Intraperitoneal treatment with S100B enhances hippocampal neurogenesis in juvenile mice and after experimental brain injury.

BACKGROUND: Neurogenesis is documented in adult mammals including humans, is promoted by neurotrophic factors, and constitutes an innate repair mechanism following brain injury. The glial neurotrophic protein S100B is released following various types of brain injuries, enhances hippocampal neurogenesis and improves cognitive function following brain injury in rats when applied intrathecally. The present study was designed to elucidate whether the beneficial effect of S100B on injury-induced neurogenesis can be confirmed in mice when applied intraperitoneally (i.p.), and whether this effect is dose-dependent. METHODS: Male juvenile mice were subjected to a unilateral parietal cryolesion or sham injury, and treated with S100B at 20nM, 200nM or vehicle i.p. once daily. Hippocampal progenitor cell proliferation was quantified following labelling with bromo-deoxyuridine (BrdU, 50 mg/KG i.p.) in the germinative area of the dentate gyrus, the subgranular zone (SGZ), on day 4 as well as on cell survival and migration to the granular cell layer (GCL) on day 28. Progenitor cell differentiation was assessed following colabelling with the glial marker GFAP and the neuronal marker NeuN. RESULTS: S100B enhanced significantly the early progenitor cell proliferation in the SGZ as well as cell survival and migration to the GCL, and promoted neuronal differentiation. While these effects were predominately dose-dependent, 200nM S100B failed to enhance the proliferation in the SGZ on day 4 post-injury. CONCLUSION: We conclude that S100B participates in hippocampal neurogenesis after injury at lower nanomolar concentrations. Therefore S100B may serve as a potential adjunct treatment to promote neuroregeneration following brain damage.

Shunt-dependent hydrocephalus following subarachnoid hemorrhage correlates with increased S100B levels in cerebrospinal fluid and serum.

Posthemorrhagic hydrocephalus requiring permanent ventriculoperitoneal shunt placement is a major complication of aneurysmal subarachnoid hemorrhage (SAH). High S100B serum and cerebrospinal fluid (CSF) levels are considered to reflect the severity of brain injury. We prospectively assessed whether S100B levels in serum and CSF were predictive parameters for permanent shunt requirement following aneurysmal SAH. In patients suffering from aneurysmal SAH and treated with an external ventricular drain (EVD), S100B levels in serum and CSF were measured daily as long as the EVD was in place. S100B levels of patients who passed their EVD challenge were compared with those patients who required a permanent ventriculoperitoneal shunt placement. Out of 68 patients included in the study, 43 patients (63.2%) passed the EVD challenge and in 25 patients (36.8%) permanent ventriculoperitoneal shunting was performed. Group comparison revealed that in patients who required shunt placement, S100B was significantly higher in CSF (p < 0.05 at days 2, 4, 6, 10; p < 0.005 at days 1, 3, 5, 7, 8, 9) and serum (p < 0.05 at days 4-7) compared with patients who could be weaned from the EVD. Assessment of S100B levels in CSF and serum may be useful as a predictive parameter for shunt dependency in patients with posthemorrhagic hydrocephalus following aneurysmal SAH.

The atrial natriuretic peptide does not serve osmoregulation but predicts outcome following brain injury.

Atrial natriuretic peptide (ANP) plays an important role in body fluid homeostasis. ANP has been established as a marker of cardiac dysfunction and may play a role in brain edema development after traumatic brain injury (TBI). In order to identify its specific assignment following TBI, we related clinical data and treatment variables in 63 patients to longitudinal midregional (MR) proatrail natriuretic peptide (ANP) measurements. ANP correlated significantly to age (p < 0.0001) and vasopressin release (p < 0.001). Following TBI, ANP was increased initially and on day 3 (cut-off 100 pg/L) in 22% of the patients, in 31% on day 7, and was normalized at follow-up examination. The group comparison revealed that ANP levels did not significantly differ with regard to injury severity, but that high ANP levels predicted a worse Glasgow Outcome Score at 6 months (p < 0.05). While the initially intact osmoregulation - a correlation of urine volume and high serum sodium (r = 0.536, p = 0.003) or low urine osmolality (r = -0.556, p = 0.009) - got lost post-injury, the ANP release was triggered by volume load (p < 0.005). High ANP levels correlated with the neuroendocrine stress response, i.e., high cortisol (p = 0.05) and prolactin (p < 0.001) levels. We conclude that MR-proANP measurements reveal a significant predictive function for the prognosis of TBI.

The Passage of S100B from Brain to Blood Is Not Specifically Related to the Blood-Brain Barrier Integrity.

Following brain injury, S100B is released from damaged astrocytes but also yields repair mechanisms. We measured S100B in the cerebrospinal fluid (CSF) and serum (Cobas e411 electrochemiluminescence assay, Roche) longitudinally in a large cohort of patients treated with a ventricular drainage following traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH). Statistical analysis was performed with SPSS software applying the Mann-Whitney rank sum test or chi-test where appropriate. S100B in CSF and serum was significantly increased following TBI (n = 71) and SAH (n = 185) for at least one week following injury. High S100B levels in CSF and serum were inconsistent associated with outcome. The passage of S100B from CSF to blood (100( *)serum(S100B)/CSF(S100B)) was significantly decreased although the albumin quotient suggested an "open" blood-CSF barrier. Events possibly interfering with the BBB did not affect the S100B passage (P = .591). In conclusion, we could not confirm S100B measurements to reliably predict outcome, and a compromised blood-CSF barrier did not affect the passage of S100B from CSF to serum.