Brain aromatase cytochrome P-450 messenger RNA levels and enzyme activity during prenatal and perinatal development in the rat.
Aromatase cytochrome P-450 (P-450AROM) enzyme activity catalyzes the conversion of androgens to estrogens in specific brain areas. During development local estrogen formation is thought to influence the sexual differentiation of neural structures (i.e. increase neurite growth and establish neural circuitry) and modulate reproductive functions. This study was undertaken to investigate the ontogeny of the (P-450AROM) enzyme and its messenger RNA (mRNA) in medial basal hypothalamic (MBH) and preoptic area (POA) tissue during late fetal and perinatal development of the rat. Aromatase activity in the MBH-POA was negligible before gestational day (GD) 16 (< 0.1 pmol/h/mg protein), increased over 10-fold at GD 17 and continued to increase (over 5-fold) to peak levels at GD 19 (> 5.0 pmol/h/mg protein), and then declined to low levels at GD 22 and 2 days post-birth (approximately 1 pmol/h/mg protein). The profile of P-450AROM mRNA in the MBH-POA tissue was characterized by a predominant 2.7 kilobase (kb) mRNA species, similar in size to the largest functional P-450AROM mRNA observed in adult rat ovarian tissue. At GD 15, the P-450AROM mRNA was undetectable; low but detectable levels were seen at GD 17, the abundance increased at later time points and remained at peak levels on GDs 18 through 20, decreased slightly by GD 22, and then declined further by 2 days post-birth. The developmental increase in P-450AROM mRNA levels correlated with the ascending pattern of enzyme activity before GD 19, but the marked decrease in enzyme activity seen after GD 19 was not accompanied by a corresponding decline in mRNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Lephart
E D
ED
Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas, Southwestern Medical Center, Dallas 75235.
Simpson
E R
ER
McPhaul
M J
MJ
Kilgore
M W
MW
Wilson
J D
JD
Ojeda
S R
SR
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism*; D001141:Aromatase / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D001921:Brain / Q000196:embryology / Q000201:enzymology / Q000502:physiology*; D015342:DNA Probes; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D007033:Hypothalamus, Middle / Q000201:enzymology / Q000378:metabolism; D008297:Male; D015335:Molecular Probes; D008969:Molecular Sequence Data; D011301:Preoptic Area / Q000201:enzymology / Q000378:metabolism; D015347:RNA Probes; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats
D015342:DNA Probes; D015335:Molecular Probes; D015347:RNA Probes; D012333:RNA, Messenger; D001141:Aromatase