Abnormal development of the sinuatrial venous valve and posterior hindbrain may contribute to late fetal resorption of vitamin A-deficient rat embryos.
BACKGROUND
Normal embryonic development and survival in utero is dependent on an adequate supply of vitamin A. Embryos from vitamin A-deficient (VAD) pregnant rats fed an inadequate amount of all-trans retinoic acid (atRA; 12 microg per g of diet or approximately 230 microg per rat per day) exhibit severe developmental abnormalities of the anterior cardinal vein and hindbrain by embryonic day (E) 12.5 and die shortly thereafter.


METHODS
In the present study, we sought to determine whether supplementation of VAD-RA supported (12 microg per g of diet) pregnant rats with retinol (ROL) at the late-gastrula (presomite or rat E9.5) or early somite stages (E10.5), or provision of higher levels of atRA throughout this period could prevent abnormalities in the developing cardiovascular and nervous systems.


RESULTS
A newly described defect in the sinuatrial venus valve along with enlarged anterior cardinal veins and nervous system abnormalities and the later death of embryos are prevented by supplementing pregnant animals with ROL on the morning of E9.5. If ROL supplementation is delayed by 1 day (E10.5), most embryos are abnormal and die by E18.5. Supplementation of VAD rats with atRA (250 microg per g of diet) between E8.5 and E10.5 also prevents the cardiovascular and nervous system abnormalities and a significant number of these embryos survive to parturition. Thus, high levels of atRA can obviate the need for ROL between E9.5 and E10.5.


CONCLUSIONS
These results support an essential role for retinoid signaling between the late gastrula and early somite stages in the rat embryo for normal morphogenesis of the primitive heart tube and the posterior hindbrain. Further, these results suggest that embryonic death occurring at midgestation in the VAD rat may be linked to the abnormal development of one or both of these embryonic structures.
White
J C
JC
School of Pharmacy, University of Wisconsin, Madison, Wisconsin 53706-1508, USA.
Highland
M
M
Clagett-Dame
M
M
D000015:Abnormalities, Multiple / Q000209:etiology* / Q000517:prevention & control; D000821:Animal Feed; D000818:Animals; D003391:Cranial Nerves / Q000002:abnormalities / Q000196:embryology; D004224:Diterpenes; D004305:Dose-Response Relationship, Drug; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005260:Female; D005313:Fetal Death / Q000209:etiology / Q000517:prevention & control; D005318:Fetal Heart / Q000187:drug effects*; D005327:Fetal Resorption / Q000209:etiology* / Q000517:prevention & control; D005775:Gastrula / Q000187:drug effects; D005801:Genes, Homeobox; D005865:Gestational Age; D009024:Morphogenesis / Q000187:drug effects; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000503:physiopathology*; D051381:Rats; D000084562:Retinyl Esters; D012249:Rhombencephalon / Q000002:abnormalities* / Q000196:embryology; D014157:Transcription Factors / Q000235:genetics; D014212:Tretinoin / Q000008:administration & dosage / Q000627:therapeutic use*; D014680:Veins / Q000002:abnormalities* / Q000196:embryology; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D014802:Vitamin A Deficiency / Q000097:blood / Q000503:physiopathology*
D004224:Diterpenes; D000084562:Retinyl Esters; D014157:Transcription Factors; D014801:Vitamin A; C014794:retinol palmitate; D014212:Tretinoin