Estimation of the time of death by measuring the variation of lateral cerebral ventricle volume and cerebrospinal fluid radiodensity using postmortem computed tomography.

Using postmortem CT (PMCT), changes in the volume of the lateral cerebral ventricles (LCVs) and modifications of the radiodensity of cerebrospinal fluid (CSF) have been examined to identify a possible relationship between these changes and the time of death. Subsequent periodical CT scans termed "sequential scans" for ten corpses at known time of death were obtained, and a 3D segmentation of the entire LCV was carried out to measure its volume and radiodensity over time from ~ 5.5- h up to 273-h postmortem. A linear decrease of the LCV volume for all the cases was observed in the investigated time range, together with an overall logarithmic increase of radiodensity. Although a larger sampling should be performed to improve the result reliability, our finding suggests that the postmortem variation of CSF radiodensity can be a potentially useful tool in determining postmortem interval, a finding that is worthy of further investigation.

Evaluation of post-mortem lateral cerebral ventricle changes using sequential scans during post-mortem computed tomography.

In the present study, we evaluated post-mortem lateral cerebral ventricle (LCV) changes using computed tomography (CT). Subsequent periodical CT scans termed "sequential scans" were obtained for three cadavers. The first scan was performed immediately after the body was transferred from the emergency room to the institute of legal medicine. Sequential scans were obtained and evaluated for 24 h at maximum. The time of death had been determined in the emergency room. The sequential scans enabled us to observe periodical post-mortem changes in CT images. The series of continuous LCV images obtained up to 24 h (two cases)/16 h (1 case) after death was evaluated. The average Hounsfield units (HU) within the LCVs progressively increased, and LCV volume progressively decreased over time. The HU in the cerebrospinal fluid (CSF) increased at an individual rate proportional to the post-mortem interval (PMI). Thus, an early longitudinal radiodensity change in the CSF could be potential indicator of post-mortem interval (PMI). Sequential imaging scans reveal post-mortem changes in the CSF space which may reflect post-mortem brain alterations. Further studies are needed to evaluate the proposed CSF change markers in correlation with other validated PMI indicators.

Acute stress-induced antinociception is cGMP-dependent but heme oxygenase-independent

Endogenous carbon monoxide (CO), which is produced by the enzyme heme oxygenase (HO), participates as a neuromodulator in physiological processes such as thermoregulation and nociception by stimulating the formation of 3′,5′-cyclic guanosine monophosphate (cGMP). In particular, the acute physical restraint-induced fever of rats can be blocked by inhibiting the enzyme HO. A previous study reported that the HO-CO-cGMP pathway plays a key phasic antinociceptive role in modulating noninflammatory acute pain. Thus, this study evaluated the involvement of the HO-CO-cGMP pathway in antinociception induced by acute stress in male Wistar rats (250-300 g; n=8/group) using the analgesia index (AI) in the tail flick test. The results showed that antinociception induced by acute stress was not dependent on the HO-CO-cGMP pathway, as neither treatment with the HO inhibitor ZnDBPG nor heme-lysinate altered the AI. However, antinociception was dependent on cGMP activity because pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) blocked the increase in the AI induced by acute stress.

Effect of Neuropeptide Y Injected into the Hypothalamic Suprachiasmatic Nucleus or the Lateral Cerebral Ventricle on Food Intake.

The effects of neuropeptide Y (NPY) injected into the hypothalamic suprachiasmatic nucleus (SCN) or the lateral cerebral ventricle (LCV) at four different time points of the day on the subsequent 2h food intake from three macronutrient rich diets were examined. Adult Wistar male rats on 12-12 h light-dark cycles received either saline or NPY (lOOpmol) through chronically implanted guide cannulas into the SCN or the LCV. The results show that NPY was effective at stimulating energy intake from the dextrin/sucrose diet when injected in the SCN after lights-on, and total energy intake when injected in the LCV before and after lights-on. This suggests that NPY is effective at altering nychthemeral variations in total energy and energy from dextrin/sucrose diets, but this modulation is specific to the site of administration.

INTRACEPHALIC DIFFUSION AND SELECTIVE LABELING OF PROPIDIUM IODIDE INJECTED INTO THE LATERAL CEREBRAL VENTRICLE / 解剖学报

Injections of propidium iedide (PI) into the lateral cerebral ventricle (LV) ofthe rat resulted in a prominent abnormality characterized by tremor,ataxia,andnystagmus.The intensity of PI fluorescence in the parenchyma of the brain fadedgradually away from the injection site and ventricles to the surfaces of the brain. In the forebrain it was seen that PI fluorescence reached the most lateral part ofthe ipsilateral caudate putamen nucleus.A constant neuronal labeling was observedin the septohippocampal nuclei,the A8-9-10 dopaminergic cell groups of themidbrain,the dorsal raphe nucleus,the median raphe nucleus,neurons within anddorsal to the medial lemniscus of the caudal midbrain,and Furkinje cells of thecerebellum.This neuronal labeling was bilateral.No distinct labeling was seen inother areas of the brain.Combined with Faglu histofluorescence,it was found thatalmost all of the dopaminergic neurons in the midbrain exhibited PI fluorescence.No labeled non-dopaminergic neuron was seen in A8-9-10.With a transection ofthe unilateral medial forebrain bundle,a prominent accumulation of PI fluorescencewas seen within the distal segments of catecholaminergic fibers near the transection,but no accumulation of PI was seen in the proximal segments.With LV injectionof Evans blue(EB)or DAPI or ethidium bromide,animals did not exhibit anyvisible abnormality.In animals with LV injection of EB or DAPI,although somelabeled cells were seen in the distant areas of the brain,their distribution wasdistinctly different from that of PI labeling.The above results indicate that besidesconfirming the LV injection of PI results in a prominent abnormality and PI isselectively uptaken by Purkinje cells,we have found that:a)PI is able to enter theparenchyma from the cerebrospinal fluid and diffuse widely in the brain;b)LVinjection of PI results in a selective labeling in certain specific areas of the brain,and those selectively labeled cells in A8-9-10 all are dopaminergic neurons;c)these dopaminergi(?) cells are labeled through axonal uptake and retrograde transportof PI.