scholarly journals Regulation of prepubertal dynorphin secretion in the medial basal hypothalamus of the female rat

2019 ◽  
Vol 31 (12) ◽  
Author(s):  
William L. Dees ◽  
Jill K. Hiney ◽  
Vinod K. Srivastava
Keyword(s):  
Female Rat ◽  
Medial Basal Hypothalamus

scholarly journals Hypothalamic Expression of Eap1 Is Not Directly Controlled by Ovarian Steroids

Endocrinology ◽  
2008 ◽  
Vol 150 (4) ◽  
pp. 1870-1878 ◽  
Author(s):  
Valerie Matagne ◽  
Claudio Mastronardi ◽  
Robert A. Shapiro ◽  
Daniel M. Dorsa ◽  
Sergio R. Ojeda
Keyword(s):  
Preoptic Area ◽  
In Vitro Assays ◽  
Mrna Levels ◽  
Female Rat ◽  
Juvenile Period ◽  
Medial Basal Hypothalamus ◽  
Ovarian Steroids ◽  
Estrogen Responsive Element ◽  
General Decline ◽  
Responsive Element

A gene termed EAP1 (enhanced at puberty 1) was recently identified as a transcriptional regulator of female neuroendocrine reproductive function. We have now used in vivo and in vitro assays, and the female rat as an animal model, to determine whether Eap1 gene expression is regulated by ovarian steroids. Eap1 mRNA abundance decreases in both the hypothalamus and cerebral cortex during the infantile-juvenile phases of development, but it increases selectively in the hypothalamus at puberty, suggesting that in contrast to the general decline in expression observed in immature animals, the region-specific increase in Eap1 mRNA levels that occurs at puberty might be elicited by ovarian steroids. This is, however, not the case, because hypothalamic Eap1 mRNA levels increase at the expected time of puberty in rats ovariectomized at the beginning of the juvenile period. Although a subpopulation of EAP1-containing cells in the medial basal hypothalamus (MBH) and preoptic area express estrogen receptor-α (ERα), the 5′-flanking region of the rat Eap1 (rEap1) gene does not contain a complete estrogen-responsive element, and no such estrogen-responsive element is detected within 100 kb of the rEap1 locus. Functional promoter assays showed that neither estradiol (E2) alone nor a combination of E2 plus progesterone increases rEap1 gene transcription. Likewise, E2 administered to ovariectomized immature rats elicited a robust surge of LH but increased neither preoptic area nor MBH Eap1 mRNA levels. E2/progesterone-treated rats showed a massive elevation in plasma LH but only a modest increase in Eap1 mRNA levels, limited to the MBH. These results indicate that hypothalamic Eap1 expression is not directly controlled by ovarian steroids and suggest that Eap1 expression increases at puberty driven by ovary-independent, centrally initiated events.

scholarly journals Neuroendocrine Aging in the Female Rat: The Changing Relationship of Hypothalamic Gonadotropin-Releasing Hormone Neurons and N-Methyl-d-Aspartate Receptors**Preliminary versions of this work were presented at the 28th and 29th Annual Meetings of the Society for Neuroscience (Abstracts 110.11 and 777.10). This work was supported by the Brookdale Foundation (to A.C.G.), NIH Grant 1-PO1-AG16765–01 (to A.C.G. and J.H.M.).

Endocrinology ◽  
2000 ◽  
Vol 141 (12) ◽  
pp. 4757-4767 ◽  
Author(s):  
Andrea C. Gore ◽  
Glendy Yeung ◽  
John H. Morrison ◽  
Twethida Oung
Keyword(s):  
Critical Role ◽  
Reproductive Status ◽  
Female Rats ◽  
Mrna Levels ◽  
Female Rat ◽  
Messenger Rnas ◽  
Middle Aged ◽  
Medial Basal Hypothalamus ◽  
Aging Rats ◽  
Gnrh Neurons

Abstract The reproductive axis undergoes alterations during aging, resulting in acyclicity and the loss of reproductive function. In the hypothalamus, changes intrinsic to GnRH neurons may play a critical role in this process, as may changes in inputs to GnRH neurons from neurotransmitters such as glutamate. We investigated the effects of age and reproductive status on neuroendocrine glutamatergic NMDA receptors (NRs), their regulation of GnRH neurons, and their expression on GnRH neurons, in female rats. First, we quantified NR subunit messenger RNAs (mRNAs) in preoptic area-anterior hypothalamus (POA-AH) and medial basal hypothalamus (MBH), the sites of GnRH perikarya and neuroterminals, respectively. In POA-AH, NR1 mRNA levels varied little with age or reproductive status. NR2a and NR2b mRNA levels decreased significantly between cycling and acyclic rats. In MBH, NR mRNAs all increased with aging, particularly in acyclic animals. Second, we tested the effects of N-methyl-d,l-aspartate (NMA) on GnRH mRNA levels in POA-AH of aging rats. NMA elevated GnRH mRNA levels in young rats, but decreased them in middle-aged rats. Third, we quantified expression of the NR1 subunit on GnRH perikarya in aging rats using double label immunocytochemistry. NR1 expression on GnRH cell bodies varied with age and reproductive status, with 30%, 19%, and 46% of GnRH somata double labeled with NR1 in young proestrous, middle-aged proestrous, and middle-aged persistent estrous rats, respectively. Thus, 1) the expression of hypothalamic NR subunit mRNAs correlates with reproductive status; 2) changes in NR subunit mRNA levels, if reflected by changes in protein levels, may result in alterations in the stoichiometry of the NR during aging, with possible physiological consequences; 3) the effects of NR activation on GnRH mRNA switches from stimulatory to inhibitory during reproductive aging; and 4) expression of the NR1 subunit on GnRH perikarya changes with reproductive status. These molecular, physiological, and cellular neuroendocrine changes are proposed to be involved in the transition to acyclicity in aging female rats.

THE EFFECT OF HYPOTHALAMIC DEAFFERENTATION UPON PUBERTY IN THE FEMALE RAT

1967 ◽  
Vol 56 (4) ◽  
pp. 661-674 ◽  
Author(s):  
J. A. Ramaley ◽  
R. A. Gorski
Keyword(s):  
Optic Chiasm ◽  
Gonadal Development ◽  
Delayed Puberty ◽  
Corpora Lutea ◽  
Female Rat ◽  
Vaginal Opening ◽  
Sprague Dawley ◽  
Mamillary Body ◽  
Medial Basal Hypothalamus ◽  
Neural Connections

ABSTRACT Neural connections of the medial basal hypothalamus (MBH) were completely or partially severed in 180 22-day-old female Sprague-Dawley rats by means of the Halàsz knife and the subsequent gonadal development studied. Surgical transection of all neural input (complete deafferentation) or of only the fibers reaching the MBH from anterior resulted in precocious vaginal opening followed immediately by the onset of persistent vaginal oestrus. Surgery which transected the lateral and posterior connections had no effect, while sham surgery delayed puberty slightly. Animals with anterior or complete deafferentation of the MBH failed to ovulate at puberty. Upon necropsy at 90 days of age, the ovaries of the latter animals contained large follicles but no corpora lutea and weighed less than control ovaries. The deafferented region associated with precocity and persistent vaginal oestrus extended from just behind the optic chiasm to the mamillary body and about 1.2 mm dorsally and laterally. Prepuberal injection of 25 IU PMS accelerated vaginal opening and ovulation in intact controls. Ovulation did not occur after PMS in animals with anterior deafferentation of the MBH although the ovaries at necropsy equalled in weight those of intact PMS-treated controls. It appears that the neurally isolated MBH can sustain precocious maturation due presumably to the removal of inhibitory influences, but it cannot support regular ovulatory cycles.

OXYDATION DES ANABOLIKUMS 1-METHYL-ANDROST-1-EN-17β-OL-3-ON MIT WASSERSTOFFTRANSFER AUF ÖSTRON

1971 ◽  
Vol 67 (3) ◽  
pp. 517-530 ◽  
Author(s):  
Martin Wenzel
Keyword(s):  
Rat Liver ◽  
Anabolic Steroid ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Liver Slices ◽  
Androgen Effects ◽  
Biochemical Difference

ABSTRACT With the aid of metenolon-17α-T a tritium-transfer to oestrone in rat liver slices was demonstrated. This tritium-transfer from metenolon17α-T to oestrone yielding tritium-labelled oestradiol had a higher efficiency in male than in female rat liver. Correspondingly in the presence of metenolon the relation of oestrone to oestradiol is changed more in male than in female rat liver. Looking for biochemical differences between the anabolic steroid metenolon and testosterone the oxydation at C17 was measured in different organs of the rat using 17α-T-labelled steroids. The highest oxydation rate was found for both steroids in the liver. In the sexual organs of male rats the oxydation rate of testosterone was 50–10 times higher than that of the anabolic steroid. This difference was less in sexual organs of female rats. This result of a greater biochemical difference between both steroids in males than in females leads to the question, whether the dissociation between the anabolic and the androgen effects is higher in males than in females.

GONADOTROPHIN PATTERNS IN MALE AND FEMALE RATS:

1968 ◽  
Vol 58 (4) ◽  
pp. 600-612 ◽  
Author(s):  
Robert Boyd ◽  
Donald C. Johnson
Keyword(s):  
Ascorbic Acid ◽  
Testosterone Propionate ◽  
Female Rats ◽  
Female Rat ◽  
Feedback Effects ◽  
Male And Female ◽  
Prostate Weight ◽  
Male And Female Rats ◽  
Males And Females ◽  
Normal Males

ABSTRACT The effects of various doses of testosterone propionate (TP) upon the release of luteinizing hormone (LH or ICSH) from the hypophysis of a gonadectomized male or female rat were compared. Prostate weight in hypophysectomized male parabiotic partners was used to evaluate the quantity of circulating LH. Hypophyseal LH was measured by the ovarian ascorbic acid depletion method. Males castrated when 45 days old secreted significantly more LH and had three times the amount of pituitary LH as ovariectomized females. Administration of 25 μg TP daily reduced the amount of LH in the plasma, and increased the amount in the pituitary gland, in both sexes. Treatment with 50 μg caused a further reduction in plasma LH in males, but not in females, while pituitary levels in both were equal to that of their respective controls. LH fell to the same low level in partners of males or females receiving 100 μg TP. When gonadectomized at 39 days, males and females had the same amount of plasma LH, but males had more stored hormone. Pituitary levels were unchanged from controls following treatment with 12.5, 25 or 50 μg TP daily, but plasma values dropped an equal amount in both sexes with the latter two doses. Androgenized males or females, gonadectomized when 39 days old, were very sensitive to the effects of TP and plasma LH was significantly reduced with 12.5 μg daily. Pituitary LH in androgenized males was higher than that of normal males but was reduced to normal by small amounts of TP. The amount of stored LH in androgenized females was not different from that of normal females and it was unchanged by any dose of TP tested. Results are consistent with the conclusion that the male hypothalamic-hypophyseal axis is at least as sensitive as the female axis to the negative feedback effects of TP. Androgenization increases the sensitivity to TP in both males and females.

Sign in / Sign up

Export Citation Format

Share Document