Orexins in the Regulation of the Hypothalamic-Pituitary-Adrenal Axis

@article{Spinazzi2006OrexinsIT,
  title={Orexins in the Regulation of the Hypothalamic-Pituitary-Adrenal Axis},
  author={Raffaella Spinazzi and Paola G. Andreis and Gian Paolo Rossi and Gastone Giovanni Nussdorfer},
  journal={Pharmacological Reviews},
  year={2006},
  volume={58},
  pages={46 - 57}
}
Orexin-A and orexin-B are hypothalamic peptides that act via two G protein-coupled receptors, named orexin type 1 and type 2 receptors (OX1-Rs and OX2-Rs). The most studied biological functions of orexins are the central control of feeding and sleep, but in the past few years findings that orexin system modulates the hypothalamic-pituitary-adrenal (HPA) axis, acting on both its central and peripheral branches, have accumulated. Orexins and their receptors are expressed in the hypothalamic… 

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References

SHOWING 1-10 OF 146 REFERENCES

Orexins stimulate corticosterone secretion of rat adrenocortical cells, through the activation of the adenylate cyclase-dependent signaling cascade

Orexins (hypocretins) and adrenal function.

Experimental data demonstrate a stimulatory effect of orexins on the secretion of adrenocortical steroids, mainly on glucocorticoids, and some results also suggest the regulation of catecholamine synthesis and release by orexin system.

Functions of the orexinergic/hypocretinergic system.

The present review focuses on the physiological properties of the cells that secrete or respond to orexins, which appear to be controlled by feeding- and sleep-related signals via a variety of neurotransmitters/hormones from the brain and other tissues.

Acute effects of orexins A and B on the rat pituitary-adrenocortical axis

Orexins A and B are hypothalamic peptides, which act through two receptor subtypes, called OXIR and OXZR, which are known to modulate the function of the pituitary-adrenocortical axis of the rat PAA and evidence indicates that OX,R binds both orexins, while OX zR is selective for orexin-B.

The Central Effects of Orexin‐A in the Hypothalamic‐Pituitary‐Adrenal Axis In Vivo and In Vitro in Male Rats

Results suggest that orexin‐A is involved in activation of the HPA axis, and that these effects could be mediated via the release of NPY.

Prolonged orexin administration stimulates steroid-hormone secretion, acting directly on the rat adrenal gland.

Findings indicate that orexins exert a marked direct chronic secretagogue action on adrenocortical cells, acting through both OX1R and OX2R.

Effects of Orexins on the Hypothalamic‐Pituitary‐Adrenal System

This study suggests that these appetite‐regulating peptides might activate the HPA system at a central level but neither orexin‐A nor orex in‐B appears to modulate directly the adrenal corticosterone release.

Orexin receptors are expressed in the adrenal medulla of the rat.

The results of the present study provide the first evidence showing that the adrenal medulla of the rat expresses orexin receptors, and thus appears to be a target tissue for orexins, which could open a new loop in which the central and autonomous nervous system may be involved in body weight homeostasis and sleep control.

Modulatory Effects of Orexins on the Function of Rat Pituitary-Adrenocortical Axis under Basal and Stressful Conditions

It is concluded that orexins evoke a transient activation of the rat pituitary-adrenocortical axis, acting on both its central and peripheral branch and exert a minor modulatory role on pituitaries' responses to stresses, their effects being dependent upon the type of stresses.

Food deprivation differentially modulates orexin receptor expression and signaling in rat hypothalamus and adrenal cortex.

The data indicate that food deprivation has differential effects on orexin receptor expression and their signaling characteristics at the hypothalamic and adrenocortical levels, and suggest orexins as potential metabolic regulators within the HPA axis both centrally and peripherally.
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