A deficiency in prothoracicotropic hormone transduction pathway during the early last larval instar of Bombyx mori

The prothoracicotropic hormone (PTTH) is an insect cerebral peptide that stimulates the prothoracic glands to produce ecdysteroids that initiate moulting and metamorphosis. During the last larval instar of holometabolous insects, a reduction in the hemolymph juvenile hormone (JH) levels is a necessary step in initiating larval-pupal transformation. Recently we have demonstrated that very low ecdysteroid levels in the early last larval instar of Bombyx mori initiate the complete inactivation of corpora allata (CA). Results presented here further indicate that PTTH signal transduction pathways undergo specific developmental changes, with a deficiency in transduction in prothoracic gland cells occurring during the early last instar. Glands from the early last instar showed no increase in either cAMP levels or steroidogenesis to the stimulation of PTTH, indicating the absence of the PTTH receptors in gland cells. We propose that this absence of PTTH receptors plays a critical role in directing larval-pupal transformation.     

温胃舒冲剂对小鼠慢性萎缩性胃炎的保护作用及其机理初探

温胃舒冲剂是根据临床实践组成的中药复方制剂．为了探讨其作用机理．用小鼠造成３种模型：去氧胆酸钠（ＤＯＣＡ）造成慢性萎缩性胃炎（ＣＡＧ）模型；ＤＯＣＡ＋甲疏基咪唑造成 ＣＡＧ－阳虚模型，ＤＯＣＡ＋甲状腺＋利血平造成 ＣＡＧ－阴虚模型。以血浆中环磷酸腺苷（ｃＡＭＰ ）、环磷酸鸟苷（ｃＧＭＰ）观察其治疗作用。结果表明，温胃舒能降低ＣＡＧ模型小鼠的ｃＡＭＰ、ｃＧＭＰ．也能降低ＣＡＧ－阳虚模型小鼠的ｃＧＭＰ，与模型对照组比较均Ｐ＜０．０５～０．０１。此外．结果还表明温胃舒冲剂有镇痛、抗炎和抑制胃肠推进运动、并能提高大鼠淋巴细胞转化率、血清ＩｇＧ水平。     

ARE THE STRUCTURAL CHANGES IN ADULT DROSOPHILA MUSHROOM BODIES MEMORY TRACES? STUDIES ON BIOCHEMICAL LEARNING MUTANTS

The pre-imaginal development of Drosophila mushroom bodies is under the influence of an unknown variable which causes populations of wild-type flies at eclosion to differ in the average number of Kenyon cell fibers. During the first week of adult life the number adjusts to an intermediate level which depends upon the experience of the flies. Under olfactory deprivation or social isolation it reaches a lower level than under favorable rearing conditions (J. Neurogenet., 1 (1984) 113–126). The biochemical learning mutants dunce and rutabaga show no experince-dependent modulation of fiber number (Fig. 2). In both strains the mushroom bodies of young adults seem to develop abnormally; in dunce a loss of aboout 600 fibers is observed, in rutabaga fiber number is low at eclosion and does not increase (Fig. 1a). The following model for long-term memory is proposed: in mushroom bodies outgrowth and decay of Kenyon cell fibers occur simultaneously. The fibers randomly form transient synapses onto extrinsic output neurons of the mushroom bodies and receive synapses from modulating neurons. Experience consolidates certain synapses, thus prolonging survival of the respective Kenyon cell fibers and increasing the steady state level of fiber number (Fig. 3).     

Stimulating PACα Increases Miniature Excitatory Junction Potential Frequency at the Drosophila Neuromuscular Junction

Abstract: Photoactivated adenylate cyclase alpha (PACα) is a light-activated adenylate cyclase that was originally cloned from the eye spot of the protozoan Euglena gracilis. PACα has been shown to rapidly increase intracellular cyclic adenosine monophosphate (cAMP) in vivo in Xenopus oocytes and HEK293 cells, increase the spike width in Aplysia sensory neurons, and modify behavior in Drosophila. Using the GAL4 UAS system, we heterologously expressed PACα in motorneurons and quantified the effects of its activation at the neuromuscular junction of the Drosophila third instar wandering larva, a well-characterized model synapse. By recording from body-wall muscle 6, we show that the presynaptic activation of PACα with blue light significantly increased miniature excitatory junction potential (mEJP) frequency in the presence of calcium with a delay of about 1 minute. Similar effects have been observed in previous studies that utilized adenylate cyclase agonists (Forskolin) or membrane-permeable cAMP analogs [dibutyryl cAMP and 4-chlorophenylthio-(CPT)-cAMP] to increase presynaptic cAMP concentrations. PACα′s efficacy in combination with its specificity make it an invaluable tool for the rapid regulation of cAMP in vivo and for investigating the mechanisms by which cAMP can modulate synaptic transmission and neuronal plasticity in Drosophila.     

磁场对AMI大鼠心肌ATP及血浆cAMP、cGMP的影响

目的探讨磁场对AM I的保护作用。方法将大鼠随机分为5组即:空白对照组、磁场对照组、AM I组、AM I药物(心得安)治疗组和AM I磁场治疗组。采用虫荧光素酶法及放射免疫技术法对实验性大鼠进行心肌ATP含量、及血浆cAMP、cGMP的测定。结果AM I磁场治疗组心肌ATP明显高于AM I组(P<0.01)与药物治疗组相近似。AM I的血浆cAMP、cGMP含量明显高于空白对照组(P<0.01)及磁场对照组,AM I磁场治疗组与药物治疗组明显低于AM I组(P<0.01)。结论磁场能降低AM I大鼠cAMP、cGMP的含量,增加心肌ATP含量,对心肌具有保护作用,这也为磁场用于AM I的治疗提供了实验依据。