Dehydroepiandrosterone administration reverses the inhibitory influence of aging on gonadotrophin-releasing hormone gene expression in the male and female rat brain

Endocrine ◽  
1997 ◽  
Vol 6 (3) ◽  
pp. 265-270 ◽  
Author(s):  
Songyun Li ◽  
Laurent Givalois ◽  
Georges Pelletier
Keyword(s):  
Gene Expression ◽  
Rat Brain ◽  
Inhibitory Influence ◽  
Female Rat ◽  
Male And Female ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

IN-VITRO STUDIES OF THE EFFECTS OF OESTROGEN PRETREATMENT ON THE SENSITIVITY OF THE IMMATURE FEMALE RAT PITUITARY GLAND TO STIMULATION WITH GONADOTROPHIN RELEASING HORMONE

1977 ◽  
Vol 74 (1) ◽  
pp. 11-21 ◽  
Author(s):  
M. WILKINSON ◽  
D. DE ZIEGLER ◽  
DANIELLE CASSARD ◽  
K. B. RUF
Keyword(s):  
Pituitary Gland ◽  
Brain Lesion ◽  
Culture Technique ◽  
Female Rats ◽  
Female Rat ◽  
Immature Female ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
Unilateral Brain Lesion

The effects of oestrogen priming on the sensitivity of the anterior pituitary gland to stimulation with gonadotrophin releasing hormone (GnRH) was investigated in immature female rats using a new organ culture technique. Hemipituitary glands obtained from animals primed with a single dose of oestradiol benzoate (OB; 20 μg/100 g body weight) released significantly more LH when pulsed with GnRH (4 nmol/l) than did control hemipituitary glands. This potentiating effect was detectable as early as 5 days after birth. After a second stimulation, LH secretion remained high. These results were compared with those obtained from animals treated to induce increased levels of endogenous oestrogen on day 26 of life. Thus, hemipituitary glands were obtained from animals given two injections of OB, an injection of pregnant mare serum gonadotrophin (PMSG) or a unilateral brain lesion placed in the basal hypothalamus. Pituitary tissue was stimulated as before with a pulse of GnRH. Two injections of OB enhanced the sensitivity to stimulation. Conversely, both PMSG and lesion treatment severely reduced the sensitivity to GnRH, although PMSG-treated and lesioned animals have been used as models for the study of ovulation.

Maternal Exposure to Δ 9 -Tetrahydrocannabinol ( Δ 9 -THC) Alters Indolamine Levels and Turnover in Adult Male and Female Rat Brain Regions

1997 ◽  
Vol 43 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Francisco Molina-Holgado ◽  
Francisco J. Alvarez ◽  
Isabel Gonzalez ◽  
Maria T. Antonio ◽  
Maria L. Leret
Keyword(s):  
Rat Brain ◽  
Adult Male ◽  
Brain Regions ◽  
Maternal Exposure ◽  
Female Rat ◽  
Male And Female ◽  
Rat Brain Regions

ANTERIOR PITUITARY SENSITIVITY IN IMMATURE FEMALE RATS STIMULATED WITH GONADOTROPHIN RELEASING HORMONE IN VIVO: EFFECT OF PRIMING WITH OESTROGEN, PREGNANT MARE SERUM GONADOTROPHIN OR BRAIN LESION

1977 ◽  
Vol 74 (1) ◽  
pp. 99-109 ◽  
Author(s):  
D. DE ZIEGLER ◽  
M. WILKINSON ◽  
DANIELLE CASSARD ◽  
K. B. RUF
Keyword(s):  
Brain Lesion ◽  
Treated Group ◽  
Female Rats ◽  
Similar Degree ◽  
Female Rat ◽  
Immature Female ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
Pregnant Mare Serum Gonadotrophin

An investigation of pituitary sensitivity, assessed in terms of increments in plasma LH and FSH concentrations, to stimulation with one or two injections of gonadotrophin releasing hormone (GnRH) was carried out on 26-day-old immature female rats which had received one of the following priming treatments: 10 μg oestradiol benzoate (OB) as a single injection on day 23 or day 25, or on both days; 10 i.u. pregnant mare serum gonadotrophin (PMSG) on day 24; an electrochemical brain lesion placed in the mediobasal hypothalamus on day 23; control animals received either vehicle alone or a sham lesion. Pituitary sensitivity assessed at 10.00 h on day 26, after one or two injections of GnRH (100 ng/100 g body weight, s.c.), was enhanced to a similar degree in the three groups treated with OB in terms of LH (P < 0-01). The FSH response also increased after OB treatment but was not statistically significant. In contrast, 48 h after the injection of PMSG (i.e. when the rats were in a 'pro-oestrous-like' condition) pituitary sensitivity in terms of both LH and FSH dropped sharply (P < 0·001). In lesioned animals, pituitary sensitivity to one injection of GnRH was unchanged. A second GnRH injection administered after a 60 min interval induced a slightly larger LH response in control animals. In contrast, the ratio of the second response to the first increased in animals treated with PMSG, despite the state of overall decrease in sensitivity, being 4·5:1 in PMSG-treated rats versus 1·4:1 in controls. In a second set of experiments, we investigated the variation of pituitary sensitivity in conjunction with an experimentally induced gonadotrophin surge. In animals treated with OB on day 23 and with 1 mg progesterone at 12·00 h on day 26, pituitary sensitivity was increased at both 14.00 and 17.00 h as compared with that in the day 23 OB-treated group at 10.00 h. The PMSG-treated animals maintained their state of decreased responsiveness at 14.00 h, but exhibited increased pituitary sensitivity at the time of the gonadotrophin surge (17.00 h). These results show that OB increases pituitary sensitivity to GnRH in 26-day-old female rats and that the induction of a gonadotrophin surge further increases this sensitivity. In contrast, PMSG-treated rats displayed a state of decreased responsiveness 48 and 52 h, but not 55 h, after the injection. Pituitary sensitivity on the second day after PMSG treatment thus clearly differs from that observed during pro-oestrus in the adult cyclic female rat.

Effects of corticotropin-releasing hormone and its antagonist on the gene expression of gonadotrophin-releasing hormone (GnRH) and GnRH receptor in the hypothalamus and anterior pituitary gland of follicular phase ewes

2011 ◽  
Vol 23 (6) ◽  
pp. 780 ◽  
Author(s):  
Magdalena Ciechanowska ◽  
Magdalena Łapot ◽  
Tadeusz Malewski ◽  
Krystyna Mateusiak ◽  
Tomasz Misztal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Follicular Phase ◽  
Gnrh Receptor ◽  
Corticotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
Lh Secretion ◽  
Crh Receptors

There is no information in the literature regarding the effect of corticotropin-releasing hormone (CRH) on genes encoding gonadotrophin-releasing hormone (GnRH) and the GnRH receptor (GnRHR) in the hypothalamus or on GnRHR gene expression in the pituitary gland in vivo. Thus, the aim of the present study was to investigate, in follicular phase ewes, the effects of prolonged, intermittent infusion of small doses of CRH or its antagonist (α-helical CRH 9-41; CRH-A) into the third cerebral ventricle on GnRH mRNA and GnRHR mRNA levels in the hypothalamo–pituitary unit and on LH secretion. Stimulation or inhibition of CRH receptors significantly decreased or increased GnRH gene expression in the hypothalamus, respectively, and led to different responses in GnRHR gene expression in discrete hypothalamic areas. For example, CRH increased GnRHR gene expression in the preoptic area, but decreased it in the hypothalamus/stalk median eminence and in the anterior pituitary gland. In addition, CRH decreased LH secretion. Blockade of CRH receptors had the opposite effect on GnRHR gene expression. The results suggest that activation of CRH receptors in the hypothalamus of follicular phase ewes can modulate the biosynthesis and release of GnRH through complex changes in the expression of GnRH and GnRHR genes in the hypothalamo–anterior pituitary unit.

Age-related changes in the soluble and the membrane-bound Tyr-aminopeptidase activities in several areas of the male and female rat brain

1996 ◽  
Vol 8 (3) ◽  
pp. 465 ◽  
Author(s):  
Gandarias JM de ◽  
J Irazusta ◽  
E Echevarria ◽  
J Gil ◽  
L Casis
Keyword(s):  
Rat Brain ◽  
Peptidase Activity ◽  
Female Rat ◽  
Major Pathway ◽  
Male And Female ◽  
Aminopeptidase M ◽  
Age Related ◽  
Female Brain ◽  
Membrane Bound ◽  
Cellular Development

It has been recently suggested that enkephalins might play a normal role in the regulation of cellular development in brain. Since the major pathway of enkephalin degradation seems to occur under the action of aminopeptidases, in the present paper we describe the changes in Tyr-aminopeptidase activities during several stages of the rat (male and female) brain development (9, 12, 15, 20 and 25 days postbirth). The enzyme activities (soluble and membrane-bound) were detected using Tyr-2-naphthylamide as substrate. No sexual differences were observed. However, significant rises from the 9th to the 15th postnatal day in the soluble peptidase activity were appreciated. Aminopeptidase M shows decreases in the activity with age. It is suggested that not only the enkephalins but also the enkephalin-degrading enzymes could play a part in the maturation of the rat brain.

Nicotine causes age-dependent changes in gene expression in the adolescent female rat brain

2007 ◽  
Vol 29 (1) ◽  
pp. 126-140 ◽  
Author(s):  
Oksana O. Polesskaya ◽  
Karl J. Fryxell ◽  
Amita D. Merchant ◽  
Laura L. Locklear ◽  
Ko-Fei Ker ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rat Brain ◽  
Adolescent Female ◽  
Female Rat ◽  
Age Dependent
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