARY Melatonin and 5-methoxytryptophol, the two methoxyindoles of pineal origin, were injected into a lateral ventricle of the brain of immature female rats. Treatment was started on the 25th day of age and terminated when the vagina opened. The injection of both methoxyindoles resulted in a statistically significant delay in vaginal opening. Since previous experiments had shown that melatonin specifically inhibits secretion of luteinizing hormone and that 5-methoxytryptophol specifically blocks release of follicle-stimulating hormone, the present results support the hypothesis that the onset of sexual maturation needs a balanced secretion of both gonadotrophins.


1988 ◽  
Vol 116 (1) ◽  
pp. 43-53 ◽  
Author(s):  
M. Laudon ◽  
Z. Yaron ◽  
N. Zisapel

ABSTRACT N-(3,5-dinitrophenyl)-5-methoxytryptamine (ML-23) has recently been synthesized and shown to antagonize the inhibitory effect of melatonin on the release of dopamine in vitro from the hypothalamus of female rats. In the present study the ability of ML-23 to inhibit in vivo the following melatonin-mediated effects was investigated: (1) delayed sexual maturation of young male rats, (2) delayed sexual maturation of young female rats, (3) inhibition of ovulation in mature female rats and (4) re-establishment of oestrous cycles in adult female rats maintained in continuous light. The inhibitory effect of daily melatonin injections, given in the afternoon, on the growth of the prostate gland and seminal vesicles and on serum testosterone concentrations in young male rats was prevented by daily injections of ML-23. Daily injections of ML-23 alone did not affect sexual maturation of young rats. In young male rats treated through the drinking water with melatonin, the growth of the accessory sex organs, but not that of the testes, was delayed and serum concentrations of testosterone were lower than in untreated rats. Administration of ML-23 through the drinking water increased serum concentrations of testosterone but did not significantly affect the weights of the accessory sex organs. Simultaneous administration of ML-23 and melatonin through the drinking water prevented completely, in a dose-dependent manner, the melatonin-mediated decrease in epididymal weights and in serum concentrations of testosterone and partially inhibited the delayed growth of the prostate glands and seminal vesicles. In young female rats treated with melatonin through the drinking water for 30 days, the growth of the ovaries was inhibited and serum concentrations of oestradiol were lower than in untreated rats. The growth of the uterus was not significantly affected. Administration of ML-23 through the drinking water did not significantly affect uterine and ovarian weights or oestradiol concentrations. Simultaneous administration of melatonin and ML-23 through the drinking water prevented completely the melatonin-mediated decrease in ovarian weights and in serum oestradiol concentrations. Ovulation during presumptive oestrus was prevented in adult female rats treated through the drinking water for 7 days with melatonin. Administration of ML-23 alone did not significantly affect the average numbers of ova shed and corpora lutea present. Simultaneous administration of ML-23 and melatonin prevented completely the melatonin-mediated inhibition of ovulation; the average number of ova shed was the same as in controls. Suppression of reproductive cycles occurred in adult female rats after long-term exposure to continuous light. This suppression was prevented by daily injections of melatonin in the afternoon; the incidence of constant oestrus decreased by 80%. Simultaneous injection of ML-23 and melatonin into rats maintained under continuous illumination prevented the effect of melatonin, and all the animals remained in constant oestrus. Administration of ML-23 alone did not alter the incidence of constant oestrus. A tritium-labelled derivative of ML-23 was prepared and administered orally to male rats. Peak concentrations of ML-23 occurred in the blood within 30 min after feeding and disappeared subsequently with a half-life of about 42 min. Intraperitoneal injection of [3H]ML-23 resulted in the appearance of peak concentrations of the drug in the brain within 20 min. The effects of ML-23 on serotonin S1 and S2 receptors, dopamine D2 receptors and melatonin receptors in the brain of the male rat were investigated using [3H]serotonin, [3H]spiperone and 2-[125I]iodomelatonin respectively. The binding of [3H]serotonin to brain synaptosomes and of [3H]spiperone to synaptosomes prepared from the cortical and caudate regions of the cerebrum was unaffected by ML-23 (10 μmol/l), whereas the binding of 2-[125I]iodomelatonin to brain synaptosomes was entirely inhibited. The results demonstrate the potency of ML-23 in antagonizing melatonin-mediated effects in the male and female rat in vivo. The drug may be administered to the animals simply through the drinking water, for relatively long periods without apparent deleterious effects on survival and welfare. ML-23 is accessible to both central and peripheral sites and acts specifically on melatonin but not on serotonin or dopamine receptors in the brain. The availability of a melatonin antagonist offers new opportunities for exploring the physiological role of melatonin in the neuroendocrine system. J. Endocr. (1988) 116, 43–53


Author(s):  
Gianluca Lavanco ◽  
Angela Cavallaro ◽  
Emanuele Cannizzaro ◽  
Marco Giammanco ◽  
Danila Di Majo ◽  
...  

Manipulations of the serotonin transmission during early development induce long-lasting changes in the serotonergic circuitry throughout the brain. However, little is known on the developmental consequences in the female progeny. Therefore, this study aimed at exploring the behavioural effects of pre- and postnatal stimulation of the serotonergic system by 5-methoxytryptamine in adolescent female rats on behavioural reactivity and anxiety- like phenotype. Our results show that perinatal 5- methoxythyptamine decreased total distance travelled and rearing frequency in the novel enviroment, and increased the preference for the centre of the arena in the open field test. Moreover, perinatal 5-methoxytryptamine increased the percentages of entries and time spent on the open arms of the elevated plus maze, with respect to perinatally vehicle-exposed rats. Thus, perinatal stimulation of serotonin receptors does not impair the functional response to the emotional challenges in female rats, favouring the occurrence of a stress-resilient phenotype.


2021 ◽  
Vol 6 (3) ◽  
pp. 114-119
Author(s):  
I. Yu. Mamay ◽  
◽  
O. A. Hryhorieva ◽  
V. I. Dariy

The response to perinatal hypoxia, developing in stimulating generic activity, is the activation of microglia, which induces the development of local inflammation of the brain and leads to the death of neurons. The formation of the hippocampus supports important physiological and behavioral functions, including spatial learning and memory, and is part of the brain, which is especially vulnerable to changes in blood glucose and oxygen. Thus, the study of the features of the development of hippocampal formation in the postnatal period after stimulating generic activity is relevant. The purpose of the study was to study the features of Glial fibrillary acidic protein and NeuN expression in the hippocampal formation in posterity of female rats after PgE2 injection for labor induction. Materials and methods. Pregnant females of the experimental group on the twenty-second day of pregnancy were injected intravaginally with PGE2 in the form of a gel to stimulate the generic activity. Birth occurred on the twenty-third day after conception. Birth in the intact group of rats occurred on the 23-24th day after conception. The large hemispheres of the rat brain were fixed in a 10% neutral formal solution, dehydrated in an ascending alcohol battery. For immunohistochemical studies, paraffin sections were used with 3 microns with a thickness of 3 microns. Glial fibrillary acidic protein Mouse Monoclonal Antibody (Santa Cruz Biotechnology, Inc.) is used to detect astrocytes (Santa Cruz Biotechnology, Inc.). NeuN Mouse Monoclonal Antibody (Santa Cruz Biotechnology, Inc.) was used to identify neurons on the 1st, 7th, 14th, 45th days after birth in histological cuts of hippocampus and gear, using a program for analyzing and processing images Image J, studied the relative area occupied by Glial fibrillary acidic protein + NeuN + cells. Data is processed by variation statistics. The results are reliable at p <0.05. All animal experiments were performed according to international principles of the European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes” (Strasbourg, 18.03.86) and the Law of Ukraine No. 1759-VI (15.12.2009) On the Protection of Animals from Cruelty. Results and discussion. We identified that by the changes in the hippocampus and the toothed gyrus of the rats after induction of labor, increased Glial fibrillary acidic protein expression on the first day after birth and reducing the NeuN expression on the 14th and 45th day of life in experimental animals compared to the control group were included. Conclusion. The density of the distribution of Glial fibrillary acidic protein + cells in the hippocampus and the dentate gyrus of rats changes wavily throughout the first month and a half of postnatal life. In the offspring of rats, after stimulation of labor on the first day of life, a reliable increase in the relative area occupied by Glial fibrillary acidic protein + astrocytes is determined compared to the control (49.3±2.6% and 36.8±5.9%, respectively). In the hippocampus and the dentate gyrus of rats after stimulation of labor during the first 45 days after birth, the gradual decrease in the relative area occupied by NeuN + neurons is determined, in contrast to the control animals, in which this index practically does not change. On the 14th and 45th days, the index of the relative area occupied by NeuN + neurons in experimental rats is reliably lower than in control (p <0.05).


Development ◽  
1967 ◽  
Vol 17 (1) ◽  
pp. 1-10
Author(s):  
W. N. Adams Smith

Pfeiffer (1935, 1936) reported the induction of constant oestrus in female rats following the transplantation of testes from litter-mate males just after birth and noted that the ovaries of these animals did not contain corpora lutea. These changes remained after removal of the testis transplants. The same effects were obtained by Bradbury (1941) following the administration of multiple doses of testosterone propionate. Barraclough & Leathern (1954) found that a single injection of 1 mg of testosterone propionate at 5 days of age led to permanent sterility in female mice, with no corpus luteum formation in their ovaries. Similar results were obtained in rats by Barraclough (1961) with the administration of a single injection of 1·25 mg of testosterone propionate. This permanent change in ovarian function does not appear to be a direct effect upon the ovary (Bradbury, 1941).


1975 ◽  
Vol 20 (12) ◽  
pp. 923-924
Author(s):  
MADGE E. SCHEIBEL ◽  
ARNOLD B. SCHEIBEL

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