Possible involvement of orexin in the stress reaction in rats

Biochem Biophys Res Commun. 2000 Apr 2;270(1):318-23. doi: 10.1006/bbrc.2000.2412.


We examined whether corticotropin-releasing factor (CRF) was involved in orexin-induced grooming and face-washing behaviors, and whether orexin was involved in the stress reaction. Administration of alpha-helical CRF, CRF antagonist, alone had no behavioral effect, but it blocked the orexin-induced grooming and face-washing behaviors in rats. The level of corticosterone increased in a dose-dependent manner 15 min after icv injection of orexin, and it remained high for at least 60 min. In 2-month-old rats, 1 h of immobilization stress increased orexin mRNA levels, but not the melanin-concentrating hormone (MCH) mRNA, in the lateral hypothalamic area (LHA). In 6-month-old rats, 30 min of cold stress increased the expression of orexin mRNA in the LHA. Unlike in the 2-month-old rats, immobilization stress did not change orexin mRNA expression in 6-month-old rats. These results suggest that CRF is involved in orexin-induced behaviors, and that orexin may play an important role in some stress reactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Appetitive Behavior / drug effects*
  • Carrier Proteins / biosynthesis
  • Carrier Proteins / genetics
  • Carrier Proteins / pharmacology*
  • Cold Temperature
  • Corticosterone / blood
  • Corticotropin-Releasing Hormone / antagonists & inhibitors
  • Corticotropin-Releasing Hormone / biosynthesis
  • Corticotropin-Releasing Hormone / pharmacology*
  • Hypothalamic Area, Lateral / metabolism*
  • Hypothalamic Hormones / biosynthesis
  • Immobilization
  • Injections, Intraventricular
  • Intracellular Signaling Peptides and Proteins*
  • Male
  • Melanins / biosynthesis
  • Neuropeptides / biosynthesis
  • Neuropeptides / genetics
  • Neuropeptides / pharmacology*
  • Orexins
  • Pituitary Hormones / biosynthesis
  • RNA, Messenger / analysis
  • Rats
  • Rats, Sprague-Dawley
  • Rats, Wistar
  • Stress, Physiological / metabolism*


  • Carrier Proteins
  • Hypothalamic Hormones
  • Intracellular Signaling Peptides and Proteins
  • Melanins
  • Neuropeptides
  • Orexins
  • Pituitary Hormones
  • RNA, Messenger
  • melanin-concentrating hormone
  • Corticotropin-Releasing Hormone
  • Corticosterone