Direct effects of serotonin and ketanserin on the functional morphology of embryonic chick skin in vitro

Summary Different organotypical culture methods are used to test the direct effects of serotonin and ketanserin, a S₂, α₁, and H₁ receptor antagonist in vascular tissue, on fibroblasts and epidermal cells of embryonic chick skin in vitro. From light microscopic and electron microscopic analyses, we learn that serotonin enhances keratinization and differentiation, whereas ketanserin reduces differentiation in comparison to the control cultures. Incorporation data of fragments cultured with [³H]thymidine show that ketanserin, within a dose range from 0.05 to 5 μg/ml, stimulates proliferation. Serotonin at a concentration of 10 μg/ml slightly slows down proliferation, whereas lower doses of 0.1 and 1 μg/ml result in tritium activities that do not differ from control cultures. This investigation was financially supported by the National Fund of Scientific Research, Belgium, 3.0022.87.     

How chicken embryo survives after half of shell is sealed?

The goal of this study was to explore the development of the gas transport systems in chick embryos after half of the shell surface is closed on incubation day 11. By the end of day 3 of the experiment (incubation day 14), the vascular reduction in the chorioallantois under the covered zone is fully compensated by the vessel dilatation and growth in the intact half. In parallel, the oxygen capacity of blood elevates and hematopoiesis increases: the indices of hematocrit, hemoglobin, and erythrocyte count increase by half. The development of the left ventricular myocardium accelerates through the myocyte hyperplasia and their more mature ultrastructure. The obtained data indicate that hypoxia accelerates the embryonic development and leads to earlier and faster differentiation of the gas transport systems. However, the efficiency of antihypoxic responses is limited by the upper bound of capillary density in the chorionic respiratory network. After 1 week of the experiment (incubation day 18), the total vascular volume in the chorioallantois is halved relative to control, while the arterial walls substantially thicken in the open part, which increases the peripheral resistance. Coronary sclerosis and dystrophy of cardiomyocytes developed in the left ventricle. These general hemodynamic abnormalities are accompanied by a notable embryonic growth inhibition. Thus, the structural compensation of the gas transport systems in the experiment becomes exhausted and cannot provide for increasing metabolic demands of the growing embryo.     

Differences in serotonergic neurotransmission between rats displaying high or low anxiety/depression-like behaviour: effects of chronic paroxetine treatment

Disturbances in serotonergic neurotransmission have been suggested to be closely interlinked with hyperactivity of the hypothalamic-pituitary-adrenocortical (HPA) system, and are likely to be involved in the pathophysiology of anxiety disorders and major depression. We therefore investigated markers of serotonergic transmission and their modulation by chronic paroxetine in rats selectively bred for high (HAB) or low (LAB) anxiety-related behaviour, both under basal conditions and in response to emotional stress. Hippocampal serotonin 1 A (5-HT1A) receptor mRNA expression was reduced in HAB rats, whereas 5-HT concentrations in hippocampal microdialysates did not differ between HAB and LAB rats under basal conditions. In the hippocampus, overall expression of serotonin transporter binding sites was increased in HAB compared with LAB rats. Exposure to emotional stress failed to increase intrahippocampal 5-HT release in HAB rats whereas LAB rats displayed a physiological, albeit small rise. Chronic paroxetine treatment markedly increased the stress-induced rise in hippocampal 5-HT in HAB, but not LAB rats. This effect may be (at least in part) related to a greater down-regulation of hippocampal serotonin transporter binding sites by paroxetine in HABs compared with LABs, while 5-HT1A receptor expression remained unaffected in this brain area. The findings indicate reduced hippocampal serotonergic transmission in HAB rats as compared with LAB rats, which is evident both at the presynaptic (5-HT release) and the postsynaptic (5-HT1A receptor) level. Chronic paroxetine enhanced the presynaptic responsivity in HAB rats, but not LAB rats, pointing to a preferential efficacy of paroxetine in rats with enhanced anxiety/depression-related behaviour.     

鸡胚发育后期心电图的无损测定及心率变化

目的：测量鸣胚发育后期心电图,测定鸡胚发育后期心率及其变化.方法：利用壳膜外电极测量鸡胚心电图,根据RR间期计算鸡胚心率。结果：引出了具有较为清晰Q波、R波（振幅在8—20μV波动）、S波的鸡胚心电图。鸡胚的QRs间期在发育后期无明显变化,心率在D14～D20早期的心率变化较小,在D20后期和D21显著增加（P〈0．01）。结论：建立了壳膜外记录鸡胚心电图的方法,鸡胚在啄壳期心率显著增加.     

Microwave effects on isolated chick embryo hearts

This study was designed to examine the effects of microwaves on the electric activity of hearts as a means of elucidating interactive mechanisms of nonionizing radiation with cardiac tissue. Experiments were performed on isolated hearts of 9-12-day-old chick embryos placed in small petri dishes. Oxygenated isotonic Ringer's solution at 37 degrees C permitted heart survival. Samples were irradiated at 2.45 GHz with a power density of 3 mW/cm2. The heart signal was detected with a glass micropipet inserted into the sinoatrial node and examined by means of a Berg-Fourier analyzer. Pulsed microwaves caused the locking of the heartbeat to the modulation frequency, whereas continuous wave irradiation might have induced slight bradycardia. Pulsed fields induced stimulation or regularization of the heartbeat in arrhythmia, fibrillation, or arrest of the heart.     

鸡胚模型在生物研究中的应用进展

实验动物模型在预防、诊断、治疗疾病和探讨疾病的发生机制等方面起到了至关重要的作用。鸡胚发育过程清楚,利用鸡胚本身的结构特点,可作为研究与胚胎发育相关的生物学实验模型。另外,鸡胚绒毛尿囊膜（CAM）血管丰富,是天然免疫缺陷宿主,可作为血管药理学、肿瘤学等方面研究的一个较为理想的实验模型。本文综述了鸡胚模型在生物实验研究中的应用进展。     

Enantiomers of 11-hydroxy-10-methylaporphine having opposing pharmacological effects at 5-HT1A receptors

The two enantiomers of the title compound have been prepared by different synthetic routes. Both bind strongly to 5-HT1A receptors from rat forebrain membrane tissue. However, in a guinea pig ileum preparation, the (R)-enantiomer exhibits properties consistent with its being an agonist, whereas the (S)-enantiomer shows no agonist effect, but it blocks the actions of the (R)-enantiomer and of 8-hydroxy-2-di-n-propylaminotetralin (8-OH-DPAT), a 5-HT1A agonist. These data are presented as a rare example of enantiomers which demonstrate opposite pharmacological effects at the same receptor.     

Segmental independence and age dependence of neurite outgrowth from embryonic chick sensory neurons

Targets in limb regions of the chick embryo are further removed from the dorsal root ganglia that innervate them compared with thoracic ganglion-to-target distances. It has been inferred that axons grow into the limb regions two to three times faster than into nonlimb regions. We tested whether the differences were due to intrinsic properties of the neurons located at different segmental levels. Dorsal root ganglia (DRG) were isolated from the forelimb, trunk, and hind limb regions of stage 25–30 embryos. Neurite outgrowth was measured in dissociated cell culture and in cultures of DRG explants. Although there was considerable variability in the amount of neurite outgrowth, there were no substantive differences in the amount or the rate of outgrowth comparing brachial, thoracic, or lumbosacral neurons. The amount of neurite outgrowth in dissociated cell cultures increased with the stage of development. Overall, our data suggest that DRG neurons express a basal amount of outgrowth, which is initially independent of target-derived neurotrophic influences; the magnitude of this intrinsic growth potential increases with stage of development; and the neurons of the DRG are not intrinsically specified to grow neurites at rates that are matched to the distance they are required to grow to make contact with their peripheral targets in vivo. We present a speculative model based on Poisson statistics, which attempts to account for the variability in the amount of neurite outgrowth from dissociated neurons. © 1995 John Wiley & Sons, Inc.     

Perfluorocarbon-based medium for culture of the early chick embryo heart

Summary In an attempt to prolong the survival of the explanted early chick embryo heart, hearts at stages 10 to 28 were cultured in supplemented Dulbecco's modified Eagle's medium with or without the perfluorocarbon, perfluorotributylamine. The perfluorocarbon was added to the standard culture medium in a 50∶50 (vol/vol) mixture. Explants were evaluated daily and were harvested for light microscopy after 2 to 10 d in culture. The tubular shape of the explants was generally maintained for 2 d in culture, after which the hearts became dilated or spherical. Beating was noted in some of the explants on Day 2 in culture but not thereafter. Microscopic evaluation showed patchy areas of necrosis in all explants by Day 3, although large areas of viable epithelioid cells were documented as long as 7 d after explantation. State 16 to 18 hearts cultured in the presence of perfluorocarbon were more likely to maintain tubular architecture on microscopy than hearts cultured in standard medium. Hearts cultured from later stages showed no improvement in appearance with the presence of perfluorocarbon and there was a suggestion of increased necrosis in later-stage explants cultured with pefluorocarbon for 4 d. Further modification of the culture system will be required to prolong explant survival and development beyond 2 d.