Methionine and leucine enkephalin in rat neurohypophysis: different responses to osmotic stimuli and T2 toxin

Specific radioimmunoassays were used to measure the effects of hypertonic saline (salt loading), water deprivation, and trichothecene mycotoxin (T2 toxin) on the content of methionine enkephalin (ME), leucine enkephalin (LE), alpha-neoendorphin, dynorphin A, dynorphin B, vasopressin, and oxytocin in the rat posterior pituitary. Concentrations of vasopressin and oxytocin decreased in response to both osmotic stimuli and treatment with T2 toxin, but the decrease was greater with osmotic stimulations. Similarly, concentrations of LE and dynorphin-related peptides declined after salt loading and water deprivation; LE concentrations also decreased after treatment with T2 toxin. The concentration of ME decreased after water deprivation, did not change after salt loading, and increased after T2 toxin treatment. The differentiating effects of these stimuli on the content of immunoreactive LE and ME are consistent with the hypothesis that LE and ME may be localized in separate populations of nerve endings with different roles in the posterior pituitary.     

Dynorphin and vasopressin: common localization in magnocellular neurons

The opioid peptide dynorphin is widely distributed in neuronal tissue of rats. By immunocytochemical methods, it was shown previously that dynorphin-like immunoreactivity is present in the posterior pituitary and the cells of the hypothalamic neurosecretory magnocellular nuclei which also are responsible for the synthesis of oxytocin, vasopressin, and their neurophysins. By using an affinity-purified antiserum to the non-enkephalin part of the dynorphin molecule it has now been demonstrated that dynorphin and vasopressin occur in the same hypothalamic cells of rats, whereas dynorphin and oxytocin occur in separate cells. Homozygous Brattleboro rats (deficient in vasopressin) have magnocellular neurons that contain dynorphin separate from oxytocin. Thus dynorphin and vasopressin, although they occur in the same cells, appear to be under separate genetic control and presumably arise from different precursors.     

The opioid peptide dynorphin, circadian rhythms, and starvation

Dynorphin, an opioid peptide whose functions are unknown, is found in brain, pituitary, and peripheral organs. Specific radioimmunoassays were used to measure dynorphin in the hypothalamus and pituitary, during the day and at night, as a function of food and water deprivation. Immunoreactive dynorphin was increased in the hypothalamus and decreased in the pituitary at night. Water deprivation led to more than 50 percent reduction in daytime levels of pituitary dynorphin and concomitant increases in hypothalamic dynorphin.     

Comparison of the distribution of dynorphin systems and enkephalin systems in brain

A study of the anatomical distribution of the endogenous opioid dynorphin in rat brain showed that the peptide is localized in a widespread system with multiple cell groups and projections. This network is revealed by the use of multiple antiserums against dynorphin and can be distinguished from the system containing methionine-enkephalin and leucine-enkephalin, which is mapped by the use of antiserums against the enkephalins and biosynthetically related peptides in the adrenal. It thus appears that the brain contains at least three separate opioid neuronal networks: an enkephalin family with components similar to those found in the adrenal, a beta-endorphin family, and a dynorphin family.     

2,5-dimethoxy-4-methyl-amphetamine (STP): a new hallucinogenic drug

We have assessed the effects in normal control volunteers of 2,5-dimethoxy-4-methyl-amphetamine, the chemical present in the hallucinogenic drug STP, in two independent trials. In low doses, this compound produces a mild euphoria. Doses greater than 3 milligrams may cause pronounced hallucinogenic effects lasting about 8 hours and similar to those produced by hallucinogenic doses of lysergic acid diethylamide, mescaline, and psilocybin. 2,5-Dimethoxy-4-methyl-amphetamine, which is chemically related to mescaline and amphetamine, is about 100 times more potent as a hallucinogen than mescaline and only one-thirtieth as potent as lysergic acid diethylamide. Its psychological effects are not accentuated by chlorpromazine.     

Stereoisomers of N-allylnormetazocine: phencyclidine-like behavioral effects in squirrel monkeys and rats

(+/-)-N-Allylnormetazocine is a benzomorphan opioid with psychotomimetic effects. The pure stereoisomers of this compound, as well as the racemic mixture, were compared to phencyclidine for their behavioral effects on squirrel monkeys and rats trained to discriminate phencyclidine from saline. Dose-response determinations were made for responses to phencyclidine, to a racemic mixture of N-allylnormetazocine, and to the pure levo and dextro isomers of N-allylnormetazocine. In both rats and monkeys, the dextro isomer and the racemic mixture produced dose-dependent responses appropriate for phencyclidine; the levo isomer did not produce the responses appropriate for phencyclidine at any of the doses tested. In both species, the levo isomer was more potent than the dextro isomer in decreasing the rate of responding. Thus racemic N-allylnormetazocine is a mixture of compounds that produce different behavioral effects.     

Thyrotropin-releasing hormone induces rhythmic bursting in neurons of the nucleus tractus solitarius

The nucleus tractus solitarius (NTS) contains neurons that are part of the central neuronal network controlling rhythmic breathing movements in mammals. Nerve terminals within the NTS show immunoreactivity to thyrotropin-releasing hormone (TRH), a neuropeptide that has potent stimulatory effects on respiration. By means of a brainstem slice preparation in vitro, TRH induced rhythmic bursting in neurons in the respiratory division of the NTS. The frequency of bursting was voltage-dependent and could be reset by short depolarizing current pulses. In the presence of tetrodotoxin, TRH produced rhythmic oscillations in membrane potential whose frequency was also voltage-dependent. These observations suggest that TRH modulates the membrane excitability of NTS neurons and allows them to express endogenous bursting activity.     

Benzodiazepine receptor-mediated chemotaxis of human monocytes

Benzodiazepines, which are widely prescribed for their antianxiety effects, are shown to be potent stimulators of human monocyte chemotaxis. The chemotactic effects of benzodiazepine receptor agonists were blocked by the peripheral benzodiazepine receptor antagonist PK-11195, suggesting that these effects are mediated by the peripheral-type benzodiazepine receptor. Diazepam was also active in inducing chemotaxis. Binding studies on purified monocytes revealed high-affinity peripheral benzodiazepine receptors, and the displacement potencies of various benzodiazepines correlated with their relative potencies in mediating chemotaxis. The demonstration of functional benzodiazepine receptors on human monocytes, together with recent evidence of receptor-mediated monocyte chemotaxis by other psychoactive peptides (such as opiate peptides), suggests a biochemical substrate for psychosomatic communication.     

SOME CHEMICAL AND PHARMACOLOGICAL OBSERVATIONS ON "LOW NICOTINE" TOBACCO

Chemical and pharmacological tests have been carried out on a sample of "low nicotine" tobacco. Laboratory tests involving toxicological studies on mice and blood pressure determinations in the dog showed that the toxic and vasopressor effects of the smoke from this tobacco was proportional to the amount of nicotine present and relatively independent of the nornicotine content of the tobacco. On man the smoke from these low nicotine cigarettes produced very much less pronounced effects on blood pressure and pulse rate than that produced by ordinary cigarettes. These results indicate that this type of tobacco is sufficiently low in nicotine to make it practically deserving of much further study.     

马铃薯种薯质量对生长和产量的影响Ⅰ .种薯大小

对影响马铃薯的几个主要因素及相互作用进行研究,结果表明,当播种密度一定时,种薯大小无一例外地显著影响产量,即种薯越大产量越高,而其他因素包括品种、来源、季节和海拔不同程度地影响生长和产量。播种时,单位面积的种薯出芽数调整为相同时,种薯大小对单位面积产量不产生影响。证明了种薯单位面积产生的主茎数对产量起决定性作用,特别是单株结薯较少的品种和秋冬作。     

Inhibition of Plant Microtubule Polymerization in vitro by the Phosphoric Amide Herbicide Amiprophos-Methyl

The phosphoric amide herbicide amiprophos-methyl (APM) produced a concentration-dependent inhibition of taxol-induced rose microtubule polymerization in vitro. Parallel studies on taxol-induced assembly of bovine brain microtubules showed no effect of APM at a concentration ten times that required to give complete inhibition of rose microtubule assembly. The data indicate that (i) APM is a specific and potent antimicrotubule drug and (ii) APM directly poisons microtubule dynamics in plant cells, rather than indirectly depolymerizing microtubules through a previously proposed mechanism involving deregulation of intracellular calcium levels.     

Dynorphin-A-(1-8) is contained within vasopressin neurosecretory vesicles in rat pituitary

Dynorphin-A-(1-8), an opioid peptide widely distributed in the rat central nervous system, is present in vasopressin-containing neurosecretory cells terminating in the neural lobe of the pituitary. Electron microscopic immunocytochemistry reveals that dynorphin-A-(1-8) is contained within the same neurosecretory vesicles as vasopressin and vasopressin-associated neurophysin in the neural lobe of the rat. The results indicate that dynorphin may be released in the pituitary concomitantly with vasopressin during the antidiuretic response.     

Vasoconstriction: a new activity for platelet-derived growth factor

Platelet-derived growth factor (PDGF) is a potent mitogen for vascular smooth muscle cells that has been implicated in the pathogenesis of atherosclerosis. The potential role of PDGF in the altered vasoreactivity of atherosclerotic vessels has been studied through an examination of its effects on contractility in the rat aorta. PDGF caused a concentration-dependent contraction of aortic strips and was significantly more potent on a molar basis than the classic vasoconstrictor peptide angiotensin II. Furthermore, PDGF increased the cytosolic free calcium concentration in cultured rat aortic smooth muscle cells. These observations suggest a new biological activity for PDGF that may contribute to the enhanced vasoreactivity of certain atherosclerotic vessels.     

海带废渣真姬菇发酵产物抗氧化活性研究

为了开发海带废渣资源化利用的新途径,以真姬菇为供试菌株,对海带废渣进行液体发酵,并研究发酵产物的抗氧化活性。结果表明真姬菇能以海带渣为营养基质,进行生长发酵,并产生有效的抗氧化活性物质。抗氧化试剂盒检测显示发酵上清液总抗氧化活性为0.23±0.02 U/mg,比未发酵的海带废渣高43.8%,其发酵产物提取液的总抗氧化活性为0.77±0.01 U/mg,比未发酵的海带废渣高18.5%,且均高于化学抗氧化剂BHT。发酵上清液还具有良好的羟自由基清除能力（EC50=0.43 mg/mL）和一定的超氧阴离子自由基清除能力（EC50=26.02 mg/mL）。分析结果表明发酵过程中产生的抗氧化活性物质主要存在于菌丝体内部,而具有羟自由基清除能力的活性物质则游离于发酵上清液。     

D1 and D2 dopamine receptor-regulated gene expression of striatonigral and striatopallidal neurons

The striatum, which is the major component of the basal ganglia in the brain, is regulated in part by dopaminergic input from the substantia nigra. Severe movement disorders result from the loss of striatal dopamine in patients with Parkinson's disease. Rats with lesions of the nigrostriatal dopamine pathway caused by 6-hydroxydopamine (6-OHDA) serve as a model for Parkinson's disease and show alterations in gene expression in the two major output systems of the striatum to the globus pallidus and substantia nigra. Striatopallidal neurons show a 6-OHDA-induced elevation in their specific expression of messenger RNAs (mRNAs) encoding the D2 dopamine receptor and enkephalin, which is reversed by subsequent continuous treatment with the D2 agonist quinpirole. Conversely, striatonigral neurons show a 6-OHDA-induced reduction in their specific expression of mRNAs encoding the D1 dopamine receptor and substance P, which is reversed by subsequent daily injections of the D1 agonist SKF-38393. This treatment also increases dynorphin mRNA in striatonigral neurons. Thus, the differential effects of dopamine on striatonigral and striatopallidal neurons are mediated by their specific expression of D1 and D2 dopamine receptor subtypes, respectively.     

The Chromosomal Control of Leaf Characteristics of Early-Stage Plants in Wheat （Triticum aestivum L.）

Rapid expansion of leaves of early-stage plants in wheat produced by chromosomal control of characteristics related to rapid expansion of the first six leaves of wheat were investigated using a set of single chromosome substitution lines under two different temperature regimes(TRs).Results from this study indicated that several chromosomes could be responsible for each of the four characteristics studied(including leaf width,leaf length,leaf elongation rate and leaf appearance index)and that different chromosomes may be responsible for the same characteristics at different TRs.Only a small number of substitutions that showed the most significant effects on leaf length were found among those that showed the most significant effects on leaf width,providing further evidence that these two characteristics are likely controlled by different sets of genes.Substitutions 4B,4D,and 5A are among those that were repeatedly detected to having significant effects on different leaf characteristics at the lower-TR and genes residing on these three chromosomes could be homologous.This possibility and its implication are discussed.     

Burns and other skin lesions: microcirculatory responses in man during healing

Morphological changes in the cutaneous microcirculation during wound healing have been studied by capillaroscopy in man. In experimental and accidental burns, abrasions, and lacerations, in addition to the anticipated revascularization by the deeper dermal vessels, a distinctive pattern of response by the surrounding papillary capillaries was consistently observed. This appears to be a general phenomenon in healing of skin lesions and suggests the possibility that a potent capillary-attracting factor may be produced within the injured tissue.     

Similarity of synthetic peptide from human tumor to parathyroid hormone in vivo and in vitro

One mechanism considered responsible for the hypercalcemia that frequently accompanies malignancy is secretion by the tumor of a circulating factor that alters calcium metabolism. The structure of a tumor-secreted peptide was recently determined and found to be partially homologous to parathyroid hormone (PTH). The amino-terminal 1-34 region of the factor was synthesized and evaluated biologically. In vivo it produced hypercalcemia, acted on bone and kidney, and stimulated 1,25-dihydroxy-vitamin D3 formation. In vitro it interacted with PTH receptors and, in some systems, was more potent than PTH. These studies support a long-standing hypothesis regarding pathogenesis of malignancy-associated hypercalcemia.     

Neuromuscular transmission: inhibition by manganese ions

Manzganiese ions. are potent blocking argenits of synaptic transmission at the neuromuscular junction in the frog. The main site of action is the presynaptic nerve terminal, where the ions decr-ease the amount of transmitter liberated by a never impulse. The inihibition produced by manganese is reversible.     

共轭亚油酸生理机制的研究进展

共轭亚油酸（CLA）是一类含有亚油酸各种几何与位置异构体的多不饱和脂肪酸,通过瘤胃微生物氢化作用生成,主要从乳制品等反刍动物食品中获得.动物试验发现CLA能够显著影响机体的能量和脂肪代谢,也能够引起机体的脂肪肝和胰岛素抵抗.因此本文综述了CLA对于动物机体的能量消耗、脂肪细胞的分化及肝脏细胞氧化的作用机制.