Site-Specific Opioid Receptor Blockade Allows Prepubertal Guinea Pigs to Display Progesterone-Facilitated Lordosis

The central endogenous opioid system is involved in the modulation of interleukin (IL)-6, an inflammatory cytokine that plays a major role in the acute phase response. The present study evaluates whether specific opioid receptor subtypes are selectively involved in this immunomodulatory action. IL-1 beta was administered either intracerebroventricularly or intraperitoneally at the dose of 400 ng to rats pretreated with the mu-antagonist beta-funaltrexamine, the delta-antagonist naltrindole, or the kappa-antagonist nor-binaltorphimine, each at the doses of 1, 10, and 100 micrograms/rat intracerebroventricularly. Serum IL-6 levels were measured 2 h later. The results show that mu-receptor blockade increases, whereas delta-receptor blockade decreases IL-6 induction, suggesting that the fine tuning exerted by opioids on the immune system may be achieved through a balance of opposing effects. Moreover the three antagonists affect IL-6 induction by central and peripheral IL-1 beta with a similar pattern, indicating that the brain endogenous opioid system plays a general role in the regulation of this cytokine.

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Opioid Receptor Blockade Eliminates Mood Effects of Aerobic Gymnastics

International Journal of Sports Medicine ◽

10.1055/s-2002-23168 ◽

2002 ◽

Vol 23 (3) ◽

pp. 155-157 ◽

Cited By ~ 23

Author(s):

A. Järvekülg ◽

A. Viru

Keyword(s):

Opioid Receptor ◽

Receptor Blockade ◽

Mood Effects

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Synergistic Interaction between Opioid Receptor Blockade and Alpha-Adrenergic Stimulation on Luteinizing Hormone-Releasing Hormone (LHRH) Secretion in vitro

Neuroendocrinology ◽

10.1159/000125328 ◽

1990 ◽

Vol 51 (2) ◽

pp. 131-138 ◽

Cited By ~ 10

Author(s):

Richard W. Clough ◽

Gloria E. Hoffman ◽

Celia D. Sladek

Keyword(s):

Luteinizing Hormone ◽

Opioid Receptor ◽

Synergistic Interaction ◽

Receptor Blockade ◽

Adrenergic Stimulation ◽

Luteinizing Hormone Releasing Hormone ◽

Releasing Hormone

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Normalization of hyperinsulinemia by chronic opioid receptor blockade in hyperandrogenemic women

Fertility and Sterility ◽

10.1016/j.fertnstert.2006.01.039 ◽

2006 ◽

Vol 86 (3) ◽

pp. 651-657 ◽

Cited By ~ 17

Author(s):

Dijana Hadžiomerović ◽

Bernhard Rabenbauer ◽

Ludwig Wildt

Keyword(s):

Opioid Receptor ◽

Receptor Blockade

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Panicolytic-like effect of µ1-opioid receptor blockade in the inferior colliculus of prey threatened by Crotalus durissus terrificus pit vipers

Journal of Psychopharmacology ◽

10.1177/0269881118822078 ◽

2019 ◽

Vol 33 (5) ◽

pp. 577-588 ◽

Cited By ~ 6

Author(s):

Fabrício Calvo ◽

Rafael Carvalho Almada ◽

Tayllon dos Anjos-Garcia ◽

Luiz Luciano Falconi- Sobrinho ◽

Tatiana Paschoalin-Maurin ◽

...

Keyword(s):

Inferior Colliculus ◽

Opioid Receptor ◽

Panic Attack ◽

Opioid Peptide ◽

Receptor Blockade ◽

Endogenous Opioid ◽

Endogenous Opioid Peptide ◽

Crotalus Durissus Terrificus ◽

Experimental Apparatus ◽

Crotalus Durissus

Background: The endogenous opioid peptide system has been implicated in the neural modulation of fear and anxiety organised by the dorsal midbrain. Furthermore, previous results indicate a fundamental role played by inferior colliculus (IC) opioid mechanisms during the expression of defensive behaviours, but the involvement of the IC µ1-opioid receptor in the modulation of anxiety- and panic attack-related behaviours remains unclear. Using a prey-versus-snake confrontation paradigm, we sought to investigate the effects of µ1-opioid receptor blockade in the IC on the defensive behaviour displayed by rats in a dangerous situation. Methods: Specific pathogen-free Wistar rats were treated with microinjection of the selective µ1-opioid receptor antagonist naloxonazine into the IC at different concentrations (1.0, 3.0 and 5.0 µg/0.2 µL) and then confronted with rattlesnakes ( Crotalus durissus terrificus). The defensive behavioural repertoire, such as defensive attention, flat back approach (FBA), startle, defensive immobility, escape or active avoidance, displayed by rats either during the confrontations with wild snakes or during re-exposure to the experimental context without the predator was analysed. Results: The blockade of µ1-opioid receptors in the IC decreased the expression of both anxiety-related behaviours (defensive attention, FBA) and panic attack-related responses (startle, defensive immobility and escape) during the confrontation with rattlesnakes. A significant decrease in defensive attention was also recorded during re-exposure of the prey to the experimental apparatus context without the predator. Conclusion: Taken together, these results suggest that a decrease in µ1-opioid receptor signalling activity within the IC modulates anxiety- and panic attack-related behaviours in dangerous environments.

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The effects of feeding suet-enriched chow on site-specific differences in the composition of triacylglycerol fatty acids in adipose tissue and its interactionsin vitrowith lymphoid cells

British Journal Of Nutrition ◽

10.1079/bjn19970061 ◽

1997 ◽

Vol 77 (4) ◽

pp. 621-643 ◽

Cited By ~ 25

Author(s):

Christine A. Mattacks ◽

Caroline M. Pond

Keyword(s):

Fatty Acids ◽

Adipose Tissue ◽

Fatty Acid Composition ◽

Fatty Acid ◽

Lymph Nodes ◽

Acid Composition ◽

Guinea Pigs ◽

Saturated Fatty Acids ◽

Lymphoid Cells ◽

Site Specific

The effects of diet on the composition and properties of adipose tissue in relation to lymph nodes were studied in adult guinea-pigs. The proportions of monoenoic triacylglycerol fatty acids were constant in all sites in adipose tissue of similarly fed guinea-pigs, but were substantially greater in samples from guinea-pigs fed on suet-enriched chow. Triacylglycerols in adipose tissue from near nodes contained significantly fewer saturated fatty acids, and significantly more 18:2n−6 and 18:3n−3 than those in samples from sites remote from nodes within the same depot. Depots that interact most strongly with lymphoid cellsin vitrohad the largest and most consistent within-depot differences. The gradients of triacylgiycerol fatty acid composition with distance from lymph nodes in two small intermuscular depots were similar in guinea-pigs fed on plain or suet-enriched chow. These findings are consistent with the hypothesis that adipose tissue around lymph nodes is specialized for local interactions with the lymphoid cells therein, and help to explain the variability of serial or duplicate measurements of adipose tissue composition. When cultured alone, lipopolysaccharide-stimulated lymph node lymphoid cells from suet-fed guinea-pigs incorporated as much labelled thymidine as the controls. Adipose tissue explants from suet-fed guinea-pigs inhibited lymphocyte proliferation much less than those of the controls, although the site-specific differences were similar. The pattern of site-specific differences in glycerol released from explants incubated alone was generally similar for both dietary groups, but except in the popliteal depot, the increases following co-culturing with lymphoid cells were smaller for samples from suet-fed guinea-pigs. These experiments show that minor changes in the fatty acid composition of the diet can substantially alter the interactions between adipose tissue and lymphoid cells.

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