Phase advances of circadian rhythms in somatostatin depleted rats: effects of cysteamine on rhythms of locomotor activity and electrical discharge of the suprachiasmatic nucleus

C. Fukuhara, S. I T Inouye, K. Aoki, T. Hamada, Shigenobu Shibata, S. Watanabe

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16 Citations (Scopus)


Somatostatin is synthesized in the suprachiasmatic nucleus (SCN), a circadian pacemaker in mammals. To explore the functional significance of somatostatin in the circadian system, we examined rhythms of rat locomotor activity and electrical firing rate of SCN neurons in the brain slice after temporal depletion of somatostatin levels in the SCN. Intraperitoneal administration of cysteamine (200 mg/kg), a somatostatin depletor, significantly reduced somatostatin level in the in vivo SCN 5 min after injection and kept low level as long as 3 to 4 days. This administration, on the other hand, induced significant phase advances of about 51 min in the subsequent free-running rhythm of locomotor activity of the rat. A marked phase advance in the circadian rhythm of firing rate in the SCN was also observed after administration of cysteamine in coronal hypothalamic slices. These persistent phase shifts after administration of a somatostatin depletor may suggest that the change of somatostatin level in the SCN have a feedback influence on the circadian pacemaker.

Original languageEnglish
Pages (from-to)677-685
Number of pages9
JournalJournal of Comparative Physiology A
Issue number6
Publication statusPublished - 1994 Dec
Externally publishedYes



  • Brain slice
  • Circadian rhythm
  • Cysteamine
  • Somatostatin
  • Suprachiasmatic nucleus

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Neuroscience(all)
  • Physiology (medical)
  • Physiology
  • Animal Science and Zoology

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