Tomoyuki Matsuda

Functional morphology of the suprachiasmatic nucleus.

In mammals, the biological clock (circadian oscillator) is situated in the suprachiasmatic nucleus (SCN), a small bilaterally paired structure just above the optic chiasm. Circadian rhythms of sleep-wakefulness and hormone release disappear when the SCN is destroyed, and transplantation of fetal or neonatal SCN into an arrhythmic host restores rhythmicity. There are several kinds of peptide-synthesizing neurons in the SCN, with vasoactive intestinal peptide, arginine vasopressin, and somatostatine neurons being most prominent. Those peptides and their mRNA show diurnal rhythmicity and may or may not be affected by light stimuli. Major neuronal inputs from retinal ganglion cells as well as other inputs such as those from the lateral geniculate nucleus and raphe nucleus are very important for entrainment and shift of circadian rhythms. In this review, we describe morphological and functional interactions between neurons and glial elements and their development. We also consider the expression of immediate-early genes in the SCN after light stimulation during subjective night and their role in the mechanism of signal transduction. The reciprocal interaction between the SCN and melatonin, which is synthesized in the pineal body under the influence of polysynaptic inputs from the SCN, is also considered. Finally, morphological and functional characteristics of clock genes, particularly mPers, which are considered to promote circadian rhythm, are reviewed.

Cytochemical study of prolactin-releasing peptide (PrRP) in the rat brain.

Strong positive signals for PrRP mRNA and PrRP-like immunoreactivity (PrRP-LI) were detected in the nucleus of the solitary tract and ventral and lateral reticular formation of the caudal medulla oblongata. Weak mRNA signals and immunoreactivity were seen scattered from the hypothalamic dorsomedial nucleus (DMH) to ventromedial nucleus (VMH). Nerve processes and terminals with PrRP-LI were detected from the septal region to the diencephalon. These nerve processes were also clearly visible around capillary walls and in the vicinity of the ependymal cells of the third and lateral ventricles. These observations suggested that PrRP might be secreted into the systemic circulation and cerebrospinal fluid and may play functional roles other than in the release of prolactin from the anterior pituitary.

Peptide Expression in GABAergic Neurons in Rat Suprachiasmatic Nucleus in Comparison with Other Forebrain Structures: A Double Labeling In Situ Hybridization Study

We investigated the characteristics of GABAergic neurons in the rat suprachiasmatic nucleus (SCN) in normal untreated rats by examination of co-expressed peptides. We adopted double labeling in situ hybridization using a digoxigenin-labeled glutamic acid decarboxylase (GAD) riboprobe and 35S-labeled peptide riboprobes. GAD mRNA-positive neurons were distributed throughout the SCN from the rostral to the caudal pole. In the dorsomedial part of the SCN, most GAD mRNA-positive neurons co-expressed arginine vasopressin mRNA. In the ventrolateral part of the SCN, about two thirds of GAD mRNA-positive neurons co-expressed vasoactive intestinal peptide (VIP) mRNA. Co-expression of GAD and somatostatin mRNA was observed in virtually all neurons of the intermediate part of the SCN. In contrast, these peptidergic traits were poorly expressed in hypothalamic GABAergic neurons outside the SCN. Vasopressin mRNA-positive cells in the supraoptic nucleus did not express GAD mRNA, and co-expression of somatostatin mRNA and GAD mRNA was rare in the periventricular hypothalamic nucleus. Similarly, the VIP mRNA co-expression ratio of GABAergic neurons in the cerebral cortex was far lower than that in the SCN.

Vascular endothelial growth factor in epithelial lining fluid of patients with acute respiratory distress syndrome

Background and objective:  Vascular endothelial growth factor (VEGF) is known to contribute to the development of pulmonary oedema, and has been suggested to have a protective role against lung injury. To determine the role of VEGF in acute lung injury (ALI) and ARDS, VEGF levels were measured in lung epithelial lining fluid (ELF) collected from patients with ALI/ARDS.

Somatostatin neurons form a distinct peptidergic neuronal group in the rat suprachiasmatic nucleus: a double labeling in situ hybridization study☆

Accumulating evidence indicates that somatostatin (SS) is a key substance for the circadian rhythm of rodents. In the present study, we investigated whether SS mRNA coexists with arginine-vasopressin (AVP) mRNA, vasoactive intestinal peptide/peptide histidine isoleucine amide (VIP/PHI) mRNA and glutamate decarboxylase (GAD) mRNA in neurons of the rat suprachiasmatic nucleus (SCN) by double labeling in situ hybridization technique. SS mRNA-positive neurons were scattered in the whole region of rostral SCN, in the intermediate region between dorsomedial and ventrolateral region at the middle level, and in the mid to lateral region at the caudal level. These neurons were located in the close vicinities of the dorsomedial AVP and ventrolateral VIP/PHI mRNA-positive cell clusters. They rarely coexpressed AVP mRNA or VIP/PHI mRNA, but mostly coexpressed GAD mRNA. Thus, SS-synthesizing neurons are GABAergic and form a distinct cell group different from AVP or VIP/PHI cell groups.

Effects of hypothermia on c-fos and zif/268 gene expression following rat forebrain ischemia

AbstractPurpose. To determine the effects of prophylactic mild hypothermia against transient forebrain ischemia, we examined the levels and localization of c-fos and zif/268 gene expression in the rat hippocampal formation at an early period during reperfusion. Methods. For the histochemical evaluation, Wistar rats were divided into three groups: normothermia (37°C) during ischemia (n = 5), hypothermia (34°C) during ischemia (n = 5), and sham-operated controls (n = 5). The former two groups were subjected to 10-min forebrain ischemia using the bilateral carotid artery occlusion with arterial hypotension (35 mmHg) technique. After 60 min of reperfusion, the brains were removed and the in situ hybridization technique was used to detect c-fos and zif/268 mRNA expression. Additionally, to determine the histopathological changes of neuronal degeneration, animals were treated with hypothermia during ischemia (n = 4) and normothermia during ischemia (n = 4). They were allowed to survive for 7 days, and then the sections of hippocampal formation were examined by light microscopy. Results. Transient ischemia increased c-fos and zif/268 mRNA signal densities from 1.8- to 6.1-fold compared with that in controls in the hippocampus. Mild hypothermia significantly inhibited the induction of c-fos and zif/268 (P < 0.01). In the CA1 subfield, hypothermia protected against delayed neuronal degeneration (P < 0.05), which was observed after normothermic ischemia. Conclusion. The induction of transcription factor-related immediate early genes (IEGs) was a sensitive marker of the cellular response to ischemia. Mild hypothermia uniformly inhibited the induction of IEGs in the hippocampus, but the mechanisms underlying the protective effect of hypothermia against neuronal degeneration cannot be explained only by the IEGs.

Effect of postischemic hypothermia on neuronal apoptosis and bax expression after forebrain ischemia in gerbils

We investigated the tempoml and spatial expression of c-fos. HSWO. (‘OS-,. 7 and ncurotrophins (NM’. BDNl.. N’l’-3) mRNA in the ischemic core and the peripheral cortex of 2h r\lC.\ occlusion rats b!, in situ hybridization histochemistt-) \Ve found no signals of each mRN.4 in the ischemic core. ( 111 th other hand. in the surroundin, 0 of ischemic territory. expression of c-fos. COaX-2. HSWO and BDNF mRU.4 were demonstrated. NGF and _\l‘-3 signals were absent in the ischenuc cortex. Expression of HSP70 mRN.4 was restricted to narrow rim in the periphel?: of the ischemic tenitoc. but c-fos and l3tP.T expression were propagated to more large peripheral cortex. Durin, 0 2 hours 11(‘.\ occlusion. xlgS( 14 in the amount of O.lmM/Kg were infused intravenously,. Volumetric measurements demonstrated a statistically significant decrease in infarct size for MgSO4 treatment groups, We also found that the up-regulation of c-fos and BDNF mR\.-\ levels in the surrounding ischemic cortex were attenuated in hlgSO4 treatment groups. In conclusion, we ma! say that the intravenous hIgS( )_I can attenuate the excessive response of c-fos and BDhF mRN.1 from ischemic neuron.

1237 Effect of postischemic hypothermia on neuronal apoptosis after forebrain ischemia in gerbils

Keiji Igase’ , Seiji Matsuda’ , Jyunya Tanaka2, Masahiro Sakanaka’ Prosaposin as the precursor of saposins A, B, C, and D has been shown to possess neurotrophic activity which is ascribed to an 18-mer peptide comprising the hydrophilic sequence of saposin C. In this study, we examined the effects of the l&mer peptide in stroke-prone spontaneous hypertensive rats with permanent occlusion of the middle cerebral artery (MCA). After MCA occlusion, intracerebroventricular infusion of the 18-mer pep tide at a dose of 4, 20, and 60ng/day or vehicle was started and lasted 4 weeks. In the Morris water-maze tests performed at 2 and 4 weeks after MCA occlusion, the escape latency of rats infused with the l&mer peptide at doses of 20 and 60ngjday was significantly shorter than that of vehicle-infused rats. Subsequent histological analysis showed that cortical infarction was attenuated by treatment with the high dose of the peptide. Moreover, treatment with the peptide significantly prevented the secondary thalamic degeneration in a dose-dependent manner.

Persistent upper airway obstruction after aneurysmectomy of brachiocephalic trunk.

Tracheal compression is a well-recognized complication of aneurysm of the aortic arch and its main branches. In many cases, surgical resection of the aneurysm relieves the respiratory insufficiency and residual tracheomalacia in adults is rare. We present a case in which progressive tracheal compression caused by an aneurysm resulted in tracheomalacia and residual severe airway obstruction even after surgical repair of the aneurysm. The patient was subsequently treated with plastic repair of the trachea with a favorable result.