The role of the retrochiasmatic area in the control of pineal metabolism.
The aim of the present investigation was to study the effect of neurotoxic ibotenic acid lesion of the retrochiasmatic area on the daily profile of pineal N-acetylserotonin and melatonin synthesis and on the pineal metabolic reactivity to nocturnal short-term retinal photostimulation. Groups of rats were killed 6 h after lights off either in the dark of immediately after being photostimulated for 1 or 15 min. Additionally, groups of rats were sacrificed at six different time points throughout the 24-hour light-dark cycle. The results suggested the presence of two functionally distinct territories in the retrochiasmatic area. The basal retrochiasmatic area, an area situated immediately ventral to the third ventricle, behind the suprachiasmatic nuclei and in front of the arcuate nucleus, is implicated in the nocturnal inhibitory process induced by short-term retinal photostimulation. The lateral retrochiasmatic area, which is situated immediately lateral to the anterior periventricular nucleus, below the anterior hypothalamic nucleus and in front of the ventromedial hypothalamic nucleus, is importantly involved in the control of the peak amplitude of the daily production of N-acetylserotonin and melatonin by the pineal gland.
Cipolla-Neto
J
J
Department of Physiology, Institute of Biomedical Sciences, University of São Paulo, Brazil. cipolla@fisio.icb1.usp.br
Skorupa
A L
AL
Ribeiro-Barbosa
E R
ER
Bartol
I
I
Mota
S R
SR
Afeche
S C
SC
Delagrange
P
P
Guardiola-Lemaitre
B
B
Canteras
N S
NS
D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007051:Ibotenic Acid / Q000494:pharmacology*; D008027:Light; D008297:Male; D008550:Melatonin / Q000096:biosynthesis; D010870:Pineal Gland / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000502:physiology; D012701:Serotonin / Q000031:analogs & derivatives / Q000096:biosynthesis; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology*