Interactions of histaminergic and serotonergic neurons in the hypothalamic regulation of prolactin and ACTH secretion

Serotonergic and histaminergic neuronal systems are both involved in mediation of the stress-induced release of the pituitary hormones prolactin (PRL) and ACTH. We investigated the possibility of an interaction between serotonin (5-HT) and histamine (HA) in regulation of PRL and ACTH secretion in conscious male rats. Animals were pretreated systemically with antagonists to 5-HT1, 5-HT2 or 5-HT3 receptors prior to intracerebroventricular (icv) administration of HA. The 5-HT1 + 2 receptor antagonist methysergide prevented and the 5-HT2 receptor antagonist LY 53857 attenuated the HA-induced PRL release while the 5-HT3 receptor antagonist ondansetron had no effect on this response. None of the three 5-HT receptor antagonists affected the ACTH response to HA. Specific blockade of HA synthesis by alpha-fluoromethylhistidine or blockade of postsynaptic HA receptors by icv infusion of the H1 receptor antagonist mepyramine or the H2 receptor antagonist cimetidine inhibited the PRL response to 5-HT or to the 5-HT precursor 5-hydroxytryptophan (5- HTP) given in combination with the 5-HT reuptake inhibitor fluoxetine (Flx). Blockade of the histaminergic system had no effect on the ACTH response to serotonergic stimulation. The H3 receptors are inhibitory HA receptors. Systemic pretreatment with the H3 receptor agonist R(alpha)methylhistamine, or the H3 receptor antagonist thioperamide had no effect on the hormone response to activation of the serotonergic system by 5-HTP plus Flx. We conclude that the serotonergic and histaminergic neuronal systems interact in their stimulation of PRL secretion, but not in their stimulation of ACTH secretion. This interaction involves serotonergic 5-HT1 and 5-HT2 receptors and histaminergic H1 and H2 receptors. Furthermore, the previously observed inhibitory effect of the H3 receptor agonist R(alpha)methylhistamine on stress-induced PRL and ACTH release seems not to be exerted by activation of presynaptic H3 receptors located on serotonergic neurons but rather on histaminergic neurons.     

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Holzeigenschaften von Buchen aus immissionsgeschädigten Beständen

In 48 trees from two immission-damaged beech stands in the Hils, Lower Saxonia, both over 100 years old, the anatomical wood properties at breast height (1,30 m) were investigated. From 24 trees out of each stand 12 trees belonged to damage class 0 and the others to damage class 2. On samples of the annual ring sequence 1975–85 and the undamaged annual ring sequence 1945–1955 fibre length, the water conducting tissue and the percentage of cell species were investigated. No abnormal variations of the anatomical wood properties due to immissions could be found.     

Harold L. Mitchell 65 Jahre

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Will the numbers add up for sub-7-nm magnetic spacings? Future metrology issues for disk drive lubricants, overcoats, and topographies

To achieve disk drive recording densities greater than one terabit per square inch, future head-media spacings (HMSs) will need to be less than 7 nm. This will place severe demands on the metrology tools used to measure the thickness and topographies of the contributors to the head-media spacing. Here, we first review some of the metrologies used for characterizing overcoats, lubricants, and topographies and discuss some of the limits that will make it difficult to achieve a sub-7-nm HMS. We next show new results for measuring lubricant redistribution on disk surfaces after contact with a small pad on the slider and present a new method for determining wear rates of these slider contact pads.     

Contact force measurement using acoustic emission analysis and system identification methods

Acoustic emission (AE) signals were used to investigate the contact force occurring at the head/disk interface of a computer hard drive. The AE sensor was calibrated directly using the “ball drop method” and indirectly using system identification. For the indirect calibration, a high bandwidth laser Doppler vibrometer (LDV) was used. The transfer function was established from the harmonic response derived at different vibration modes and frequencies. A finite element method based transient response simulation of impact was used to estimate the velocity and stress response of the slider. In our experiments, contact forces were found to be in the range of 5–25 mN for nano sliders and 2–10 mN for pico sliders.     

居德布兰河谷旅游项目—河边桑拿

河边桑拿位于一条美丽的河边,可以全景观赏远山的景色。它建在菲多斯景观酒店附近,供酒店的客人使用。桑拿房有一面玻璃墙,朝向景区。建筑物建在地形中,除玻璃墙外,四周用青草覆盖。     

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