Rhythmic control of endocannabinoids in the rat pineal gland

Chronobiol Int. 2015;32(6):869-74. doi: 10.3109/07420528.2015.1041596. Epub 2015 Jun 10.


Endocannabinoids modulate neuroendocrine networks by directly targeting cannabinoid receptors. The time-hormone melatonin synchronizes these networks with external light condition and guarantees time-sensitive and ecologically well-adapted behaviors. Here, the endocannabinoid arachidonoyl ethanolamide (AEA) showed rhythmic changes in rat pineal glands with higher levels during the light-period and reduced amounts at the onset of darkness. Norepinephrine, the essential stimulus for nocturnal melatonin biosynthesis, acutely down-regulated AEA and other endocannabinoids in cultured pineal glands. These temporal dynamics suggest that AEA exerts time-dependent autocrine and/or paracrine functions within the pineal. Moreover, endocananbinoids may be released from the pineal into the CSF or blood stream.

Keywords: Arachidonoyl ethanolamide; cannabinoid receptor; diurnal rhythm; endocannabinoids; pineal gland.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonic Acids / chemistry
  • Circadian Rhythm*
  • Darkness
  • Endocannabinoids / chemistry
  • Endocannabinoids / physiology*
  • Light
  • Male
  • Organ Culture Techniques
  • Photoperiod
  • Pineal Gland / metabolism*
  • Pineal Gland / pathology
  • Polyunsaturated Alkamides / chemistry
  • Rats
  • Rats, Wistar


  • Arachidonic Acids
  • Endocannabinoids
  • Polyunsaturated Alkamides
  • anandamide