IGF-1 Protects Neurons in the Cortex and Subventricular Zone in a Periventricular Leucomalacia Model

Dexmedetomidine Stereotaxic Injection Alleviates Neuronal Loss Following Bilateral Common Carotid Artery Occlusion via Up-Regulation of BDNF Expression

BACKGROUND/AIM

Neurogenesis is an important process in the recovery from neurological damage caused by ischemic lesions. Endogenous neurogenesis is insufficient to restore neuronal damage following cerebral ischemia. Dexmedetomidine (DEX) exerts neuroprotective effects against cerebral ischemia and ischemia/reperfusion injury. DEX promotes neurogenesis, including neuronal proliferation and maturation in the hippocampus. In a previous study, we showed that early neurogenesis increased 3 days after bilateral common carotid artery occlusion (BCCAO). In this study, we investigated the effect of DEX on neurogenesis 3 days after BCCAO.

MATERIALS AND METHODS

Male Sprague-Dawley (SD) rats (7-8 weeks old) were used as a BCCAO model. Right and left common carotid arteries of the rats were occluded using 4-0 silk sutures. Two hours after surgery, an intracranial DEX injection was administered to rats that underwent surgery using a stereotaxic injector. Brains were obtained from control and BCCAO rats 3 days after surgery. Immunohistochemistry was performed on the cortex and dentate gyrus of the hippocampus using a NeuN antibody. Western blot was performed with HIF1α and brain-derived neurotrophic factor (BDNF) antibodies.

RESULTS

The number of mature neurons decreased 3 days after BCCAO, but DEX treatment alleviated neural loss in the parietal cortex and hippocampus. Up-regulation of BDNF was also observed after dexmedetomidine treatment.

CONCLUSION

Stereotaxic injection of dexmedetomidine alleviates neural loss following BCCAO by up-regulating BDNF expression.

Abnormal phosphorylation of protein tyrosine in neurodegenerative diseases

Neurodegenerative diseases, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and multiple sclerosis, are chronic disorders of the CNS that are characterized by progressive neuronal dysfunction. These diseases have diverse clinical and pathological features and their pathogenetic mechanisms are not yet fully understood. Currently, widely accepted hypotheses include the accumulation of misfolded proteins, oxidative stress from reactive oxygen species, mitochondrial dysfunction, DNA damage, neurotrophin dysfunction, and neuroinflammatory processes. In the CNS of patients with neurodegenerative diseases, a variety of abnormally phosphorylated proteins play important roles in pathological processes such as neuroinflammation and intracellular accumulation of β-amyloid plaques and tau. In recent years, the roles of abnormal tyrosine phosphorylation of intracellular signaling molecules regulated by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) in neurodegenerative diseases have attracted increasing attention. Here, we summarize the roles of signaling pathways related to protein tyrosine phosphorylation in the pathogenesis of neurodegenerative diseases and the progress of therapeutic studies targeting PTKs and PTPs that provide theoretical support for future studies on therapeutic strategies for these devastating and important neurodegenerative diseases.

Percentile-Based Reference Values of Umbilical Cord Blood Insulin-like Growth Factor 1 in Japanese Newborns

We aimed to create percentile-based reference values of the umbilical cord blood insulin-like growth factor-1 (IGF-1) levels in Japanese newborns, as these values have not yet been established. A total of 259 newborns were classified into four gestational-age-at-birth (GA) groups: extremely preterm (<28 weeks); early preterm (28−33 weeks); late preterm (34−36 weeks); and term (≥37 weeks). They were further subclassified as small-for-gestational-age (SGA) or non-SGA. The 10th, 25th, 50th, 75th, and 90th percentiles of the umbilical cord blood IGF-1 levels were calculated and compared between the groups by using reference values of 9, 18, 33, 52, and 71 ng/mL, respectively. In the extremely preterm group, the IGF-1 levels were significantly lower than those in the early preterm, late preterm, and term groups (13.5, 24.0, 44.5, and 47.5 ng/mL, respectively; p < 0.001). The umbilical cord blood IGF-1 levels in the SGA newborns were significantly lower than those in the non-SGA newborns in all subgroups. In multivariate analyses, the GA and birth weight standard deviation scores were independent determinant factors for the umbilical cord blood IGF-1 levels. Thus, we established percentile-based reference values of umbilical cord blood IGF-1 in Japanese newborns; these reference values can be applied on the basis of the extent of prematurity and the SGA status.