Journal ArticleDOI
Effect of Ovariectomy and Adrenalectomy on Luteinizing Hormone-Releasing Hormone in Pituitary Stalk Blood from Female Rats
Nancy M. Sherwood,George Fink +1 more
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TLDR
The concentration and content of immunoreactive LHRH in pituitary stalk plasma of rats which had been ovariectomized and adrenalectomizing (Ovx-Adx) for either 4 or 28 days were comparable to the levels in intact rats at the time of the proestrous surge of LH and significantly increased when compared with Levels in intact diestrous rats.Abstract:
The spontaneous release of LHRH has been measured in female rats subjected to ovariectomy and adrenalectomy to determine if the release of LHRH is altered in the absence of sex steroids. Release of LHRH was determined by RIA of blood collected from the cut pituitary stalk of rats anesthetized with alphaxalone-alphadolone acetate. The concentration and content of immunoreactive LHRH in pituitary stalk plasma of rats which had been ovariectomized and adrenalectomized (Ovx-Adx) for either 4 or 28 days were comparable to the levels in intact rats at the time of the proestrous surge of LH and significantly increased when compared with levels in intact diestrous rats. The increased levels of LHRH in Ovx-Adx rats were not altered by estradiol benzoate (50 μg) injected sc either 1 h before or at the beginning of the collection of portal blood. The concentration of immunoreactive LH in jugular venous plasma obtained before cutting the pituitary stalk was significantly increased in proestrous rats and in 28-day Ovx...read more
Citations
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Journal ArticleDOI
Molecular biology of the pituitary gonadotropins.
TL;DR: This review will discuss the structure of the gonadotropin subunits, theructure of the genes that encode them, and the regulation of their secretion and synthesis.
Journal ArticleDOI
Cellular Mechanisms of Melatonin Action
TL;DR: Molecular mechanisms of the melatonin effects are not clear but may involve at least two parallel transduction pathways, one inhibiting adenylyl cyclase and the other regulating phospholipide metabolism and [Ca2+]i.
Journal ArticleDOI
Gonadotropin-Releasing Hormone Receptors: Characterization, Physiological Regulation, and Relationship to Reproductive Function
Richard N. Clayton,Kevin J. Catt +1 more
TL;DR: It is revealed that GnRH is released in a pulsatile fashion, although rapid changes in secretion rate cannot be detected during the long period required for sample collection, and modulating the concentration of GnRH in hypophyseal portal plasma is suggested.
Journal ArticleDOI
Regulation of Pituitary Receptors for Gonadotropin-Releasing Hormone during the Rat Estrous Cycle
TL;DR: The close temporal relationship between rising blood estrogen levels and increasing pituitary GnRH receptors suggests that steroid-mediated receptor induction occurs before proestrus, and implies a physiological relevance for the GgRH-binding sites measured by radioassay.
Journal ArticleDOI
Homologous regulation of gonadotropin-releasing hormone receptors in cultured pituitary cells
Ernest Loumaye,Kevin J. Catt +1 more
TL;DR: Findings provide direct evidence for the homologous regulation of GnRH receptors by physiological concentrations of the hypothalamic peptide, an action that could mediate the cyclical and postcastration increases in Gn RH receptors and responsiveness of the pituitary gonadotrophs.
References
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Journal ArticleDOI
Extension of multiple range tests to group means with unequal numbers of replications
Abstract: In many fields of research, one is faced with the task of comparing the effects of treatments which have been replicated unequally. This happens for a number of reasons. In an experiment on animals, some may get sick and have to be removed from the experiment. In some experiments, the amount of material available for certain treatments may not be as much as for other treatments. If the experimenter has specified orthogonal contrasts that he is interested in before he runs the experiment, one can test the various treatment effects by an F-test after the treatment sum of squares has been partitioned into individual degrees of freedom for each orthogonal contrast. If the experimenter has not specified orthogonal contrasts, one is faced with the problem of deciding which treatments are significantly different. Several writers, including Duncan, Keuls, Newman, and Tukey, have developed multiple range tests to show differences among treatments that have been replicated the same number of times and when nothing was specified concerning the treatments. Duncan [1] compares the above methods and gives citations. This extension to unequal numbers of replications will be exemplified with reference to Duncan's "New Multiple Range Test," but is applicable to any of the above writers' tests; all one has to do is use their tabled ranges. In Duncan's test for an equal number of replications, the difference between any two ranked means is significant if the difference exceeds a shortest significant range. This shortest significant range is designated by R, and is obtained by multiplying the standard error of a mean, s,, by a given value, zn2, obtained from a table of significant studentized ranges which Duncan has tabled for both the 5% and 1% test. In Duncan's terminology, n2 is the degrees of freedom of the error mean square and p = 1, 2, * *, t is the number of means concerned. Consider an experiment with five treatments, A, B. C, D, and E, each replicated n times. Suppose on ranking the means from low to high one obtains
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Radioimmunoassay for Rat Luteinizing Hormone with Antiovine LH Serum and Ovine LH-131I∗:
TL;DR: A highly sensitive and specific radioimmunoassay for rat LH has been developed utilizing antiovine LH serum and ovine LH for iodination, and it has been possible to measure the LH in serum obtained from females throughout the estrus cycle and in serum from normal and castrated males.
Journal ArticleDOI
Gonadotropin-releasing hormone surge in pro-oestrous rats
TL;DR: Althesin an anaesthetic is used to show that, although it can provide adequate analgesia, Althesin does not interfere with various forebrain functions and block the spontaneous LH surge or ovulation.
Journal ArticleDOI
Pituitary Stalk Portal Blood Collection in Rhesus Monkeys: Evidence for Pulsatile Release of Gonadotropin-Releasing Hormone (GnRH)
TL;DR: Data provide direct evidence for a hypothalamic mediation of pituitary LH pulsatile release in rhesus monkeys and showuctuations in portal blood GnRH were most prominent in ovariectomized animals, with peak levels of 200-800 pg/ml and intervals of 1 to 3 hours between pulses.
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