Change of orphanin content in hypothalamus and peripheral blood of fetal rats with ischemia and hypoxia

Hang GU; Dian HU; Xinru HONG; Yong LIANG

ABSTRACT

BACKGROUND:

Orphanin (OFQ) is associated with ischemia/hypoxia,which may play an important role in the production and development of fetal distress and neonatal asphyxia.

OBJECTIVE:

To observe the change of OFQ content in hypothalamus and peripheral blood of intrauterine ischemia/hypoxia fetal rats and analyze the role of OFQ in the perinatal ischemia/hypoxia.

DESIGN:

Randomized controlled animal trial.

SETTING:

Department of Obstetrics and Gynecology, Changhai Hospital of the Second Military Medical University of Chinese PLA.MATERIALS The experiment was performed at the Department of Obstetrics and Gynecology, Changhai Hospital of the Secon d Military Medical University of Chinese PLA from May 2002 to September 2003. A total of 12 Wistar female rats, with the mean body mass of 260 g were selected and fed routinely [provided by the experiment animal center of this university, number of certificate scxk(Hu)2002/0006].

METHODS:

The 12 female rats were randomized into three groups control group, ischemia/hypoxia for 10 minutes group, ischemia/hypoxia for 20 minutes group with 4 rats in each group. Female rats in each group were pregnant. On day 21 of pregnancy, female rats in each group were cut the belly open, and the uterine vessels were incarcerated for 10 minutes in the ischemia/hypoxia for 10 minutes group with 21 fetal rats and 20 minutes in the ischemia/hypoxia for 20 minutes group with 17 fetal rats, respectively. Fetal rats were directly obtained from control group with 19 ones. None of fetal rats died. All the fetal rats received Apgar score and decapitation. The blood of trunk was collected and the whole brain was obtained. OFQ content in hypothalamus and peripheral blood was measured with radioimmunoassay.MAIN OUTCOME

MEASURES:

OFQ content in hypothalamus and peripheral blood of fetal rats in each group.

RESULTS:

Totally 57 rats were involved in the result analysis. ①The levels ofOFQ in hypothalamus and peripheral blood were (71±14) pg/g and (31±7) ng/L in ischemia/hypoxia for 10 minutes group, (114±21) pg/g and (58±11) ng/L in ischemia/hypoxia for 20 minutes group, (48±9) pg/g and (19±4) ng/L in the control group. Compared with the control group, the levels of OFQ in hypothalamus and peripheralblood increased in the ischemia/hypoxia for 10 minutes group and ischemia/hypoxia for 20 minutes group (P＜ 0.05, P ＜ 0.01), and it in ischemia/hypoxia for 10 minutes group was significantly higher than that in ischemia/hypoxia for 20 minutes group (P ＜ 0.05). ②The score of Apgar was lower in the two groups than in the control group (P ＜ 0.01 ), of which it was lower in the ischemia/hypoxia for 20minutes group than in the ischemia/hypoxia for 10 minutes group (P ＜ 0.05).

CONCLUSION:

The perinatal ischemia and hypoxia can induce the increase of OFQ content in hypothalamus and peripheral blood.