Abstract
Objective We aimed to assess the effects of neuroserpin and its combination with hypothermia
on hypoxic-ischemic (HI) brain injury in neonatal rats. Neuroserpin is an axon-secreted
serine protease inhibitor and is important for brain development, neuronal survival,
and synaptic plasticity.
Study Design Male Wistar–Albino rats on postnatal day 7 (P7) were randomly divided into five groups:
sham group (n = 10), (HI; n = 10), hypoxic-ischemic hypothermia (HIH; n = 10), hypoxic-ischemic neuroserpin (HIN; n = 10), and hypoxic-ischemic neuroserpin-hypothermia (HINH; n = 10). The P7 rat brain's maturation is similar to a late preterm human brain at
34 to 36 weeks of gestation. HI was induced in rats on P7 as previously described.
A single dose of 0.2 µM neuroserpin (HINH and HIN) or an equivalent volume of phosphate-buffered
saline (sham, HIH, and HI) was administered intraventricularly by a Hamilton syringe
immediately after hypoxia. In the follow-up, pups were subjected to systemic hypothermia
or normothermia for 2 hours. Euthanasia was performed for histopathological evaluation
on P10. Apoptosis was detected by caspase-3 activity and terminal deoxynucleotidyl
transferase-mediated dUTP nick end-labeling (TUNEL) staining and was counted in the
hippocampus.
Results In comparison to the HI group, the TUNEL-positive and caspase-3-positive neurons
in the sham, HIN, HIH, and HINH groups were considerably lower (13.4 ± 1.0 vs. 1.9 ± 0.9,
6.0 ± 0.9, 5.3 ± 1.6, and 4.0 ± 1.1; p < 0.001) and (13.5 ± 1.7 vs. 1.2 ± 0.7, 9.1 ± 2.7, 4.8 ± 1.0, and 3.9 ± 1.6; p < 0.001). HIN, HIH, and HINH, compared to the sham group, showed more TUNEL-positive
and caspase-3-positive neurons (6.0 ± 0.9, 5.3 ± 1.6, 4.0 ± 1.1 vs. 1.9 ± 0.9 and
9.1 ± 2.7, 4.8 ± 1.0, 3.9 ± 1.6 vs. 1.2 ± 0.7; p < 0.001). The HINH group (synergistic effect) had significantly fewer TUNEL-positive
neurons and caspase-3-positive neurons than the HIN group (4.0 ± 1.1 vs. 6.0 ± 0.9
and 3.9 ± 1.6 vs. 9.1 ± 2.7; p < 0.001).
Conclusion Our study showed that both neuroserpin alone and as an adjuvant treatment for hypothermia
may have a neuroprotective effect on brain injury.
Key Points
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Neuroserpin decreased brain injury.
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Neuroserpin showed a synergistic effect when used as an adjuvant treatment for hypothermia.
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The neuroprotective effect of neuroserpine was related to its antiapoptotic properties.
Keywords
neuroserpin - hypothermia - hypoxic-ischemic encephalopathy - rats
