Levels of Dynorphin-(1–13) Immunoreactivity in Rat Neurointermediate Pituitaries Are Concomitantly Altered with Those of Leucine Enkephalin and Vasopressin in Response to Various Endocrine Manipulations

Höllt, Volker; Haarmann, I.; Seizinger, Bernd R.; Herz, A.

doi:10.1159/000123257

Cited by 111 publications

(18 citation statements)

References 8 publications

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“…If a change in axonal transport or release is indeed involved, altered metabo lism resulting from insulin deficiency may play a more prominent role than the lack of insulin per se. Increase in release from the NIL is a distinct possibility, at least for cholecystokinin, which is coreleased with vasopres sin [12] and fordynorphin, which is altered in content in the same way as vasopressin [35], because hyperosmolality in diabetes will un doubtedly lead to an increase in vasopressin release [33], If there is indeed an increase in the release of dynorphin and cholecystokinin from the NIL, the increased secretion of these neuropeptides and P-endorphin may stimu late insulin secretion from the 'residual' pan creatic islets in streptozotocin-treated rats, as a compensatory mechanism for the decrease in insulin secretion. Opioid peptides [36] and cholecystokinin [37] have been shown to be insulinotropic when administered peripher ally.…”

Section: Discussionmentioning

confidence: 99%

Pituitary Contents of Beta-Endorphin, Dynorphin, Substance P, Cholecystokinin and Somatostatin in Rats with Streptozotocin-lnduced Diabetes

Tang¹,

Wong²

1996

Neurosignals

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The effects of streptozotocin-induced diabetes on pituitary neuropeptides were studied. Substance P, dynorphin and β-endorphin in both pituitary lobes and cholecystokinin and somatostatin in the neurointermediate lobe () were measured 4 weeks after streptozotocin treatment in adult male rats. There were significant decreases of substance P levels in both the anterior lobe (AL) and , and of cholecystokinin, dynorphin and β-endorphin in the , whereas the dynorphin content in the AL increased, when values were expressed on a per-lobe basis. On a per-milligram-protein basis, however, only β-endorphin in the showed a significant decrease, while AL β-endorphin and dynorphin were increased. Correlated with these changes were a drastic decrease in the serum insulin level and a marked increase in serum glucose and corticosterone levels. All these changes were reversible with insulin treatment. It is suggested that the decrease in contents of neuropeptides demonstrated (except for β-endorphin) might be due to mechanisms other than a change in synthesis.

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Section: Discussionmentioning

confidence: 99%

Pituitary Contents of Beta-Endorphin, Dynorphin, Substance P, Cholecystokinin and Somatostatin in Rats with Streptozotocin-lnduced Diabetes

Tang¹,

Wong²

1996

Neurosignals

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“…Somehow, the anterior pituitary was not studied. Hollt et al [17], however, reported a decrease of leu-enkephalin in the neuro-intermediate lobe after adrenalectomy and an increase after dexamethasone treatment.…”

Section: Effect Of Corticosteroidsmentioning

confidence: 95%

Endocrine Control of Hypothalamic and Pituitary Met-Enkephalin and Beta-Endorphin Contents

Tang¹

1991

Neuroendocrinology

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This review summarizes the recent findings on the effects of endocrine manipulation on the hypothalamic and pituitary contents of met-enkephalin and β-endorphin. In the pituitary, gonadectomy decreases β-endorphin content in both the anterior lobe and neuro-intermediate lobe. Orchidectomy results in a decrease while ovariectomy leads to an increase in anterior lobe met-enkephalin contents. Adrenalectomy only leads to an increase in β-endorphin contents in the anterior pituitary lobe. Hypothyroidism induced by propylthiouracil treatment is accompanied by a decrease of β-endorphin in the neuro-intermediate lobe and a decrease in met-enkephalin in the anterior lobe while thyroidectomy entails a decrease in met-enkephalin in the anterior lobe only. Chemically induced diabetes mellitus results in a decrease in β-endorphin content in the hypothalamus and the neuro-intermediate lobe, and a reduction in met-enkephalin level in the anterior and neuro-intermediate lobes. All these changes are reversible with appropriate hormone treatments. These results indicate the importance of hormones in the regulation of the synthesis and/or release of the opioid peptides in the hypothalamus and the pituitary.

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“…The pituitary was divided into its AL and NIL component parts and the brain dissected to yield the hypothalamus, septum, midbrain and medulla/pons. Procedures for preparation of material for, and performance of, ra dioimmunoassays have been extensively described previously [13][14][15]22]. Owing to limitations in the amount of immunoreactive material in the septum and midbrain, it was impossible to deter mine the levels of each one of the peptides therein.…”

Section: Evaluation Of Levels O F Peptidesmentioning

confidence: 99%

“…Moreover, a variety of endocri nological manipulations have been documented to modu late, in parallel, neurointermediate lobe (NIL) concentra tions of ir-DYN and ir-VPin the rat [14].…”

mentioning

confidence: 99%

Contribution of the Supra-Optic Nucleus to Brain and Pituitary Pools of Immunoreactive Vasopressin and Particular Opioid Peptides, and the Interrelationships between These, in the Rat

Millan¹,

Millan²,

Herz³

1983

Neuroendocrinology

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Discrete, bilateral, radiofrequency destruction of the supra-optic nucleus resulted in a parallel fall in levels of immunoreactive (ir) dynorphin (DYN), ir-α-neoendorphin (α-NE) and ir-vasopressin (VP) in the hypothalamus, neuroin-termediate lobe (NIL) of the pituitary and septum of rats, whereas in the medulla/pons, midbrain and anterior lobe (AL), levels of these peptides were not significantly changed. The content of ir-β-endorphin (β-EP) was, in contrast, elevated in the hypothalamus and unchanged in the NIL and AL, while that of ir-metenkephalin (ME) was modified in neither the hypothalamus nor medulla/pons. As evaluated in lesioned and sham rats, collectively, hypothalamic levels of ir-DYN, ir-α-NE and ir-VP were positively correlated with their counterparts in the NIL but not, with the exception of ir-VP, with those in the AL. Ir-β-E did not show these relationships. Within the NIL and in the hypothalamus, levels of ir-DYN, ir-α-NE and ir-VP were positively correlated with each other and independent of those of ir-β-EP and ir-ME. In the AL and other brain tissues, however, only those of ir-DYN and ir-α-NE were positively and significantly correlated in contrast to ir-VP. Further, across all structures, although the ratio of levels of ir-α-NE to ir-DYN was quite constant, that of ir-VP to ir-DYN varied enormously. These data indicate that:(1) the supra-optic nucleus may contribute to NIL, hypothalamic and septal but not to AL, midbrain or medulla/pons pools of ir-VP, ir-DYN and ir-α-NE, and that it interacts with those of ir-β-EP in the hypothalamus. (2) in the NIL and hypothalamus, ir-DYN, ir-α-NE and ir-VP are, as compared to ir-β-EP and ir-ME, closely interrelated. (3) AL pools of DYN and ir-α-NE are closely coupled but, in contrast to NIL pools, not related to ir-VP and independent of the hypothalamus. (4) Extrahypothalamic brain pools of ir-DYN and ir-α-NE may be not related to ir-VP. The possible existence of ir-DYN and ir-α-NE independently or ir-VP in the AL and extrahypothalamic nervous tissue is discussed.

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Levels of Dynorphin-(1–13) Immunoreactivity in Rat Neurointermediate Pituitaries Are Concomitantly Altered with Those of Leucine Enkephalin and Vasopressin in Response to Various Endocrine Manipulations

Cited by 111 publications

References 8 publications

Pituitary Contents of Beta-Endorphin, Dynorphin, Substance P, Cholecystokinin and Somatostatin in Rats with Streptozotocin-lnduced Diabetes

Pituitary Contents of Beta-Endorphin, Dynorphin, Substance P, Cholecystokinin and Somatostatin in Rats with Streptozotocin-lnduced Diabetes

Endocrine Control of Hypothalamic and Pituitary Met-Enkephalin and Beta-Endorphin Contents

Contribution of the Supra-Optic Nucleus to Brain and Pituitary Pools of Immunoreactive Vasopressin and Particular Opioid Peptides, and the Interrelationships between These, in the Rat

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