The Journal of Neuroscience, July 1, 2002, 22(13):5679-5686
Prostaglandin D Synthase in the Prenatal Ovine Brain and Effects
of Its Inhibition with Selenium Chloride on Fetal Sleep/Wake Activity
In Utero
Brenda
Lee,
Jonathan J.
Hirst, and
David W.
Walker
Department of Physiology, Monash University, Clayton, Melbourne,
Victoria, Australia, 3800
It has been proposed that prostaglandin (PG) D2 induces
physiological sleep in mammals by acting on sleep centers located in
the anterior hypothalamus. In fetal sheep, definitive
rapid-eye-movement and non-rapid-eye-movement sleep states
appear at ~125 d gestation (term is ~147 d). In adult animals, PGD
synthase (PGDS) (functionally and structurally homologous to
-trace
protein) is secreted into CSF with a circadian pattern, with the
highest concentrations present during sleep. In this study we show that
PGDS/
-trace protein is present in fetal sheep CSF at 125 and
135 d gestation but not at 90 d gestation.
SeCl4, a specific inhibitor of PGDS, was given to
unanesthetized fetal sheep (130-140 d gestation) by
intracerebroventricular infusion at a dose of 25, 100, 500, or 1000 pmol/min for 4 hr. Artificial CSF was infused in control experiments.
Arousal behavior, defined as the presence of nuchal muscle
electromyogram activity, electro-ocular activity, and breathing movements during low-amplitude electrocortical activity, increased from
3.8 ± 1 min/hr to 6.6 ± 0.5 and 7.0 ± 0.3 min/hr at
doses of 100 and 500 pmol/min, respectively
(p < 0.05). SeCl4 at 25 and
1000 pmol/min had no significant effect on arousal activity. Infusion
of PGD2 at 500 pmol/min intracerebroventricularly for 4 hr
decreased the incidence of arousal from 3.8 ± 0.5 min/hr to
0.7 ± 0.3 min/hr (p < 0.05). When 500 pmol/min PGD2 was infused immediately after a 4 hr infusion
of SeCl4 (500 pmol/min), the SeCl4-induced
increase in arousal behavior was abolished. Together, the presence of
PGDS/
-trace protein in fetal CSF in late gestation and the effects
of SeCl4 in increasing the incidence of arousal-like behavior suggest that PGD2 has a role in the induction and
maintenance of prenatal sleep.
Key words:
fetus; sleep/wake; arousal; prostaglandin D
synthase;
-trace protein; selenium chloride
Copyright © 2002 Society for Neuroscience 0270-6474/02/22135679-08$05.00/0