33 results on '"McCann SM"'
Search Results
2. Anesthetic management of a parturient with fetal sacrococcygeal teratoma and mirror syndrome complicated by elevated hCG and subsequent hyperthyroidism.
- Author
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McCann SM, Emery SP, and Vallejo MC
- Subjects
- Edema etiology, Female, Fetus surgery, Humans, Hypertension, Pregnancy-Induced etiology, Hyperthyroidism blood, Labor, Induced, Pregnancy, Proteinuria complications, Young Adult, Anesthesia, Obstetrical, Chorionic Gonadotropin blood, Fetal Diseases, Hydrops Fetalis, Hyperthyroidism complications, Pregnancy Complications therapy, Teratoma complications
- Abstract
Mirror syndrome is a condition in which the mother "mirrors" her hydropic fetus and/or hydropic placenta. Physical and laboratory findings of mirror syndrome include generalized edema, hypertension, and proteinuria similar to preeclampsia. However, unlike preeclampsia, mirror syndrome is associated with hemodilutional anemia and fluid overload, which may progress to pulmonary edema. The anesthetic management of a parturient with fetal sacrococcygeal teratoma, hydrops fetalis, and mirror syndrome complicated by markedly elevated maternal serum human chorionic gonadotropin and subsequent clinical hyperthyroidism, is presented.
- Published
- 2009
- Full Text
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3. Mechanisms of inhibition of LHRH release by alcohol and cannabinoids.
- Author
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Rettori V, Lomniczi A, Mohn C, Scorticati C, Vissio P, Lasaga M, Franchi A, and McCann SM
- Subjects
- Animals, Brain drug effects, Dronabinol, Models, Neurological, Neurotransmitter Agents physiology, Rats, Brain physiology, Cannabinoids pharmacology, Ethanol pharmacology, Gonadotropin-Releasing Hormone antagonists & inhibitors, Gonadotropin-Releasing Hormone metabolism
- Published
- 2002
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4. Hypothalamic control of gonadotropin secretion.
- Author
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McCann SM, Karanth S, Mastronardi CA, Dees WL, Childs G, Miller B, Sower S, and Yu WH
- Subjects
- Animals, Brain Chemistry, Cytokines physiology, Follicle Stimulating Hormone metabolism, Gonadotropin-Releasing Hormone analysis, Leptin physiology, Rats, Sexual Behavior, Animal, Gonadotropin-Releasing Hormone metabolism, Hypothalamus physiology
- Published
- 2002
- Full Text
- View/download PDF
5. Oxytocin, vasopressin and atrial natriuretic peptide control body fluid homeostasis by action on their receptors in brain, cardiovascular system and kidney.
- Author
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McCann SM, Antunes-Rodrigues J, Jankowski M, and Gutkowska J
- Subjects
- Animals, Homeostasis, Humans, Receptors, Atrial Natriuretic Factor physiology, Receptors, Oxytocin physiology, Receptors, Vasopressin physiology, Atrial Natriuretic Factor physiology, Body Fluids physiology, Brain physiology, Cardiovascular Physiological Phenomena, Kidney physiology, Oxytocin physiology, Vasopressins physiology
- Published
- 2002
- Full Text
- View/download PDF
6. Lamprey gonadotropin-releasing hormone-III selectively releases follicle stimulating hormone in the bovine.
- Author
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Dees WL, Dearth RK, Hooper RN, Brinsko SP, Romano JE, Rahe H, Yu WH, and McCann SM
- Subjects
- Animals, Dose-Response Relationship, Drug, Estrus, Female, Gonadotropin-Releasing Hormone administration & dosage, Luteal Phase, Luteinizing Hormone metabolism, Progesterone blood, Cattle physiology, Follicle Stimulating Hormone metabolism, Gonadotropin-Releasing Hormone pharmacology
- Abstract
Recent studies have shown that lamprey gonadotropin-releasing hormone (l-GnRH) is localized in the mammalian brain, and that l-GnRH-III, can selectively induce FSH secretion in the rat both in vivo and in vitro. Consequently, the purpose of this study was to determine if l-GnRH-III could elicit selective FSH release in cattle and compare this response with that to mammalian luteinizing hormone releasing hormone (m-LHRH). Cattle were chosen as the animal model because previous studies have demonstrated that FSH and LH are secreted by separate gonadotropes in that species. For these studies, crossbred cycling heifers were implanted with jugular cannulae and l-GnRH-III was infused either between Days 9-14 or on Day 20 of the estrous cycle. Blood samples were collected both before and following peptide infusion. Our results demonstrate that during Days 9-14 of the estrous cycle (luteal phase), when progesterone levels averaged between 4 and 5 ng/ml, a dose of 0.25 mg of l-GnRH-III induced the release of FSH (P < 0.05), but not LH. A 0.5 mg dose of l-GnRH-III caused a greater release of FSH (P < 0.01), but still did not induce LH release. Higher doses of the peptide were capable of significantly releasing both gonadotropins. Importantly, during the luteal phase, doses of 0.5 and 2 mg of m-LHRH were ineffective in stimulating FSH, but did elicit marked increases (P < 0.001) in LH. Again, progesterone levels averaged 4-5 pg/ml. In order to assess gonadotropin releasing ability of l-GnRH-III at a different phase of the estrous cycle, some animals were administered the peptide on Day 20, when progesterone levels were below 1.0 pg/ml. At this time, the l-GnRH-III induced the release of LH (P < 0.01), but not FSH. Overall, our results demonstrate that l-GnRH-III can selectively induce FSH in cattle during the luteal phase, whereas m-LHRH was ineffective in that regard. Furthermore, the fact that l-GnRH-III can selectively stimulate FSH when serum progesterone is high, and LH when serum progesterone is low, suggests its actions are under strong control of this steroid. We suggest the FSH releasing capacity of l-GnRH-III in cattle could render this peptide useful for enhancement of reproductive efficiency in this species.
- Published
- 2001
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7. Hypothalamic control of gonadotropin secretion by LHRH, FSHRF, NO, cytokines, and leptin.
- Author
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McCann SM, Kimura M, Walczewska A, Karanth S, Rettori V, and Yu WH
- Subjects
- Animals, Female, Gonadotropins, Pituitary physiology, Granulocyte-Macrophage Colony-Stimulating Factor metabolism, Granulocyte-Macrophage Colony-Stimulating Factor physiology, Hypothalamus metabolism, Interleukin-1 metabolism, Interleukin-1 physiology, Lampreys, Leptin, Male, Pituitary Gland metabolism, Pituitary Gland physiology, Rats, Cytokines physiology, Gonadotropin-Releasing Hormone physiology, Gonadotropins, Pituitary metabolism, Hypothalamus physiology, Nitric Oxide physiology, Proteins physiology
- Abstract
Gonadotropin secretion by the pituitary gland is under the control of luteinizing hormone-releasing hormone (LHRH) and the putative follicle stimulating hormone-releasing factor (FSHRF). Lamprey III LHRH is a potent FSHRF in the rat and seems to be resident in the FSH controlling area of the rat hypothalamus. It is an analog of mammalian LHRH and may be the long sought FSHRF. Gonadal steroids feedback at hypothalamic and pituitary levels to either inhibit or stimulate the release of LH and FSH, which is also affected by inhibin and activin secreted by the gonads. Important control is exercised by acetylcholine, norepinephrine (NE), dopamine, serotonin, melatonin, and glutamic acid (GA). Furthermore, LH and FSH also act at the hypothalamic level to alter secretion of gonadotropins. More recently, growth factors have been shown to have an important role. Many peptides act to inhibit or increase release of LH and the sign of their action is often reversed by estrogen. A number of cytokines act at the hypothalamic level to suppress acutely the release of LH but not FSH. NE, GA, and oxytocin stimulate LHRH release by activation of neural nitric oxide synthase (nNOS). The pathway is as follows: oxytocin and/or GA activate NE neurons in the medial basal hypothalamus (MBH) that activate NOergic neurons by alpha, (alpha 1) receptors. The NO released diffuses into LHRH terminals and induces LHRH release by activation of guanylate cyclase (GC) and cyclooxygenase. NO not only controls release of LHRH bound for the pituitary, but also that which induces mating by actions in the brain stem. An exciting recent development has been the discovery of the adipocyte hormone, leptin, a cytokine related to tumor necrosis factor (TNF) alpha. In the male rat, leptin exhibits a high potency to stimulate FSH and LH release from hemipituitaries incubated in vitro, and increases the release of LHRH from MBH explants. LHRH and leptin release LH by activation of NOS in the gonadotropes. The NO released activates GC that releases cyclic GMP, which induces LH release. Leptin induces LH release in conscious, ovariectomized estrogen-primed female rats, presumably by stimulating LHRH release. At the effective dose of estrogen to activate LH release, FSH release is inhibited. Leptin may play an important role in induction of puberty and control of LHRH release in the adult as well.
- Published
- 1998
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8. Role of laminin on prolactin and gonadotrophin release from anterior pituitaries of male rats.
- Author
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Denduchis B, Rettori V, and McCann SM
- Subjects
- Animals, Immunohistochemistry, Male, Rats, Rats, Sprague-Dawley, Follicle Stimulating Hormone metabolism, Laminin physiology, Luteinizing Hormone metabolism, Pituitary Gland, Anterior metabolism, Prolactin metabolism
- Abstract
The effect of rat laminin on the release of prolactin (PRL), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from anterior pituitaries of adult male rats was studied in vitro. Laminin had a bidirectional effect on basal release of PRL, being stimulatory at 10(-12)M and inhibitory at 10(-9) and 10(-8)M. LH release was only stimulated by the 10(-12)M concentration and no changes in FSH release were observed. Laminin did not modify the stimulatory action of thyrotropin-releasing hormone (TRH) nor luteinizing hormone releasing hormone (LHRH), but the response of FSH to LHRH was inhibited with a maximal effect at 10(-10)M. To assess its physiological role, the effect of a rabbit antibody to laminin on the release of PRL, LH and FSH was also studied. IgG anti-laminin at 2 x 10(-7)M had a highly significant stimulatory effect on PRL release after 3 and 5 hr of incubation, as compared to IgG from normal rabbit serum and medium alone used as controls. No changes on the release of LH and FSH were detected. These results suggest that laminin plays a physiologically significant inhibitory role on PRL release at the pituitary level in vitro.
- Published
- 1994
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9. Effects of alpha-inhibin-92 fragments and alpha-inhibin-92 antiserum on the control of follicle-stimulating hormone release in male rats.
- Author
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Yu WH, Riedel M, Yamashiro D, Ramasharma K, and McCann SM
- Subjects
- Animals, Female, Follicle Stimulating Hormone blood, Immune Sera, Inhibins immunology, Luteinizing Hormone blood, Male, Orchiectomy, Rabbits, Rats, Rats, Sprague-Dawley, Structure-Activity Relationship, Follicle Stimulating Hormone metabolism, Inhibins pharmacology, Inhibins physiology, Peptide Fragments pharmacology
- Abstract
Alpha-inhibin-92 (alpha-IB-92) has been characterized from human seminal plasma and found to be active in suppressing FSH release in vitro and in vivo. In order to determine if smaller fragments of this 92 amino acid peptide would still be active to suppress FSH release, we have evaluated 5 of these fragments for their effects on FSH and LH release in the present study. Five alpha-IB-92 fragments (1-34, 1-46, 35-65, 35-92 and 66-92) were synthesized and injected intravenously (iv) into castrated adult rats (2 days post operation). Only fragments alpha-IB-92-(35-65) and alpha-IB-92-(66-92) significantly lowered plasma FSH, but not LH, at doses of 10 micrograms. These fragments exerted a preferential FSH-suppressing effect, but their activities were less than that of alpha-IB-92. In view of the rapid action of these peptides and the preferential FSH suppressing effect, they could be useful clinically to suppress FSH release. To determine the possible physiologic significance of alpha-IB-92, we injected antiserum raised against alpha-IB-92 into immature male rats and evaluated its effects on FSH and LH release. Normal rabbit serum (NRS) or anti-alpha-IB-92 serum was injected iv through indwelling jugular catheters into conscious, unrestrained 18 day-old male rats. Blood samples (0.2 ml) were collected at various intervals. Intravenous injection of alpha-IB-92 antiserum (0.1 ml/rat) selectively elevated plasma levels of FSH but not LH from 2-8 h post-injection in 18 day-old male rats (P < 0.01). Since immunoneutralization of alpha-IB-92 significantly elevated FSH release in immature rats, alpha-IB-92 has a physiological inhibiting role in control of FSH but not LH release at this stage of development.
- Published
- 1994
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10. Rat growth hormone-releasing factor stimulates cyclic GMP formation and phosphatidylinositol metabolism in the median eminence.
- Author
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Aguila MC, Snyder GD, and McCann SM
- Subjects
- Animals, Cyclic AMP biosynthesis, Epinephrine metabolism, Inositol Phosphates metabolism, Male, Radioimmunoassay, Rats, Rats, Inbred Strains, Second Messenger Systems, Somatostatin metabolism, Cyclic GMP biosynthesis, Growth Hormone-Releasing Hormone metabolism, Median Eminence metabolism, Phosphatidylinositols metabolism
- Abstract
The effects of rat growth hormone releasing factor (rGRF) on somatostatin (SRIF) secretion, cyclic nucleotide production and phosphatidylinositol metabolism were investigated in the median eminence (ME), using an in vitro system. Medium was discarded and replaced by medium containing various concentrations of rGRF or rGRF plus epinephrine (E, 6 x 10(-7) M). rGRF had no effect on basal or E-stimulated release of cAMP. In the same experiments rGRF markedly stimulated SRIF release. These results suggested that cAMP is not involved in the stimulatory effect of GRF on SRIF release. However, GRF significantly stimulated release of both SRIF and cGMP in a dose-related manner. Maximal stimulation was observed at 10(-10) M GRF (p less than 0.005) which also produces maximal SRIF release. 2'0-monobutyrylguanosine 3'5' cyclic phosphate (mbcGMP, 10(-11) to 10(-10) M) stimulated SRIF release from ME fragments (p less than 0.001 at 10(-10) M) whereas the control, sodium butyrate (10(-6) M), had no effect. GRF caused significant elevation of 30.6% in the concentration of labelled inositol phosphates [( 3H]-IPs) in the ME. These data indicate that GRF stimulation of SRIF release is accompanied by increased cGMP production and phosphatidyl-inositol (PI) metabolism but does not alter cAMP production. Because mbcGMP can directly stimulate SRIF release, we suggest that GRF causes a receptor-mediated increase in the metabolism of phosphatidylinositol and cGMP formation. These actions therefore may be among the early metabolic events in the mechanism of GRF-stimulated SRIF release from the ME.
- Published
- 1991
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11. Differential role of the opioid mu and delta receptors in the activation of prolactin (PRL) and growth hormone (GH) secretion by morphine in the male rat.
- Author
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Koenig JI, Mayfield MA, McCann SM, and Krulich L
- Subjects
- Animals, Drug Interactions, Enkephalin, Leucine analogs & derivatives, Enkephalin, Leucine pharmacology, Injections, Intraventricular, Male, Naloxone analogs & derivatives, Naloxone pharmacology, Naltrexone analogs & derivatives, Naltrexone pharmacology, Rats, Rats, Inbred Strains, Growth Hormone metabolism, Morphine pharmacology, Prolactin metabolism, Receptors, Opioid metabolism
- Abstract
Administration of naloxazone (50 mg/kg i.v.), an irreversible, selective and long acting antagonist of the mu 1 subclass of the opioid receptors, strongly reduced stimulation of PRL secretion by morphine (5.0 mg/kg i.v.) injected 24 hours later into conscious, unrestrained rats. In contrast, the effect of morphine on PRL release was unimpaired in rats treated 24 hours beforehand with either the reversible opioid antagonist naloxone (50 mg/kg i.v.), or the vehicle for naloxazone. A complete suppression of the PRL response to morphine (3.0 mg/kg i.v.) was observed in animals given intraventricular (IVT) injection of beta- funaltrexamine (beta-FNA, 2.5 micrograms), another selective, irreversible and long acting antagonist of the mu receptors, 24 hours beforehand. Neither naloxazone nor beta-FNA had any effect on the activation of GH secretion by morphine, which, however, was conspicuously reduced by ICI 154, 129, a preferential delta receptor antagonist, injected IVT (50 micrograms) 5 minutes before morphine. ICI 154, 129 had no effect on the PRL response to morphine. It is concluded that the PRL stimulating effect of morphine is mediated by the mu receptors, whereas activation of GH probably involves the delta sites.
- Published
- 1984
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12. Characterization of muscarinic cholinergic receptors on intact rat anterior pituitary cells.
- Author
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Mukherjee A, Snyder G, and McCann SM
- Subjects
- Animals, Atropine pharmacology, Growth Hormone metabolism, In Vitro Techniques, Kinetics, Male, Parasympathomimetics pharmacology, Pituitary Gland, Anterior cytology, Prolactin metabolism, Quinuclidinyl Benzilate, Rats, Pituitary Gland, Anterior metabolism, Receptors, Cholinergic drug effects, Receptors, Muscarinic drug effects
- Published
- 1980
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13. The effects of the cholecystokinin antagonist, proglumide, on prolactin secretion in the rat.
- Author
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Vijayan E and McCann SM
- Subjects
- Animals, Female, Injections, Intravenous, Injections, Intraventricular, Male, Proglumide administration & dosage, Rats, Rats, Inbred Strains, Cholecystokinin antagonists & inhibitors, Glutamine analogs & derivatives, Proglumide pharmacology, Prolactin metabolism
- Abstract
Since cholecystokinin produced important effects on prolactin secretion following its intraventricular injection in ovariectomized rats, we have evaluated the effects of the cholecystokinin antagonist, proglumide, to assess the physiologic significance of CCK in the control of prolactin release. Conscious rats of either sex were used following implantation of third ventricular and/or intravenous cannulae for the administration of proglumide. Blood samples were drawn from conscious animals at various times after injection of the compound. Intraventricular injection of 1 or 10 micrograms of proglumide produced a dramatic decline in plasma prolactin levels in either castrate or intact male rats. Similar results were found following the intravenous injection of 10 or 100 micrograms of the drug. These results contrasted sharply with the findings in ovariectomized females in which the intraventricular injection of the same two doses of proglumide used in males produced a dose-related elevation of prolactin which was opposite to the delayed lowering of prolactin following the intravenous injection of the same doses of the compound used in males. These results indicate that proglumide can lower prolactin in male rats and suggests a physiologically significant role of CCK in the control of prolactin secretion in the male. There appears to be a sex difference in the response since the results contrasted sharply in ovariectomized female rats. The results in the females are puzzling and it is apparent that further studies are needed to determine whether or not CCK has a physiologically significant role to play in prolactin secretion in the female. Since previous results have shown that CCK has no effect on the release of prolactin by the pituitary directly these interactions are presumably taking place in the hypothalamus.
- Published
- 1987
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14. Vasoactive-intestinal-polypeptide concentrations in median eminence of hypothalamus.
- Author
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Samson WK, Said SI, Graham JW, and McCann SM
- Subjects
- Adult, Humans, Male, Middle Aged, Brain Chemistry, Gastrointestinal Hormones analysis, Hypothalamo-Hypophyseal System analysis, Median Eminence analysis, Vasoactive Intestinal Peptide analysis
- Published
- 1978
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15. Evidence for an FSH-releasing factor in the posterior portion of the rat median eminence.
- Author
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Mizunuma H, Samson WK, Lumpkin MD, and McCann SM
- Subjects
- Animals, Dose-Response Relationship, Drug, Gonadotropin-Releasing Hormone pharmacology, In Vitro Techniques, Luteinizing Hormone metabolism, Male, Rats, Rats, Inbred Strains, Tissue Distribution, Follicle Stimulating Hormone metabolism, Gonadotropin-Releasing Hormone metabolism, Median Eminence metabolism
- Abstract
To test the hypothesis that an FSH-releasing factor might be contained within the posterior portion of the median eminence (ME), the anterior half of the ME (aME) and the posterior half of the ME (pME) were removed separately from the brains of adult male rats and extracted in 0.2 N acetic acid. LH and FSH-releasing activities of the extracts were measured in vitro by incubating 8 hemipituitaries from adult male rats for 6 h at a dose of 5 tissue equivalents and determining the radioimmunoassayable LH and FSH released into the medium. LH release induced by the aME extracts was significantly greater than that induced by the pME in both experiments, whereas there were no differences in FSH release between aME and pME extracts. A significant dose-related increase in FSH release was noted in this system when 1 and 2 ng of synthetic LHRH were tested which indicates that the assay was sensitive to different amounts of LHRH with regard to FSH-releasing action. The content of immunoreactive LHRH in the extracts was almost twice as high in the aME as in the pME. Therefore, the results indicate that the pME has greater FSH-releasing activity than can be accounted for by its content of LHRH. The additional FSH-releasing activity is presumably due to an FSH-releasing factor distinct from LHRH.
- Published
- 1983
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16. Effects of intraventricular injection of gastrin on release of LH, prolactin, TSH and GH in conscious ovariectomized rats.
- Author
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Vijayan E, Samson WK, and McCann SM
- Subjects
- Animals, Castration, Female, Gastrins administration & dosage, In Vitro Techniques, Injections, Intravenous, Injections, Intraventricular, Male, Radioimmunoassay, Rats, Gastrins pharmacology, Growth Hormone metabolism, Luteinizing Hormone metabolism, Prolactin metabolism, Thyrotropin metabolism
- Published
- 1978
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17. Differential effects of naloxone on basal and stress-induced release of ACTH and prolactin in the male rat.
- Author
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Xu RK and McCann SM
- Subjects
- Adrenocorticotropic Hormone blood, Animals, Dose-Response Relationship, Drug, Ether, Male, Prolactin blood, Radioimmunoassay, Rats, Rats, Inbred Strains, Restraint, Physical, Adrenocorticotropic Hormone metabolism, Naloxone pharmacology, Prolactin metabolism, Stress, Physiological physiopathology, Stress, Psychological physiopathology
- Abstract
The effect of i.v. injection of various doses of naloxone (NAL) on plasma adrenocorticotropin (ACTH) and prolactin (Prl) in conscious animals bearing an indwelling intrajugular catheter was assessed. The effects were evaluated in animals which were left undisturbed and in others subjected to either restraint or ether stress. The results revealed that the dose of 3 mg/kg of NAL significantly reduced basal Prl levels, whereas a dose of 6 mg/kg of NAL was required to block completely either ether or restraint stress-induced release of Prl. The behavior of ACTH contrasted with that of Prl. There was no effect whatsoever of the 3 mg/kg dose of NAL on either resting or stress-induced ACTH levels, whereas a 6 mg/kg or 12 mg/kg dose of NAL elevated resting ACTH levels and only partially attenuated the further elevation induced by stress in these animals. The results clearly indicate a NAL sensitive step in the control of resting and stress-induced Prl release but indicate that the control of resting and stress-induced release of ACTH is different in that the predominantly millimicron receptor blocker, NAL, can elevate ACTH at high doses and can only partially block the response to stress. In contrast to Prl where opioid peptide control is solely stimulatory, this control of ACTH secretion appears to have both stimulatory and inhibitory features.
- Published
- 1989
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18. Effects of substance P and neurotensin on growth hormone and thyrotropin release in vivo and in vitro.
- Author
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Vijayan E and McCann SM
- Subjects
- Animals, Castration, Female, Growth Hormone metabolism, In Vitro Techniques, Injections, Intravenous, Injections, Intraventricular, Neurotensin administration & dosage, Pituitary Gland, Anterior drug effects, Rats, Substance P administration & dosage, Thyrotropin metabolism, Growth Hormone blood, Neurotensin pharmacology, Substance P pharmacology, Thyrotropin blood
- Published
- 1980
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19. Presence and possible site of action of secretin in the rat pituitary and hypothalamus.
- Author
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Samson WK, Lumpkin MD, and McCann SM
- Subjects
- Animals, Dose-Response Relationship, Drug, Female, Hypothalamus analysis, Hypothalamus drug effects, Male, Pineal Gland physiology, Pituitary Gland, Anterior analysis, Pituitary Gland, Anterior drug effects, Prolactin metabolism, Prolactin pharmacology, Rats, Rats, Inbred Strains, Secretin analysis, Secretin pharmacology, Septum Pellucidum physiology, Vasoactive Intestinal Peptide physiology, Hypothalamus physiology, Pituitary Gland, Anterior physiology, Secretin physiology
- Abstract
Secretin-like immunoreactivity was detected in extracts of several rat brain structures by radioimmunoassay, most notably in the pituitary, hypothalamus, pineal and septum. Its localization to these structures suggested that it might play a role in neuroendocrine events similar to its structural homolog vasoactive intestinal peptide. Dose-related stimulations (MED, 10(-7) M) of prolactin (PRL) release were observed after incubation of synthetic secretin with dispersed, cultured pituitary cells from male and ovariectomized (OVX) female rats. In OVX females, i.v. infusion of a high dose of secretin (10 micrograms) resulted in a significant elevation of PRL levels. Doses of secretin as low as 0.1 micrograms when administered into the third cerebroventricle were capable of significantly inhibiting PRL release in both males and OVX females, suggesting an ultrashort-loop, negative feedback of secretin. Secretin can now be added to the growing list of putative PRL-releasing agents.
- Published
- 1984
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20. Effects of dopaminergic stimulant, amfonelic acid, on anterior pituitary hormone release in conscious rats.
- Author
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Vijayan E, German DC, and McCann SM
- Subjects
- Animals, Behavior, Animal drug effects, Castration, Estradiol pharmacology, Female, Nalidixic Acid analogs & derivatives, Ovary physiology, Progesterone pharmacology, Rats, Time Factors, Naphthyridines pharmacology, Pituitary Hormones, Anterior metabolism
- Published
- 1978
- Full Text
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21. Partial characterization of immunoreactive substance P in the rat pituitary gland.
- Author
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DePalatis LR, Khorram O, Ho RH, Negro-Vilar A, and McCann SM
- Subjects
- Amino Acid Sequence, Animals, Cattle, Gonadotropin-Releasing Hormone analysis, Hypothalamus, Immune Sera analysis, Male, Pituitary Gland, Anterior analysis, Pituitary Gland, Posterior analysis, Radioimmunoassay, Rats, Rats, Inbred Strains, Somatostatin analysis, Substance P immunology, Pituitary Gland analysis, Substance P analysis
- Abstract
Two distinct carboxy-terminus-directed anti-substance P (SP) sera (R-1C and R-6G) were used to characterize immunoreactive SP (I-SP) in acetic acid extracts of anterior pituitary (AP) and posterior pituitary (PP) glands of adult male rats. The tissue concentrations of I-SP measured by R-1C and R-6G were comparable. The contents of I-SP were 600-1150 pg/AP and 25-52 pg/PP. I-luteinizing hormone releasing hormone and I-somatostatin (I-SOM) were undetectable in AP extracts, but PP extracts contained the equivalents of 325-785 pg I-SOM/gland. Serial dilutions of AP and PP extracts produced displacement curves with both SP antisera that were parallel to the respective synthetic SP standard and hypothalamic extract displacement curves. Gel filtrations of AP and PP extracts on a Sephadex G-25 column produced I-SP peaks eluting in the same fractions as synthetic SP and hypothalamic I-SP. However, the AP I-SP profile also revealed a side peak migrating between the void volume and the major I-SP peak. Neither immunoreactive species in the AP extract were eliminated when eluted with 6.0 M guanidine HCl, a strong denaturing agent. In vitro incubation of paired anterior hemipituitaries for 30 min in the presence of a 56 mM K+ concentration resulted in a significant (p less than .0001), 25-fold increase in the release of I-SP into the incubation medium above the mean control value. Radiofrequency lesions placed in the median eminence-arcuate region of male rats caused a significant (p less than .001) reduction of I-SP in both the AP and PP. These reductions were inversely related to the plasma prolactin values. The elevation in plasma prolactin was taken as an index of completeness of lesions. We conclude that: 1) the rat pituitary contains I-SP as assessed by its immunologic and chromatographic behavior, 2) K+ depolarization is a potent stimulator of the release of AP I-SP in vitro, 3) the ME-arcuate region is important for the maintenance of pituitary I-SP levels in the rat.
- Published
- 1984
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22. Putative neurotransmitters involved in discharging gonadotropin-releasing neurohormones and the action of LH-releasing hormone on the CNS.
- Author
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McCann SM and Moss RL
- Subjects
- Animals, Brain metabolism, Catecholamines pharmacology, Central Nervous System drug effects, Central Nervous System metabolism, Female, Gonadotropins metabolism, Hypothalamus metabolism, Hypothalamus physiology, Norepinephrine metabolism, Norepinephrine pharmacology, Ovulation, Pituitary Gland, Anterior drug effects, Pituitary Gland, Posterior drug effects, Prolactin metabolism, Gonadotropin-Releasing Hormone pharmacology, Pituitary Gland metabolism, Pituitary Gland, Anterior metabolism, Pituitary Gland, Posterior metabolism, Pituitary Hormone-Releasing Hormones metabolism
- Published
- 1975
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23. Intrahypothalamic action of corticotrophin-releasing factor (CRF) to inhibit growth hormone and LH release in the rat.
- Author
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Ono N, Lumpkin MD, Samson WK, McDonald JK, and McCann SM
- Subjects
- Adrenocorticotropic Hormone metabolism, Animals, Castration, Corticotropin-Releasing Hormone administration & dosage, Dose-Response Relationship, Drug, Female, Injections, Intravenous, Injections, Intraventricular, Pituitary Gland, Anterior drug effects, Rats, Rats, Inbred Strains, Corticotropin-Releasing Hormone pharmacology, Growth Hormone blood, Luteinizing Hormone blood
- Abstract
The effects of intravenous or intraventricular injection of synthetic ovine corticotrophin-releasing factor (oCRF) on plasma levels of anterior pituitary hormones were studied in conscious, ovariectomized (OVX) female rats and compared with the actions of the peptide on dispersed anterior pituitary cells from OVX female rats incubated in the presence of CRF. Third ventricular injection of oCRF in freely moving rats caused a significant increase in plasma levels of ACTH in a dose-related manner with a minimal effective dose of less than 0.5 micrograms (0.1 nmol). The effect was observable at 5 min after injection and persisted for the 60 min duration of the experiment. In contrast, growth hormone levels were significantly depressed within 15 min with a minimal effective intraventricular dose of 0.5 micrograms. The suppression persisted for the duration of the experiment but there was no additional effect of the higher dose of 5 micrograms. Plasma LH levels were also lowered by the highest dose of 5 micrograms (1.0 nmol) of oCRF, with the first significant lowering at 30 min. Lower doses had no effect on plasma LH. Plasma TSH levels were not significantly altered. Control injections of the 0.9% NaCl diluent were without effect on the levels of any of the hormones. Intravenous injection of similar doses of oCRF had no effect on plasma levels of GH or LH. The ACTH-releasing action of the oCRF preparation was confirmed by in vitro incubation of the peptide with dispersed anterior pituitary cells for 2 h. A dose-related release of ACTH occurred in doses ranging from 0.1-10 nM, but there were no effects on the release of the other anterior pituitary hormones. The results suggest that oCRF may act within the hypothalamus to suppress the release of GH and to a lesser extent LH. The stimulation of ACTH release following intraventricular CRF is presumably related to its uptake by portal blood vessels with delivery to the pituitary and stimulation of the corticotrophs.
- Published
- 1984
- Full Text
- View/download PDF
24. Regulation of anterior pituitary and brain beta-adrenergic receptors by ovarian steroids.
- Author
-
Petrovic SL, McDonald JK, De Castro JC, Snyder GD, and McCann SM
- Subjects
- Animals, Estrus, Female, Luteinizing Hormone blood, Ovariectomy, Rats, Rats, Inbred Strains, Receptors, Adrenergic, beta physiology, Brain Chemistry, Gonadal Steroid Hormones pharmacology, Pituitary Gland, Anterior analysis, Receptors, Adrenergic, beta analysis
- Abstract
Ovariectomy of adult female rats (200-230g) resulted in an increase in beta-adrenergic receptors in the cerebral cortex, hypothalamus and anterior pituitary. The anterior pituitary had the largest overall increase as well as the most rapid increase in beta-adrenergic receptor density of the tissues examined. The increase in hypothalamic or cerebral cortical beta-adrenergic receptors became apparent only long after ovariectomy (7-14 days). Fourteen days after ovariectomy, the density of beta-adrenergic receptors was 79%, 40%, and 24% in excess of control values in crude membranes prepared from anterior pituitary, hypothalamus and cerebral cortex, respectively. Over the same interval, the plasma concentration of luteinizing hormone (LH) increased 28-fold, while the concentration of follicle-stimulating hormone (FSH) rose 5-fold compared to control levels. Estradiol replacement (20 micrograms/kg/day) in these animals for four days before sacrifice concomitantly reduced plasma levels of the gonadotropins as well as the density of beta-adrenergic receptors in both the anterior pituitary and the hypothalamus. Long-term steroid replacement during the fifth and sixth week after ovariectomy, with implants of estradiol and progesterone which released the steroids in approximately physiological concentrations, significantly reduced beta-adrenergic density in anterior pituitary, but not in the hypothalamic membranes. This treatment significantly reduced plasma LH, but not FSH. Beta-adrenergic receptor density was also found to fluctuate significantly during the 4-day estrous cycle. The highest values were found on proestrus, and the lowest on diestrus 1. These studies indicate that changes in plasma concentrations of gonadal steroids (e.g. during the estrous cycle) influence the density of beta-adrenergic receptors in tissues involved in the control and release of anterior pituitary gonadotropins.
- Published
- 1985
- Full Text
- View/download PDF
25. Role of arginine vasopressin in control of ACTH and LH release during stress.
- Author
-
Ono N, Bedran de Castro J, Khorram O, and McCann SM
- Subjects
- Adrenocorticotropic Hormone blood, Animals, Arginine Vasopressin immunology, Castration, Ether, Female, Growth Hormone blood, Immune Sera pharmacology, In Vitro Techniques, Luteinizing Hormone blood, Pituitary Gland, Anterior metabolism, Prolactin blood, Radioimmunoassay, Rats, Rats, Inbred Strains, Adrenocorticotropic Hormone metabolism, Arginine Vasopressin physiology, Luteinizing Hormone metabolism, Stress, Physiological physiopathology
- Abstract
To determine the role of arginine vasopressin (AVP) in stress-induced release of anterior pituitary hormones, AVP antiserum or normal rabbit serum (NRS) was micro-injected into the 3rd ventricle of freely-moving, ovariectomized (OVX) female rats. A single 3 microliter injection was given, and 24 hours later, the injection was repeated 30 min prior to application of ether stress for 1 min. Although AVP antiserum had no effect on basal plasma ACTH concentrations, the elevation of plasma ACTH induced by ether stress was lowered significantly. Plasma LH tended to increase following ether stress but not significantly so; however, plasma LH following stress was significantly lower in the AVP antiserum-treated group than in the group pre-treated with NRS. Ether stress lowered plasma growth hormone (GH) levels and this lowering was slightly but significantly antagonized by AVP antiserum. Ether stress also elevated plasma prolactin (Prl) levels but these changes were not significantly modified by the antiserum. To evaluate any direct action of AVP on pituitary hormone secretion, the peptide was incubated with dispersed anterior pituitary cells for 2 hours. A dose-related release of ACTH occurred in doses ranging from 10 ng (10 p mole)-10 micrograms/tube, but there was no effect of AVP on release of LH. The release of other anterior pituitary hormones was also not affected except for a significant stimulation of TSH release at a high dose of AVP. The results indicate that AVP is involved in induction of ACTH and LH release during stress. The inhibitory action of the AVP antiserum on ACTH release may be mediated intrahypothalamically by blocking the stimulatory action of AVP on corticotropin-releasing factor (CRF) neurons and/or also in part by direct blockade of the stimulatory action of vasopressin on the pituitary. The effects of vasopressin on LH release are presumably brought about by blockade of a stimulatory action of AVP on the LHRH neuronal terminals.
- Published
- 1985
- Full Text
- View/download PDF
26. Inhibition of prolactin secretion by a direct effect of methysergide on the pituitary lactotrophs in the rat.
- Author
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Krulich L, Coppings RJ, McCann SM, and Mayfield MA
- Subjects
- Animals, Depression, Chemical, Female, Male, Median Eminence physiology, Methyltyrosines pharmacology, Pimozide pharmacology, Piribedil pharmacology, Pituitary Gland drug effects, Prolactin blood, Rats, Spiperone pharmacology, Thyrotropin blood, Time Factors, Methysergide pharmacology, Pituitary Gland metabolism, Prolactin metabolism
- Published
- 1978
- Full Text
- View/download PDF
27. Stimulation of prolactin secretion by morphine: role of the central serotonergic system.
- Author
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Koenig JI, Mayfield MA, McCann SM, and Krulich L
- Subjects
- Animals, Cyproheptadine pharmacology, Dihydroxytryptamines pharmacology, Dose-Response Relationship, Drug, Fenclonine pharmacology, Male, Metergoline pharmacology, Naloxone pharmacology, Prolactin blood, Rats, Serotonin physiology, Morphine pharmacology, Prolactin metabolism
- Published
- 1979
- Full Text
- View/download PDF
28. Dopamine and norepinephrine stimulate somatostatin release by median eminence fragments in vitro.
- Author
-
Negro-Vilar A, Ojeda SR, Arimura A, and McCann SM
- Subjects
- Animals, Dopamine Antagonists, In Vitro Techniques, Male, Median Eminence metabolism, Norepinephrine antagonists & inhibitors, Phentolamine pharmacology, Pimozide pharmacology, Rats, Dopamine pharmacology, Hypothalamo-Hypophyseal System drug effects, Median Eminence drug effects, Norepinephrine pharmacology, Somatostatin metabolism
- Published
- 1978
- Full Text
- View/download PDF
29. Releasing hormones and sexual behavior.
- Author
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Moss RL, McCann SM, and Dudley CA
- Subjects
- Adrenalectomy, Animals, Castration, Dose-Response Relationship, Drug, Female, Gonadal Steroid Hormones pharmacology, Gonadotropins, Pituitary pharmacology, Male, Posture, Rats, Gonadotropin-Releasing Hormone pharmacology, Sexual Behavior, Animal drug effects
- Published
- 1975
- Full Text
- View/download PDF
30. Concomitant inhibition of pulsatile luteinizing hormone (LH) and stimulation of prolactin release by prostacyclin (PGI2) in ovariectomized (OVX) conscious rats.
- Author
-
Ottlecz A and McCann SM
- Subjects
- 6-Ketoprostaglandin F1 alpha administration & dosage, 6-Ketoprostaglandin F1 alpha pharmacology, Animals, Cerebral Ventricles drug effects, Epoprostenol administration & dosage, Female, Injections, Intraventricular, Kinetics, Luteinizing Hormone blood, Prolactin blood, Rats, Rats, Inbred Strains, Cerebral Ventricles physiology, Epoprostenol pharmacology, Luteinizing Hormone metabolism, Ovariectomy, Prolactin metabolism
- Abstract
Prostacyclin (PGI2) or its stable metabolite, 6-keto-PGF1 alpha (1-5 micrograms) in 2.5 microliter 0.05 M phosphate buffer (pH 7.4), was injected into the third ventricle (3 V) of ovariectomized (OVX), freely moving rats. Control animals received 2.5 microliter of buffer. In the initial experiments a control blood sample was taken and then the PGI2 was injected and frequent samples taken thereafter. With this protocol injection of 2 micrograms of PGI2 produced a significant decrease in mean plasma LH only at 60 min after its injection (p less than .05), while the higher dose (5 micrograms) decreased plasma LH concentrations at 30 and 60 min (p less than .01 and p less than .001, respectively). In subsequent experiments, blood was removed from indwelling external jugular vein cannulae every 5-6 min during 2 hours and plasma LH and PRL levels were determined by radioimmunoassay. LH pulses were monitored and several parameters of LH pulsation were calculated during the hour before and after injection of phosphate buffer, PGI2 or 6-keto-PGF1 alpha. Intraventricular injection of phosphate buffer failed to modify the characteristic pulsatile release of LH and did not alter plasma PRL levels. The amplitude of LH pulses was significantly reduced by PGI2 and the inhibitory effect was dose-related. Even a dose of 1 microgram produced a significant reduction in pulse height and the response was graded with maximal reduction occurring with the 5 microgram dose which essentially abolished the LH pulses. Following the microinjection of 6-keto-PGF1 alpha, no significant changes were observed in plasma LH values and the pulses of the hormone. Five micrograms PGI2 considerably elevated plasma PRL values during the 20-25 min following its 3V injection, whereas the same dose of 6-keto-PGF1 alpha produced only a very slight stimulatory effect. Since PGI2 had no effect to alter LH release by cultured pituitary cells in vitro, it is concluded that PGI2 can act on structures near the 3V to inhibit pulsatile release of LHRH.
- Published
- 1988
- Full Text
- View/download PDF
31. Testosterone control of brain and anterior pituitary beta-adrenergic receptors.
- Author
-
Petrovic SL, McDonald JK, Snyder GD, and McCann SM
- Subjects
- Animals, Binding, Competitive, Castration, Follicle Stimulating Hormone blood, Hypothalamus metabolism, Luteinizing Hormone blood, Male, Prolactin blood, Rats, Rats, Inbred Strains, Receptors, Adrenergic, beta classification, Receptors, Adrenergic, beta drug effects, Testosterone pharmacology, Brain metabolism, Pituitary Gland, Anterior metabolism, Receptors, Adrenergic, beta metabolism, Testosterone physiology
- Abstract
Orchidectomy of adult albino rats resulted in a quick, (approximately 70%) increase in the density of beta-adrenergic receptors in the anterior pituitary gland within the first day. There was a concurrent rapid increase in plasma levels of pituitary gonadotropins. The beta-receptor density continued to increase slowly for at least 16 days after castration, but it could be lowered significantly to the levels of sham-operated animals by treatment with testosterone (3 mg/kg/day) beginning on the fourth day after castration and continuing for 4 days. This treatment also completely reversed the elevation in plasma levels of luteinizing hormone (LH), and significantly reduced the circulating follicle-stimulating hormone (FSH) levels. Prolactin levels were not significantly altered by the treatments used in these studies. Most of the beta-adrenergic receptors induced by orchidectomy in the anterior pituitary were shown, using a beta 1-selective antagonist, practolol, or a beta 2-selective antagonist, IPS-339, to be of the beta 2-subtype. The density of the beta-adrenergic receptors in the cerebral cortex also increased significantly (10-24%) after castration, and returned to the levels of sham-operated animals following treatment with testosterone. No significant change in the density of the beta-adrenergic receptors in the hypothalamus resulted from either castration or testosterone replacement.
- Published
- 1984
- Full Text
- View/download PDF
32. Involvement of catecholamines in feedback mechanisms.
- Author
-
Kalra P and McCann SM
- Subjects
- Animals, Estradiol pharmacology, Feedback, Progesterone pharmacology, Rats, Stimulation, Chemical, Catecholamines physiology
- Published
- 1973
- Full Text
- View/download PDF
33. The effect of adrenalectomy on the blood pressure of rats subjected to auditory stimulation.
- Author
-
McCANN SM and ROTHBALLER AB
- Subjects
- Animals, Rats, Acoustic Stimulation, Adrenalectomy, Blood Pressure
- Published
- 1948
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