Circadian rhythm of histamine release from the hypothalamus of freely moving rats.
Using an in vivo microdialysis technique coupled with HPLC-fluorometry, the release of neuronal histamine from the anterior hypothalamic area was monitored continuously in conscious, freely moving rats under a 12:12 h light:dark cycle. Spontaneous locomotor activity of the rats was measured simultaneously using a locomotor activity counter. Histamine release gradually increased in the second half of the light period (1400-2000) and the average histamine release during the dark period (2000-0800, 0.20 +/- 0.02 pmol/30 min) was significantly higher than that during the light period (0.12 +/- 0.01 pmol/30 min). This clear circadian change in the release suggests that the central histaminergic system is related to the circadian rhythm of rats.
Mochizuki
T
T
Department of Pharmacology II, Faculty of Medicine, Osaka University, Japan.
Yamatodani
A
A
Okakura
K
K
Horii
A
A
Inagaki
N
N
Wada
H
H
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D006632:Histamine / Q000378:metabolism*; D007032:Hypothalamus, Anterior / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000502:physiology*
D006632:Histamine