Stimulation of ribonuclease activity and its isoenzymes in germinating seeds of cowpea (Vigna sinensis) by gibberellic acid and adenosine-3′,5′-cyclic monophosphate

Summary Application of GA₃ and cyclic AMP to cowpea seedlings caused a 2–3 fold stimulation of RNAase activity, together with the augmentation of RNAase isoenzymes. Inhibitor studies indicated the requirement of fresh RNA and protein synthesis for enzyme stimulation.     

Inhibition of TSH-stimulated thyroid hormone release and potentiation of TRH-stimulated TSH release by indomethacin in perifusion systems of rat thyroids and pituitaries

Using indomethacin (Ind), a prostaglandin synthesis inhibitor, in vivo experiments in rats and in vitro experiments with perifusion systems of rat thyroids and pituitaries were conducted. After 35 days of intragastric infusion of Ind, serum TSH levels were markedly increased, the thyroid was swollen and, as a consequence, T3 and T4 levels were normal. The T3 release from perifused rat thyroids under continuous stimulation with 10 mU/ml TSH was inhibited significantly (p less than 0.01) by 1.0 X 10(-6) M Ind. On the other hand, the TSH release from perifused rat pituitaries under TRH stimulation was enhanced conspicuously by Ind. It was concluded that Ind decelerated thyroid hormone release from the thyroid and accelerated TSH release from the pituitary in perifusion systems.     

Inhibition of TSH-stimulated thyroid hormone release and potentiation of TRH-stimulated TSH release by indomethacin in perifusion systems of rat thyroids and pituitaries

Summary Using indomethacin (Ind), a prostaglandin, synthesis inhibitor, in vivo experiments in rats and in vitro experiments with perifusion systems of rat thyroids and pituitaries were conducted. After 35 days of intragastric infusion of Ind, serum TSH levels were markedly increased, the thyroid was swollen and, as a consequence, T₃ and T₄ levels were normal. The T₃ release from perifused rat thyroids under continuous stimulation with 10 mU/ml TSH was inhibited significantly (p<0.01) by 1.0×10^–6 M Ind. On the other hand, the TSH release from perifused rat pituitaries under TRH stimulation was enhanced conspicuously by Ind. It was concluded that Ind decelerated thyroid hormone release from the thyroid and accelerated TSH release from the pituitary in perifusion systems.     

Serum-induced stimulation of snRNA synthesis in mouse 3T3 fibroblasts

Small nuclear RNAs (snRNAs) from quiescent and serum-stimulated 3T3 cultures, labeled with [3H]uridine [( 3H]U), were electrophoresed in polyacrylamide-urea slab gels and revealed by staining with ethidium bromide and by fluorography. Judged by labeling with [3H]U, synthesis of 7S and U1-U6 RNAs was very low or absent in quiescent cultures. The serum-induced transition of 3T3 cells from a resting to a growing state was accompanied by an early, apparently sequential stimulation of snRNA synthesis; stimulated synthesis of 7S, U1, U2, U3, U4 and U6 RNAs coincided in time with serum-induced stimulation of 45S pre-ribosomal RNA (pre-rRNA) and heterogeneous nuclear RNA (hnRNA) synthesis.     

Moderate cooling depresses the accumulation and the release of newly synthesized catecholamines in isolated canine saphenous veins

Moderate cooling (from 37 degrees to 24 degrees C) depressed the formation of 3H-dopamine and 3H-norepinephrine from 3H-tyrosine by isolated canine saphenous veins. Cooling reduced the evoked release of newly synthesized catecholamine to the same extent as that of stored norepinephrine. Hence the augmentation by cold of the contractile response to sympathetic nerve stimulation observed in earlier work is not accompanied by an augmented release of newly synthesized norepinephrine.     

Serum-induced stimulation of snRNA synthesis in mouse 3T3 fibroblasts

Summary Small nuclear RNAs (snRNAs) from quiescent and serum-stimulated 3T3 cultures, labeled with [³H]uridine ([³H]U), were electrophoresed in polyacrylamide-urea slab gels and revealed by staining with ethidium bromide and by fluorography, Judged by labeling with [³H]U, synthesis of 7S and U1-U6 RNAs was very low or absent in quiescent cultures. The serum-induced transition of 3T3 cells from a resting to a growing state was accompanied by an early, apparently sequential stimulation of snRNA synthesis; stimulated synthesis of 7S, U1, U2, U3, U4 and U6 RNAs coincided in time with serum-induced stimulation of 45S pre-ribosomal RNA (pre-rRNA) and heterogeneous nuclear RNA (hnRNA) synthesis.     

氧化型低密度脂蛋白诱导3T3-L1脂肪细胞内质网应激相关标志物p-eIF2a、CHOP表达

目的 观察氧化型低密度脂蛋白(oxidized low density lipoprotein,ox-LDL)诱导3T3-L1脂肪细胞内质网应激相关标志物p-eIF2a、CHOP的表达,探讨ox-LDL对3T3-L1脂肪细胞内质网应激的诱导作用.方法 体外培养3T3-L1脂肪细胞,用ox-LDL分别干预脂肪细胞6小时、12小时、24小时,用RT-PCR检测CHOP mRNA表达,用Western blot检测p-eIF2a、CHOP蛋白表达.结果 ox-LDL可诱导脂肪细胞p-eIF2a、CHOP表达,p-eIF2a表达发生在ox-LDL作用早期(6小时,12小时),24小时表达有所下降,而CHOP的表达强度随时间增加,24小时表达达到高峰.结论 ox-LDL可诱导3T3-L1脂肪细胞发生内质网应激,激活未折叠蛋白反应信号通路.p-eIF2a表达发生在ox-LDL作用早期,而CHOP的表达强度呈时间依赖性.     

Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate as an antagonist of the stimulatory action of cyclic AMP on the ouabain-insensitive Na efflux in single barnacle muscle fibers

Single muscle fibers of the barnacle Balanus nubilus have been used as a preparation to test the possibility that the Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate, which is the first available analog of cAMP that acts as an antagonist of cAMP, may reduce the magnitude of cAMP-mediated stimulation of the resting ouabain-insensitive Na efflux. The results obtained show that this antagonist is, in fact, able to reduce stimulation of the Na efflux by injected cAMP in a dose-dependent manner.     

Opiate receptor sites in neuronal and glial cell lines in culture]

A stereospecific saturable high affinity binding of 3H-naloxone has been found in 3 glial and 2 neuronal cell lines. Kinetic study of binding seems to indicate only one class of receptor sites in the 5 cell lines. Acute exposure to morphine (1 X 10(-5)M) concurrent with PGE1-induced stimulation of adenylate cyclase did not result in a decrease of the cAMP level in any cell line tested.     

Platelet heterogeneity and dense tubular system changes on activation

Platelets impregnated with heavy metals appeared as 3 distinct morphological types: 'reticular' cells with a polygonal dense tubular network and stained granules, dark metallophilic cells, and pale metallophobic cells with microvesicles and non-staining granules. On stimulation, type 1 cells decreased while type 3 cells increased, suggesting that with activation dense tubules break up into microvesicles and granules become metallophobic. In the type 2 cells a different functional mechanism may exist.     

Sympathetic,muscarinic vasodilation in cranial vessels of the cat

Summary Pressor responses evoked by stimulation of the preganglionic sympathetic trunk of the feline superior cervical ganglion have been recorded in vivo from the vascular bed perfused by one external carotid and the vertebral artery. When vasoconstrictor activity is blocked and potential vasodilator activity enhanced by close, intracarotid injection of guanethidine and prostaglandin F₂ respectively, stimulation evokes a weak pressor response followed, on cessation of stimulation, by a prolonged vasodilation lasting for 6–8 min. The magnitude and duration of the poststimulation vasodilation was reduced significantly by atropine. Due to the prolonged nature of the vasodilation, it is unlikely that a sympathetic cholinergic vasodilation in the classical sense is involved.     

Recurrent inhibition of the monosynaptic reflex in the upper caudal cord of the cat

Summary In spinal cats both ipsi- and contralateral antidromic volleys in the 3rd sacral ventral roots produce recurrent inhibition of the monosynaptic reflex evoked by stimulation of the 1st caudal dorsal root and recorded from the corresponding ventral root.     

Recurrent inhibition of the monosynaptic reflex in the upper caudal cord of the cat.

In spinal cats both ipsi- and contralateral antidromic volleys in the 3rd sacral ventral roots produce recurrent inhibition of the monosynaptic reflex evoked by stimulation of the 1st caudal dorsal root and recorded from the corresponding ventral root.     

A negative inotropic effect of acetylcholine in the presence of several phosphodiesterase inhibitors

The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine (IBMX) reveal a negative inotropic effect of acetylcholine in cat ventricular heart muscle. This effect in unrelated to beta-adrenoceptor stimulation and possibly mediated by the accumulation of cyclic GMP.     

Perception of olfactory and intranasal trigeminal stimuli following cutaneous electrical stimulation

Based on previous research it may be hypothesized that the perception of odorants is modified by an axon reflex emanating from trigeminal afferents activated via the skin and/or the intranasal respiratory epithelium. The present experiment investigated the effects of trigeminal cutaneous stimulation on intensity estimates of intranasal chemical stimuli. While the left nostril was stimulated chemically with olfactory and trigeminal stimulants, four regions of the face were stimulated electrically. Intensity estimates of the chemical stimuli tended to increase after cutaneous electrical stimulation which may be interpreted in terms of response priming. The effect of electrical stimulation did not differ at the 4 stimulation sites. The results argue against the hypothesis that the processing of intranasal chemical stimuli is modified peripherally by cutaneous trigeminal excitation.     

External factors and ecdysone release inCalliphora erythrocephala

Summary Ecdysone level is measured in the haemolymph of normal larvae and of larvae submitted to external stimulation. External stimulation delays the release of ecdysone and the formation of puparium. The adaptative value of the mechanism which connects the ecdysone titre to external stimulation is discussed.     

Early effect of estradiol on ultrastructure of chromatin in the endometrium and hormone-dependent mammary tumors]

After in vivo and in vitro administration of aestradiol, the chromatin of lamb endometrium and of hormone-dependent 7,12-dimethylbenzanthracene Rat mammary tumors is rapidly transformed from a condensed into a diffuse chromatin. A stimulation of 3H leucine incorporation into protein was also observed. These modifications were specific for estrogen receptor ligands and for estrogen responsive tissues. In vitro tamoxifen induced pycnosis. These changes could be used to improve the prediction of hormone dependency of human breast and uterine cancers.     

Prolonged vibration of cutaneous artery: absence of persisting aftereffects

1-3 h after prolonged (3-16 h) vibration (120 Hz, 0.2-0.3 mm amplitude) of rings of canine saphenous arteries there was no significant change in the contractile response to electrical stimulation, exogenous norepinephrine or of neuronal uptake of tritium labeled norepinephrine. These results did not provide evidence for persistent aftereffects of prolonged vibration.