Ecological conditions, flora and vegetation of a large doline in the Mecsek Mountains (South Hungary)

Vegetation-environment relationships were investigated in a large doline of the Mecsek Mts (South Hungary). To reveal the vegetation pattern, we collected vegetation data and environmental variables along a 243 m long transect. Atotal of 144 vascular plant species and 4 vegetation types were identified in the doline.We found that both the species composition and the vegetation pattern are significantly influenced by air temperature, air humidity, soil moisture and altitude. Our results confirm the putative temperature and vegetation inversion in the doline

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Dehydroepiandrosterone regulates astroglia reaction to denervation of olfactory glomeruli

Effects of dehydroepiandrosterone (DHEA) on glial reactions of the peripherally denervated olfactory bulb were studied in adult male rats. Denervation was achieved by destroying the olfactory mucosa with ZnSO 4 (0.17 M) irrigation of the nasal cavities. In one series of experiments, chronic DHEA treatment was applied (daily injections for 7 days, i.p., 10 mg/kg b.w. and 25 mg/kg b.w.); in the other series of experiments, animals received a single injection of DHEA (i.p., 10 mg/kg b.w., 25 mg/kg b.w. and 50 mg/kg b.w.) 2 h following ZnSO4 treatment. To determine whether DHEA conversion to estradiol was involved in the mechanism of DHEA action on glia, a third series of experiments was carried out in which the aromatase inhibitor fadrozole (4.16 mg/ml) was administered using subcutaneously implanted osmotic minipumps. Rats were killed on day 7 after chemical denervation, and the reaction of glial cells was monitored within the olfactory bulb, using GFAP and vimentin immunohistochemistry. Qualitative changes in GFAP expression were analyzed by Western blot. Chronic DHEA treatment with both doses (10 mg/kg b.w. and 25 mg/kg b.w.) and acute DHEA treatment with the highest dose applied (50 mg/kg b.w.), inhibited the increase in GFAP expression induced by the denervation of the olfactory bulb. Furthermore, GFAP and vimentin immunostaining in the glomerular layer of the olfactory bulb were diminished in the denervated and DHEA treated groups. However, when DHEA treatment was combined with fadrozole administration, such a decrease in GFAP expression could not be detected in the chemically denervated olfactory bulb. These findings indicate that DHEA, depending on the dose applied and the mode of administration, attenuates glial reaction to denervation and may regulate glial plasticity in the olfactory glomeruli. These effects are likely to be mediated at least in part by the conversion of DHEA to estradiol. © 2004 Wiley-Liss, Inc.Peer Reviewe

Oestrogen-modulated increase of calmodulin-dependent protein kinase II (CamKII) in rat spinal trigeminal nucleus after systemic nitroglycerin

peer reviewedMigraine can be triggered by systemic administration of the nitric oxide (NO) donor nitroglycerin (NTG) and by abrupt falls in plasma oestradiol. Calmodulin-dependent protein kinase II (CamKII) present in superficial dorsal horns is thought to play a role in sensitization of central nociceptors, a phenomen present in migraineurs. We therefore examined in rats the expression of CamKII in the caudal trigeminal nucleus (TNC) after subcutaneous NTG (10 mg/kg) and its modulation by oestrogen. In male rats and in ovariectomized females, after 4 h NTG increased significantly CamKII expression in the superficial layers of TNC, but not in the upper thoracic spinal cord. NTG had no effect on CamKII expression in oestradiol-treated ovariectomized animals. Thus NTG, i.e. NO, selectively enhances CamKII in the rat TNC and oestradiol blocks this effect. These data may help to understand the mechanisms by which NO triggers migraine attacks and oestrogens influence migraine severity

Fluctuation of synapse density in the arcuate nucleus during the estrous cycle

The hypothalamic arcuate nucleus integrates different hormonal and neural signals to control neuroendocrine events, feeding, energy balance and reproduction. Previous studies have shown that in adult female rats the arcuate nucleus undergoes a cyclic fluctuation in the number of axo-somatic synapses during the estrous cycle, in parallel to the variation of ovarian hormone levels in plasma. In the present study we have used an unbiased stereological analysis in conjunction with postembedding immunocytochemistry to assess whether the synaptic remodeling during the estrous cycle in rats is specific for certain types of synapses. Our findings indicate that there is a significant decrease in the number of GABAergic axo-somatic synapses on proestrus afternoon and estrus day compared with other days of the estrous cycle. This decrease in GABAergic synapses is accompanied by an increase in the number of dendritic spine synapses. The synaptic density appears to cycle back to proestrus morning values on metestrus day. In contrast, the number of synapses on dendritic shafts does not change during the cycle. These results indicate that a rapid and selective synaptic turnover of arcuate synapses occurs in physiological circumstances. © 2006 IBRO.Peer Reviewe

Effect of axotomy and 17beta-estradiol on P2X7 receptor expression pattern in the hypoglossal nucleus of ovariectomized mice

The objective of the study was to examine whether axotomy and 17beta-estradiol affects P2X7 receptor expression and distribution in the hypoglossal nucleus. The left hypoglossal nerve of ovariectomized mice was cut and animals received a single injection of 17beta-estradiol (25mug/100 g b. w. in 20% (2- hydroxypropyl) - beta- cyclodextrin) or vehicle one hour after axotomy. Mice were sacrificed on day 4 following surgery. The area fraction of P2X7 receptor immunoreactive structures and of CD11b immunolabeled microglia, P2X7 protein concentration, and the immunoreactivity pattern of estrogen receptor alpha / beta were analyzed on both sides of the hypoglossal nucleus. Following axotomy the area fraction of P2X7 immunoreactive neurons showed a decreasing tendency, while the area fraction of P2X7 immunolabeled microglia increased significantly on the axotomized side compared with the control side in mice injected with vehicle. In animals treated with 17beta-estradiol the decrease in area fraction of neural and the increase in area fraction of microglial P2X7 immunostaining on the axotomized side were significantly enhanced compared with animals injected with vehicle. The P2X7 immunoreactivity pattern on the control side of the nucleus remained unchanged after 17beta-estradiol injection. Semi-quantitative Western blots revealed no significant difference in P2X7 protein concentration comparing the axotomized side with the control side in either experimental group. The CD11b immunoreactive microglia area fraction increased significantly following axotomy, but was not affected by 17beta-estradiol. Neither estrogen receptor alpha, nor beta colocalized with CD11b. Our results suggest that axotomy induces cell-type specific changes in P2X7 receptor expression, which may be directly regulated by 17beta-estradiol through estrogen receptor alpha or beta in neurons, but not in activated microglia

Hormonal enhancement of neuronal firing is linked to structural remodelling of excitatory and inhibitory synapses

The ovarian hormone estradiol induces morphological changes in the number of synaptic inputs in specific neuronal populations. However, the functional significance of these changes is still unclear. In this study, the effect of estradiol on the number of anatomically identified synaptic inputs has been assessed in the hypothalamic arcuate nucleus. The number of axo-somatic, axodendritic and spine synapses was evaluted using unbiased stereological methods and a parallel electrophysiological study was performed to assess whether synaptic anatomical remodelling has a functional consequence on the activity of the affected neurons. Estradiol administration to ovariectomized rats induced a decrease in the number of inhibitory synaptic inputs, an increase in the number of excitatory synapses and an enhancement of the frequency of neuronal firing. These results indicate that oestrogen modifications in firing frequency in arcuate neurons are temporally linked to anatomical modifications in the numerical balance of inhibitory and excitatory synaptic inputs