Circadian rhythm of cell proliferation in the telencephalic ventricular zone: effect of in utero exposure to ethanol.
The neocortical ventricular zone is composed of a desynchronized population of proliferating cells. These cells give rise to neurons in the infragranular laminae of neocortex. The present study documents a diurnal rhythmicity of cell proliferation in the ventricular zone and examines the effects of ethanol on this biological clock. Pregnant rats were fed one of 3 diets. They were provided an ethanol-containing (6.7% v/v) liquid diet ad libitum between gestational day (G) 6 and G18, pair-fed an isocaloric liquid control diet, or fed chow and water. Throughout the experiments, the rats were fed either at 08.00 h (E.S.T) or at 17.00 h (lights on 06.00 to 18.00 h). Rats were given a single injection of bromodeoxyuridine (BrdU) on G17 at one point during a 24 h period (03.00, 06.00, 09.00 h, etc.). The fraction of ventricular cells that incorporated the BrdU was determined using quantitative immunohistochemical methods. Pair-fed control rats (fed at 08.00 or 17.00 h) consumed their food within 4 h of presentation. The ratio of cells passing through the S-phase of the cell cycle changed diurnally; the ratio was highest during the day (0.52 +/- 0.01 at 12.00 h) and lowest during the night (0.40 +/- 0.02 at 03.00 h). In contrast, the ethanol-fed rats grazed on their food throughout the dark cycle regardless of when the food was presented. The mean peak blood ethanol concentration was 142 +/- 13 mg/dl during the dark phase and less than 25 mg/dl during the light phase. Prenatal exposure to ethanol eliminates the fetal circadian rhythm in cell proliferation (mean labeling index of 0.45 +/- 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)
Miller
M W
MW
Research Service, Veterans Affairs Medical Center, Iowa City, IA 52242.
D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002455:Cell Division / Q000502:physiology*; D002552:Cerebral Ventricles / Q000166:cytology / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004435:Eating / Q000187:drug effects; D000431:Ethanol / Q000633:toxicity*; D005260:Female; D007150:Immunohistochemistry; D011247:Pregnancy; D051381:Rats; D013687:Telencephalon / Q000166:cytology / Q000502:physiology*
D000431:Ethanol; D001973:Bromodeoxyuridine