[Effects of different training methods on cardiovascular autonomic regulation during bedrest].

Objective. To investigate the effects of different training methods on cardiovascular autonomic regulation under bedrest. Method. 15 healthy male volunteers aged 19-22 participated tests in head-down tilt (HDT) -6 degrees bedrest in order to observe the changes of cardiovascular system under simulated weightlessness. They were divided into control (5 men), hypoxia training (5 men) and Fangsong training (5 men) groups. 24 h dynamic ECG were recorded on the 2nd day of pre-bedrest, on the 3rd, 14th and 18th day of bedrest and on the 7th day of the post- bedrest. All spectra were estimated from entire 24 h HRV, before, during and after Fangsong and hypoxia training by autoregressive (AR) modeling method. Normalized low-frequency (LF%) was a quantitative marker of cardiac sympathetic activity, normalized high-frequency (HF%) reflected the changes in cardiac vagal activity, and LF/HF was considered to be related to sympathovagal balance or sympathetic activity. Result. In control group, LF% and HF% were all significantly reduced (P<0.05), LF/HL showed no significant changed during bedrest. In Fangsong group, HF% increased markedly (P< 0.05), while in hypoxia group, LF% increased markedly (P< 0.05). Conclusion. Fangsong training counteracted markedly the reduction in vagal activity, while hypoxia training counteracted markedly the decrease in sympathetic activity. It was possible that HRV indices could be used to evaluate the efficiency of countermeasures counteracting the adverse effects of weightlessness.

Effects of blocking GABA degradation on corticotropin-releasing hormone gene expression in selected brain regions.

PURPOSE: The gamma-aminobutyric acid (GABA) degradation blocker gamma-vinyl-GABA (VGB) is used clinically to treat seizures in both adult and immature individuals. The mechanism by which VGB controls developmental seizures is not fully understood. Specifically, whether the anticonvulsant properties of VGB arise only from its elevation of brain GABA levels and the resulting activation of GABA receptors, or also from associated mechanisms, remains unresolved. Corticotropin-releasing hormone (CRH), a neuropeptide present in many brain regions involved in developmental seizures, is a known convulsant in the immature brain and has been implicated in some developmental seizures. In certain brain regions, it has been suggested that CRH synthesis and release may be regulated by GABA. Therefore we tested the hypothesis that VGB decreases CRH gene expression in the immature rat brain, consistent with the notion that VGB may decrease seizures also by reducing the levels of the convulsant molecule, CRH. METHODS: VGB was administered to immature, 9-day-old rats in clinically relevant doses, whereas littermate controls received vehicle. RESULTS: In situ hybridization histochemistry demonstrated a downregulation of CRH mRNA levels in the hypothalamic paraventricular nucleus but not in other limbic regions of VGB-treated pups compared with controls. In addition, VGB-treated pups had increased CRH peptide levels in the anterior hypothalamus, as shown by radioimmunoassay. CONCLUSIONS: These findings are consistent with a reduction of both CRH gene expression and secretion in the hypothalamus, but do not support an indirect anticonvulsant mechanism of VGB via downregulation of CRH levels in limbic structures. However, the data support a region-specific regulation of CRH gene expression by GABA.

Complementary distributions of calbindin, parvalbumin and calretinin in the cerebellar vermis of the adult cat.

Immunocytochemistry was used to compare regional and cellular distribution of the calcium-binding proteins calbindin (CB), parvalbumin (PV) and calretinin (CR) in the cerebellar vermis of adult cats. CB and PV displayed similar patterns of distribution, mainly in Purkinje cells and their processes. Immunoreactive Purkinje cell axons were organised in bundles alternating with reaction-free strips, or raphes, of afferent fibres. In contrast, CR immunoreactivity was most apparent in unipolar brush neurons, and in mossy and climbing fibres. CR positive unipolar brush neurons were clustered and positive climbing fibres formed bands. Thus, CR was associated with afferent fibres and interneurons, and occurred in complementary structures to those demonstrated for CB and PV, mainly in efferent neurons and pathways.

Induction of NADPH-diaphorase activity in the forebrain in a model of intracerebral hemorrhage and its inhibition by the traditional Chinese medicine complex Nao Yi An.

Induction of NADPH-diaphorase (NDP) activity in the rat cerebral cortex was studied after autologous blood injection into the internal capsule as experimental model of intracerebral hemorrhage. The potential inhibitory effect on NDP induction by Nao Yi An (NYA), a complex derived from materials of animal and plant origin used in the treatment of intracerebral hemorrhage in traditional Chinese medicine, was also investigated. In animals without therapeutic treatment 2 and 4 days after injection of autologous blood, NDP activity was highly induced in pyramidal neurons in the neocortex, piriform, and entorhinal cortices, in astrocytes and in phagocytes in the hematoma and the area surrounding it, as well as in the subcortical white matter, and in endothelial cells in both the cortex and subcortical white matter bilaterally. Oral administration of NYA failed to inhibit NDP induction in endothelial cells but demonstrated a strong inhibitory effect on NDP activity induced in pyramidal neurons and astrocytes. NDP induction in phagocytes was also inhibited by the administration of NYA. Altogether the present results suggest that intracerebral hemorrhage in the internal capsule may induce nitric oxide synthase activity in different cell populations in the cortex and that administration of NYA can selectively inhibit such induction and, thus, potentially play a neuroprotective role.

Calcitonin gene-related peptide immunoreactivity selectively labels accessory optic nuclei and pathways of the rat visual system.

The present study shows the distribution of calcitonin gene-related peptide (CGRP)-immunolabeled neuronal somata and fibers in the accessory optic system of adult rats. CGRP-immunoreactive cell bodies were small to medium-sized and mostly fusiform or oval-shaped. Both immunolabeled somata and fibers were found in the dorsal and lateral terminal nuclei as well as in the interstitial nucleus of the superior fasciculus (posterior fibers); whereas only immunoreactive fibers were found in the ventral division of the medial terminal nucleus, particularly its rostral portion. These results indicate that CGRP-containing neurons are present in all nuclear components of the accessory optic system and suggest that this neuropeptide may play a neuromodulative role in eye movements.