ABSTRACT
Hypoxic-ischemic encephalopathy (HIE) is a common cause of neonatal encephalopathy
and is one of the most important causes of neonatal death and disabilities, especially
those infants with moderate to severe encephalopathy. However, the pathogenesis of
HIE still remains unclear. The purpose of this study was to explore the dynamic changes
in plasma neuropeptide Y (NPY) and neurotensin (NT) as well as their role in regulating
cerebral hemodynamics in HIE patients. The plasma levels of NPY and NT in the umbilical
artery and peripheral blood on the first, third, and seventh days after birth in 40
term infants with HIE and 40 healthy controls were measured using radioimmunoassay.
On the first day of life, the blood samples were collected immediately when ultrasound
examinations were finished. The ultrasound transducer was placed on the temporal fontanelle
to detect the hemodynamic parameters of the middle cerebral artery, including peak
systolic flow velocity, end-diastolic flow velocity, time-average mean velocity, pulsatility
index, and resistance index (RI) in both groups were measured by pulse Doppler ultrasound
in the first day after birth. The relationship between RI and NPY or NT was analyzed
by linear regression analysis. NPY levels in umbilical blood ([mean ± standard deviation]
615.5 ± 130.7 ng/L) and first-day peripheral blood (355.9 ± 57.4 ng/L) in neonates
with HIE were significantly higher than those in normal newborns’ blood (199.1 ± 63.2
and 214.4 ± 58.0 ng/L, respectively; p < 0.01). NPY levels in HIE neonates then declined to control levels on the third
day after birth (p > 0.05). However, the levels of plasma NT in umbilical blood and peripheral blood
were much higher in the HIE group than those in normal newborns during the first week
(p < 0.01). The results of Doppler ultrasound examinations showed that cerebral blood
flow velocity significantly decreased, whereas RI increased markedly in HIE patients
compared with healthy controls (p < 0.01). Linear regression analysis revealed that the RI was positively correlated
with NPY levels (r = 0.614; p < 0.01) and negatively correlated with NT levels (r = -0.579; p < 0.01). The results of this study showed that there was a significant increase in
plasma NPY and NT levels in HIE patients and this was strongly related to the severity
of HIE, and the hemodynamic parameter RI was significantly correlated with NPY and
NT. Therefore, we believe that the dynamic changes in plasma NPY or NT levels participate
in the mechanisms of HIE by regulating cerebral hemodynamic changes after neonatal
asphyxia occurs.
KEYWORDS
Neonate - hypoxic-ischemic encephalopathy - neuropeptide Y - neurotensin - cerebral
hemodynamics
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