scholarly journals Effects of opioid peptides administered in conscious rats on the changes in blood adrenaline leves caused by immobilization stress.

1989 ◽  
Vol 50 (3) ◽  
pp. 354-356 ◽  
Author(s):  
Mikio NAKAMURA ◽  
Kunie KAMATA ◽  
Hakubun INOUE ◽  
Minoru INABA
Keyword(s):  
Opioid Peptides ◽  
Immobilization Stress ◽  
Conscious Rats

Influence of opioid peptides on release from vasopressin and oxytocin neurones of the hypothalamoneurohypophyseal system: effects of naloxone in the conscious rat

1990 ◽  
Vol 68 (5) ◽  
pp. 568-574 ◽  
Author(s):  
Savio W. T. Cheng ◽  
Edward F. O'Connor ◽  
William G. North
Keyword(s):  
Plasma Concentration ◽  
Opioid Peptides ◽  
Plasma Concentrations ◽  
Plasma Osmolality ◽  
Plasma Sodium ◽  
Endogenous Opioid ◽  
Salt Loading ◽  
Conscious Rats ◽  
Basal Plasma ◽  
Acute And Chronic Treatments

We examined the effects of acute and chronic treatments with naloxone on release of vasopressin and oxytocin from the hypothalamoneurohypophyseal system (HNS) in conscious, chronically instrumented Long–Evans rats. Plasma concentrations of vasopressin-associated neurophysin and oxytocin-associated neurophysin were evaluated before and during an intravenous infusion of 18% saline at 100 μL∙kg−1 body weight∙min−1 for 60 min. Acute treatment with naloxone (2.75 μmol/kg, intravenous) did not measurably alter basal plasma osmolality or vasopressin-associated neurophysin concentration, but it caused a three-fold rise in basal plasma oxytocin-associated neurophysin concentration (16 ± 2 to 46 ± 3 fmol/mL, p < 0.005). Chronic treatment with naloxone (13.75 μmol/day, subcutaneous pellets) increased plasma osmolality (292 ± 1 to 300 ± 2 mosmol/kg H2O, p < 0.01) by day 5, but it had no measurable effects on basal vasopressin- or oxytocin-associated neurophysin concentration. There were also no significant differences in plasma sodium concentration (144.8 ± 1.1 vs. 142.2 ± 1.4 mequiv./L) under both conditions. Acute and chronic treatments with naloxone accompanied by salt loading produced a five- and four-fold decrease in the rates that plasma concentration of vasopressin-associated neurophysin changed with plasma osmolality, compared with untreated salt-loaded control rats. For oxytocin secretion from the HNS, both treatments accompanied by salt loading substantially decreased the threshold for changes in relation to plasma osmolality; the rise in plasma concentration of oxytocin-associated neurophysin was similar at all levels of hyperosmotic stimulation. A strongly correlated relationship between plasma oxytocin-associated neurophysin and plasma osmolality (r = 0.739) found for control animals became poorly correlated following treatments (acute, r = 0.173; chronic, r = −0.079). Our results suggest that in conscious rats, endogenous opioid peptides enhance the secretion of vasopressin from neurones of the HNS in response to hyperosmotic stimulation but inhibit both basal and stimulated release of oxytocin.Key words: naloxone, vasopressin, oxytocin, neurophysin, conscious rats.

Involvement of Alpha-Adrenergic Mechanisms in Growth Hormone Release Induced by Opioid Peptides in Conscious Rats

1981 ◽  
Vol 33 (3) ◽  
pp. 129-135 ◽  
Author(s):  
Hideki Katakami ◽  
Yuzuru Kato ◽  
Norio Matsushita ◽  
Seiji Hiroto ◽  
Akira Shimatsu ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Opioid Peptides ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Adrenergic Mechanisms ◽  
Conscious Rats

Effects of Naloxone on Vasopressin Secretion in Conscious Rats: Evidence for Inhibitory Role of Endogenous Opioid Peptides in Vasopressin Secretion*

Endocrinology ◽  
1989 ◽  
Vol 125 (2) ◽  
pp. 785-790 ◽  
Author(s):  
TAKAYUKI YAMADA ◽  
KAZUWA NAKAO ◽  
HIROSHI ITOH ◽  
GOTARO SHIRAKAMI ◽  
AKIRA SUGAWARA ◽  
...  
Keyword(s):  
Opioid Peptides ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Conscious Rats ◽  
Inhibitory Role ◽  
Vasopressin Secretion

Alleviation of pain and depression by specific neural transplants: Fine structural correlates

1992 ◽  
Vol 50 (2) ◽  
pp. 1066-1067
Author(s):  
George D. Pappas ◽  
Jacqueline Sagen
Keyword(s):  
Opioid Peptides ◽  
Chromaffin Cells ◽  
Pain Sensitivity ◽  
Opioid Peptide ◽  
Local Source ◽  
Pain Models ◽  
Neural Transplants ◽  
Adrenergic Antagonists ◽  
Csf Levels ◽  
Donor Source

We have been interested in the use of neural transplants mainly as a local source of neuroactive substances, rather than as a replacement for damaged neural circuities. In particular, we have been exploring the possibilities of reducing pain by transplants of opioid peptide producing cells, and reducing depression by transplants of monoamine-producing cells. For the past several years, work in our laboratory has demonstrated in both acute and chronic pain models that transplantation of adrenal medullary tissue or isolated chromaffin cells into CNS pain modulatory regions can reduce pain sensitivity in rodents. Chromaffin cells were chosen as donor source since they produce high levels of both opioid peptides and catecholamines, substances which independently, and probably synergistically, reduce pain sensitivity when injected locally into the spinal cord. The analgesia produced by these transplants most likely results from the release of both opioid peptides and catecholamines, since it can be blocked or attenuated by opiate or adrenergic antagonists, respectively. Furthermore, CSF levels of met-enkephalin and catecholamines are increased by the transplants.

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