Comments on Hausmann et al.: Neuronal apoptosis following human brain injury

Neuronal and glial apoptosis in human traumatic brain injury

To establish reliable methods to aid the timing of brain damage after traumatic brain injury (TBI), brain tissue from 56 autopsy cases with TBI and known survival times, ranging from a few minutes to 126 days, were tested for apoptotic changes to the neuronal and glial cells. Apoptosis was established using the TdT-mediated dUTP nick end labelling (TUNEL) method of in-situ labelling and immunohistochemical reaction of caspase 3. In addition, cellular reaction and astroglial cell differentiation were investigated using histological and immunohistochemical markers. From a survival time of 120 min up to 12 days, TUNEL-positive apoptotic neuronal cells were frequently detected in the contusion zone. The earliest positive caspase 3 reaction in cortical neurons was evident after a posttraumatic interval of 80 min. Detection of apoptotic glial cells using the TUNEL technique showed that as in the case of neuronal cells, the earliest positive TUNEL reaction was obtained after 110 min. In cases of survival times of 120 min up to 4 days, apoptotic glial cells could frequently be detected. However, the first caspase 3-positive glial cells appeared 5 h after injury. Cerebral apoptosis was significantly associated with TBI cases as compared to control cases (P<0.001). The reference histological findings of neutrophilic granulocytes, CD3-positive T-lymphocytes, CD68-positive activated microglial cells/macrophages and TUNEL-positive neuronal cells increases the degree of certainty in determining the probable age of traumatic brain injury to 87.5%.

Immunohistochemical investigation of dopaminergic terminal markers and caspase-3 activation in the striatum of human methamphetamine users

Methamphetamine (METH) has been shown to induce neurotoxicity. In a previous human study using quantitative Western blotting and radioligand binding assay, dopaminergic terminal marker deficits were induced in chronic METH users. In this study, we examined the suitability of the immunohistochemical detection of tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicular monoamine transporter-2 (VMAT2) levels, and caspase-3 activation in the striatum to diagnose METH abuse. Decreases in TH immunoreactivity in the nucleus accumbens and DAT in the nucleus accumbens and putamen were induced in METH users, whereas a significant difference of VMAT2 was not evident between METH and control groups. However, in the nucleus accumbens of two METH users, levels of VMAT2, a stable marker of striatal dopaminergic terminal integrity, were reduced remarkably. These findings might indicate that dopaminergic terminal degeneration is induced in the striatum of some METH abusers. On the other hand, we observed little caspase-3 activation, indicative of apoptosis, in the striatal neurons of chronic METH users. Overall, the findings of dopaminergic terminal markers were similar to those in the previous human study. Therefore, it is suggested that immunohistochemical techniques could be used to examine dopaminergic terminal marker levels and could also give useful information on chronic and/or lethal METH use in cases of METH-related death, where METH intoxication may not be toxicologically demonstrated.