INHIBITION OF NEUROHYPOPHYSIAL HORMONE RELEASE FROM THE ISOLATED RAT NEURAL LOBE BY FERROUS CHLORIDE IN THE INCUBATION MEDIUM

1977 ◽  
Vol 75 (2) ◽  
pp. 327-328 ◽  
Author(s):  
R. E. J. DYBALL ◽  
R. J. WRIGHT
Keyword(s):  
Luteinizing Hormone ◽  
Nerve Cells ◽  
Hormone Release ◽  
Ferrous Chloride ◽  
Ferric Ions ◽  
Luteinizing Hormone Releasing Hormone ◽  
Animal Physiology ◽  
Iron Salts ◽  
Lh Rh ◽  
Hypophysial Portal

A. R. C. Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT (Received 12 April 1977) Both electrical stimulation with steel microelectrodes and injection of iron salts into the preoptic area lead to an increased concentration of luteinizing hormone (LH) in the plasma and ovulation (Everett & Radford, 1961; Dyer & Burnet, 1976). Initially, iron salts were thought to excite nerve cells but Fe2+ and Fe3+ ions, like most cations, when applied to nerve cells by micro-iontophoresis, inhibit firing (Dyer & Burnet, 1976). Dyer & Burnet (1976) proposed a number of alternative explanations for the electrochemical stimulation of ovulation. They suggested that ferrous or ferric ions might kill or damage some neurones and the resulting cell disruption might lead in turn to the liberation of a sufficient quantity of luteinizing hormone releasing hormone (LH-RH) into the hypophysial portal vessels to cause a surge of LH. Alternatively, ovulation might be stimulated by

APPLICATION OF AN IN-VITRO PERIFUSION TECHNIQUE TO STUDIES OF LUTEINIZING HORMONE RELEASE BY RAT ANTERIOR HEMI-PITUITARIES: SELF-POTENTIATION BY LUTEINIZING HORMONE RELEASING HORMONE

1976 ◽  
Vol 68 (2) ◽  
pp. 197-207 ◽  
Author(s):  
J. A. EDWARDSON ◽  
D. GILBERT
Keyword(s):  
Luteinizing Hormone ◽  
Priming Effect ◽  
Hormone Release ◽  
Physiological Control ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Hypothalamic Extract ◽  
Lh Rh ◽  
Lh Secretion

SUMMARY A technique is described for the continuous perifusion of rat adenohypophyses. Exposure of the perifused glands to repeated equal 5 min stimuli with hypothalamic extract resulted in a series of equal peaks of corticotrophin secretion, the response was proportional to log dose over the range 0·25–2·0 rat hypothalamic equivalents/ml. Repeated equal stimuli with hypothalamic extract, or with luteinizing hormone releasing hormone (LH-RH) at concentrations of 2 or 10 ng/ml, resulted in a progressively increasing series of peaks of LH secretion, i.e. a self-potentiating or priming effect. The effect took between 30 min and 1 h to develop. A delayed increase in the responsiveness of the glands was also seen with continuous incubation of anterior pituitaries with LH-RH. The relevance of these observations to the physiological control of LH secretion is discussed.

VASOTOCIN RELEASE INTO THE CEREBROSPINAL FLUID OF CATS INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE, THYROTROPHIN RELEASING HORMONE AND GROWTH HORMONE RELEASE-INHIBITING HORMONE

1977 ◽  
Vol 75 (1) ◽  
pp. 175-176 ◽  
Author(s):  
R. GOLDSTEIN ◽  
S. PAVEL
Keyword(s):  
Growth Hormone ◽  
Cerebrospinal Fluid ◽  
Luteinizing Hormone ◽  
Pineal Gland ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Thyrotrophin Releasing Hormone ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Rh

Institute of Endocrinology, Bucharest, Rumania (Received 29 March 1977) The mammalian pineal gland contains (Pavel, 1965) and synthesizes (Pavel, Goldstein, Ghinea & Calb, 1977) the nonapeptide arginine-vasotocin (AVT). Since luteinizing hormone releasing hormone (LH–RH), thyrotrophin releasing hormone (TRH) and growth hormone release-inhibiting hormone (somatostatin, SRIF) have now been localized not only in the brain, but also in the pineal gland (White, Hedlund, Weber, Rippel, Johnston & Wilber, 1974; Pelletier, Le Clerc, Dube, Labrie, Puviani, Arimura & Schally, 1975), we investigated the effects of these peptides on the release of AVT into the cerebrospinal fluid (CSF) of cats. Intracarotid injections of 0·1 μg LH-RH, TRH (Hoechst, Frankfurt), SRIF (Serono, Rome) or oxytocin (Syntocinon, Sandoz Ltd, Basel) in 0·5 ml saline were given to urethane-anaesthetized male cats weighing 3–4 kg. Controls received an equal volume of saline only. The pineal glands were removed 60 min after the injections, quickly homogenized, and extracted

LUTEINIZING HORMONE RELEASE AFTER TWO INJECTIONS OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE IN THE EWE

1977 ◽  
Vol 72 (1) ◽  
pp. 59-67 ◽  
Author(s):  
D. B. CRIGHTON ◽  
J. P. FOSTER
Keyword(s):  
Luteinizing Hormone ◽  
Steroid Hormones ◽  
The Other ◽  
Sex Steroid ◽  
Hormone Release ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Significant Difference ◽  
Lh Release ◽  
Lh Rh

SUMMARY Anoestrous ewes were given two injections of 30 μg synthetic luteinizing hormone releasing hormone (LH-RH) separated by one of the following intervals: 1·5, 3, 6, 12 or 24 h. The first injection caused an increase in the plasma LH concentration in each animal. The response to the second injection was dependent on the interval between the injections. When the second injection was administered 1·5 h after the first it caused a further increase in the LH concentration to maximal levels which were significantly greater than those induced in the other anoestrous groups. When the second injection was administered 3 h after the first, there was no significant difference between the responses to the two injections although the time to reach the maximal LH concentration was shorter and the height of the LH peak was greater in each animal following the second injection. When the second injection was administered 6,12 or 24 h after the first, the LH response was significantly less, in terms of height and area of the induced peak, than following the first injection. The LH response to the second injection was particularly low in the 12 and 24 h groups. Two injections of 30 μg synthetic LH-RH were also administered at 1·5 h intervals to ewes on either day 10 of the oestrous cycle or at onset of oestrus. The pattern of LH responses in all these animals was similar to that observed in anoestrous ewes injected at 1·5 h intervals. The total LH release, as assessed in terms of area of the induced peaks, was significantly greater in the onset of oestrus group than in the day 10 group or any of the anoestrous groups. Presumably the sensitization–desensitization sequence of the pituitary gland to LH-RH which has been demonstrated, together with the effects of sex steroid hormones, must play an important part in the development and decay of the natural preovulatory LH peak.

EFFECT OF CORTISOL OR ADRENOCORTICOTROPHIN ON RELEASE OF LUTEINIZING HORMONE INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE IN THE DAIRY HEIFER

1982 ◽  
Vol 92 (1) ◽  
pp. 141-146 ◽  
Author(s):  
R. L. MATTERI ◽  
G. P. MOBERG
Keyword(s):  
Luteinizing Hormone ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Dairy Heifers ◽  
Significant Difference ◽  
Significant Depression ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
And Control ◽  
Slight Depression

During treatment with cortisol or ACTH, dairy heifers were given two doses of LH releasing hormone (LH-RH) spaced 1·5 h apart. Serum concentrations of cortisol and LH were monitored during each treatment. Treatment with both ACTH and cortisol raised plasma cortisol levels above the respective saline controls (P<0·001). Neither treatment affected basal LH concentrations. A slight depression in LH response was seen in the cortisol-treated animals after the first LH-RH injection, as shown by a statistically significant depression at three of the sample times. There was no significant difference between treated and control LH values after the second LH-RH administration. Treatment with ACTH resulted in significantly reduced LH values at all sample times after both injections of LH-RH.

Acidic Aqueous Extraction of Hypothalamic Luteinizing Hormone Releasing Hormone to Study Biological Effects

1974 ◽  
Vol 52 (3) ◽  
pp. 754-758 ◽  
Author(s):  
S. H. Shin ◽  
C. J. Howitt
Keyword(s):  
Luteinizing Hormone ◽  
Biological Effects ◽  
Extraction Procedure ◽  
Extraction Methods ◽  
Water Soluble ◽  
Acid Extraction ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Aqueous Solvent ◽  
Lh Rh

Several aqueous solvent systems were tested for their efficiency in extracting luteinizing hormone releasing hormone (LH-RH) from rat hypothalamus. Although LH-RH is a water-soluble decapeptide, neutral distilled water extracted only 10% of the LH-RH obtained using acid extraction methods. The efficiency of the acid extraction procedure suggests that in the hypothalamus the releasing hormone is bound to a relatively large molecular weight compound. Using the acidic extraction procedure, we found that hypothalamic LH-RH content is significantly lower in the castrated animal than in the normal rat.

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