中国成都地区汉族人群DHFRP2位点的遗传多态性研究

用扩增片断长度多态性技术分析短串联重复序列（STR）DHFRP2位点的DNA多态性, 在156个中国成都地区汉族无关个体中发现6个等位基因,19种基因型,并首次发现一重复单元数不是4的整数倍的等位基因,该等位基因按孟德尔遗传规律遗传。观察的基因型分布符合Hardy-Weinberg定律,其个人鉴别力（DP）为0.87,杂合度为67.3%,多态性信息量（PIC）为0.68,非父排除率（CE）为45.5%,家系分析结果表明, 该位点符合孟德尔遗传法则。 Abstract：　Analyzes polymorphism of short tandem repeat locus (DHFRP2) by using Amp-FLP. Six alleles and nineteen genotypes were observed in 156 unrelated individuals of Chinese Hans in Chengdu. Meanwhile, we first discovered a new allele, its repeat monomers is not integral times of four, which is in conformity with Mendelian inheritance. The allelic discriminating power (DP), observed heterozygocity (h), polymorphism information content (PIC) and chances of paternity exclusion (CE) are 0.87, 67.3%, 0.68 and 45.5% respectively. The distribution of its genotypes tally with Hardy-Weinberg equilibrium and family study manifested that the locus is in conformity with medelian inheritance.     

The position of integration affects expression of the γ-globin-encoding gene linked to HS3 in transgenic mice

Proper expression of the human β-globin (βGlb) locus is dependent on the presence of a major regulatory element located upstream from the βGlb gene cluster, the locus control region (LCR). The LCR, as well as the individual DNase-I-hypersensitive sites from which it is composed, have been shown to provide position-of-integration-independent expression in transgenic mice. Here, we report that a transgenic founder carrying multiple integrations of a hypersensitive site 3::^Aγ globin gene (HS3::^Aγ) construct produced three types of progeny, one with zero ^Aγ expression in the adult stage, one with minimal ^Aγ expression (1% of ^Aγ-expressing cells) and one with abundant ^Aγ expression (100% ^Aγ-expressing cells). The possibility that these phenotypes were due to parental imprinting or to DNA rearrangements of the transgene or to point mutations of the HS3 core or the ^Aγ promoter were excluded. The pattern of inheritance of the three HS3::^Aγ transgene phenotypes indicate that the transgene has integrated into three different chromosomes. These results provide direct evidence that the HS3 of the LCR is not sufficient to protect the ^Aγ gene from position effects excerted by the surrounding chromatin.     

Use-Dependent Suppression of the Nicotinic Acetylcholine Receptor Response by the Proadrenomedullin N-Terminal 20-Amino Acid Peptide in Rat Locus Coeruleus Neurons

Abstract: The effects of the proadrenomedullin N-terminal 20-amino acid peptide (PAMP) on the nicotinic acetylcholine (ACh) receptor (nAChR)-mediated inward current were investigated in neurons acutely dissociated from the rat locus coeruleus using whole-cell recording under voltage clamp. Nicotine and cytidine mimicked the ACh response, whereas the maximal response to dimethyl-phenylpiperazinium was lower in amplitude compared with that to ACh. Nicotine-induced current ( I _nic) was suppressed more effectively by mecamylamine than by hexamethonium. In addition, neither atropine nor α-bungarotoxin affected the I _nic. PAMP reversibly and noncompetitively suppressed the peak amplitude of 10⁻⁴ M I _nic. PAMP concentrations for the threshold, half-maximal inhibition, and maximal inhibition of 10⁻⁴ M I _nic were 10⁻⁸, 2.6 × 10⁻⁷, and 10⁻⁵ M , respectively. The peak amplitudes of 10⁻⁴ M I _nic elicited at 2-min intervals showed a gradual decline in the presence of 10⁻⁷ M PAMP. This decline in the I _nic was independent of the period of PAMP pretreatment. The suppression of I _nic by PAMP did not show any voltage dependency at a holding potential ( V _H) of <0 mV, although the inhibitory effect was masked by the marked inward rectification of I _nic at a V _H of 0 mV. These results suggest that PAMP could thus be a unique endogenous peptide that antagonizes the nAChR in the CNS.     

Direct Transfer into Nitrocellulose and Quantitative Radioautographic Anatomical Determination of Brain Tyrosine Hydroxylase Protein Concentration

An improved quantitative immunochemical determination of brain tyrosine hydroxylase (TH) concentrations was designed using direct transfer into nitrocellulose from 20-microns thick brain sections, followed by immunodetection and quantitative radioautography in three reference brain structures (locus ceruleus, substantia nigra, and ventral tegmental area). Results obtained by this methodology were similar to those obtained after extraction and Western blotting of the TH protein in control and reserpine-treated animals. Moreover, this methodology allows the combination of high sensitivity and high anatomical resolution in the study of the distribution of pharmacological effects. The locus ceruleus exhibited a significant posteroanterior distribution of TH protein concentration in control and reserpine-treated animals.     

Studies on synaptic transmission in spinal cord cultures: a comparison of postsynaptic actions of classical neurotransmitters with the peptides

The postsynaptic action of the classical neurotransmitter noradrenaline (NA), the reversal potential of the excitatory postsynaptic potential (EPSP) and the effects of divalent cations on EPSPs in dissociated spinal cord cultures are described. In co-cultures of locus coeruleus explant and spinal cord cells, it was found that NA could mimic the response evoked by stimulation of the explant on the spinal cord cells surrounding the explants. Both depolarization and hyperpolarization responses were observed. On a few occasions, a biphasic response consisting of a hyperpolarization followed by a depolarization was observed. The depolarizing response was associated with an increase in input resistance of the membrane. This would suggest that NA may have a facilitatory effect on synaptic transmission. The depolarizations were antagonized by the α-antagonist piperoxane, and were not affected by the β-antagonist propranolol at the concentrations tested, indicating that the receptor mediating these responses is of the α-type. The reversal potential for dorsal root ganglion and spinal cord cells was +8±3.2 mV (mean±s.e.m.), and that for spinal cord and spinal cord cells was ?4±4.3 mV (mean±s.e.m.). These values are different from those previously reported for glutamate in spinal cord cultures. The effects of high and low concentrations of calcium ions on quantal output and mean quantal amplitude or quantal size of the EPSP were further examined. As expected, the cation had an effect mainly on the release process: increasing the concentration of calcium increased the amount of neurotransmitter released, while reducing the concentration of calcium reduced release. Quantal size was slightly or not affected by alteration of external calcium. In comparing the postsynaptic actions of classical neurotransmitters to those of peptides, there is apparently no evidence that the actions of the two groups of agents on central neurons are different. It appears, however, that the peptides generally elicit responses at lower concentrations than the classical neurotransmitters. Further experimentation is required to fully elucidate the actions of peptides on mammalian central neurons.     

Quantitation of fiber growth in transplanted central monoamine neurons

Summary Nerve fiber production by central noradrenaline (NA), dopamine (DA), and 5-hydroxytryptamine (5-HT) neurons was studied using immature brain tissue containing locus coeruleus, substantia nigra, or ventro-caudal medulla oblongata respectively, homologously grafted to the anterior chambers of rat eyes. A method was developed for quantitation of the fiber growth that occurs on the sympathetically denervated host irides as observed in whole mounts using Falck-Hillarp fluorescence histochemistry and by the uptake of ³H-metaraminol into the irides. Survival and growth in oculo of the three different areas were characterized by direct observations through the cornea in vivo for a number of pre- and postnatal stages of development of the donors, and the findings correlated to the degree of monoamine nerve fiber production on the host irides. The growth of fetal locus coeruleus transplants on irides was quantified using both fluorescence microscopical measurements of innervated areas and uptake of ³H-metaraminol. The uptake was well correlated to the histochemical measurements on individual irides, thus validating the fluorescence microscopical measurements of fiber production. The fiber growth of fetal locus coeruleus grafts on irides was followed for 20 weeks. The nerves increased in number and uptake capacity approximately linearly for 6 weeks whereafter the increase rapidly levelled off. On average, the final amount of nerve production by fetal locus grafts did not cover more than 1/3 of the host iris surface, and the average uptake of ³H-metaraminol by these nerves did not exceed 60% of that found in sympathetically intact control irides. The locus grafts produced a similar amount of fluorescent fibers in the host iris independent of the crown-rump length stage of the donor fetus and the final size of the transplants in oculo.The survival and growth of NA, DA and 5-HT neurons grafted from various postnatal donor rats was also followed by fluorescence microscopy. Locus coeruleus grafts produced markedly more fibers than the two other types of grafts when the donor was one week old or less, and DA grafts produced the least fibers of the three. Even from one month old donors some MA neurons survived grafting. Also, using prenatal donars, the locus coeruleus grafts produced many more fibers on the irides than did the DA grafts. It was concluded that the intraocular transplantation technique is very suitable for quantitative studies of nerve fiber production by immature monoamine neurons, and that it should be possible to study many other neuron systems in similar ways with this technique.Supported by the Swedish Medical Research Council (04X-03185), Magnus Bergvalls Stiftelse and Karolinska Institutets Fonder. The skilful technical assistance of Miss Ingrid Strömberg, Miss Maud Eriksson and Miss Gerd Boëtius is gratefully acknowledged. Thanks are due to Swedish Pfizer for the generous supply of Nialamid^®     

Identification of complement 5a-like receptor (C5L2) from astrocytes: characterization of anti-inflammatory properties

Brain inflammation is regulated by endogenous substances, including neurotransmitters such as noradrenaline (NA), which can increase anti-inflammatory genes. To identify NA-regulated, anti-inflammatory genes, we used TOGA (total gene expression analysis) to screen rat astrocyte-derived RNA. NA-inducible cDNA clone DST11 encodes an isoform of the complement C5a receptor (C5aR), with 39% identity at the amino acid level to the rat C5aR, and 56% identity to a recently described human C5aR variant termed C5L2 (complement 5a-like receptor). Quantitative PCR confirmed that in astrocytes, DST11 mRNA expression is increased by NA, whereas in vivo depletion of cortical NA reduced DST11 levels. Western blot analysis demonstrated basal and NA-induced expression of DST11 as a 45 kDa protein in primary astrocytes cultures. Immunocytochemical staining of adult rat brain revealed DST11-immunoreactivity throughout brain, co-localized to neurons and astrocytes. In astrocytes, induction of nitric oxide synthase type 2 was increased by treatment with antisense oligonucleotides to DST11. Reducing DST11 expression also increased nuclear factor kappaB reporter gene, and decreased cAMP response element reporter gene activation. These results demonstrate that DST11 is a C5aR isoform expressed by glia and neurons, which is regulated by NA, and exerts anti-inflammatory functions. Changes in DST11 levels in diseased brain could therefore contribute to the progression of inflammatory damage.     

Participation of galaninergic neurotransmission at the paraventricular hypothalamic nucleus in the suppression of baroreceptor reflex response by locus ceruleus in the rat

We evaluated the potential participation of galanin (GAL) at the paraventricular nucleus of hypothalamus (PVN) in the suppression of baroreceptor reflex (BRR) response by locus ceruleus (LC), using adult male Sprague-Dawley rats anesthetized with pentobarbital sodium. Microinjection of GAL (100 pmol) bilaterally into the PVN significantly depressed the BRR response. This suppressive effect was appreciably antagonized when GAL (100 pmol) and GAL antiserum (1:20) were coadministered into the bilateral PVN. Whereas bilateral microinjection of GAL antiserum into the PVN by itself elicited minimal effect, it nevertheless significantly attenuated the suppressive effect of either electrical or chemical activation of LC on the BRR response. Pretreatment with the same amount of normal rabbit serum (1:20), on the other hand, was ineffective. These results suggest that a galaninergic projection from the LC to PVN may participate in the suppression of BRR response by this dorsal pontine nucleus.     

Monoamine Metabolism in the Locus Coeruleus Measured Concurrently with Behavior During Opiate Withdrawal: An In Vivo Microdialysis Study in Freely Moving Rats

Abstract: Using microdialysis, changes in monoamine metabolism were monitored in the locus coeruleus of freely moving rats during opiate withdrawal concomitantly with behavioral symptoms. Rats were infused with morphine (2 mg/kg/h, s.c.) or saline for 5 days and challenged with naltrexone (100 mg/kg, s.c.) on day 6. Following naltrexone challenge, the classic behavioral symptoms of morphine withdrawal were observed in rats treated with morphine but not in saline-infused rats. In morphine-dependent rats, naltrexone induced a marked increase (280%) in dialysate concentrations of 3,4-dihydroxyphenylacetic acid, an index of the functional activity of the noradrenergic neurons in the locus coeruleus. The local concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid were also increased (70%) during morphine withdrawal. Taken together, these results (a) confirm in unanesthetized rats the hypothesis of an activation by opiate withdrawal of noradrenergic neurons in the locus coeruleus and (b) suggest an increase in serotonergic transmission in the same nucleus during morphine withdrawal.     

Elevated Tyrosine Hydroxylase in the Locus Coeruleus of Suicide Victims

Abstract: The amounts of tyrosine hydroxylase protein in locus coeruleus from nine pairs of antidepressant-free suicide victims and age-matched, sudden-death control cases were determined by quantitative blot immunolabeling of cryostat-cut sections from the caudal portion of the nucleus. In each of the nine age-matched pairs, the concentration of tyrosine hydroxylase was greater in the sample from the suicide victim, with values ranging from 108 to 172% of the matched control value (\-x = 136%). By contrast, there were no differences in the concentrations of neuron-specific enolase protein in the same set of samples. Similarly, the number of neuromelanin-containing cells, counted in sections of locus coeruleus adjacent to those taken for blot immunolabeling analyses, did not differ between the two groups. These data indicate that locus coeruleus neurons from suicide victims contain higher than normal concentrations of tyrosine hydroxylase, thus raising the possibility that the expression of tyrosine hydroxylase in locus coeruleus may be relevant in the pathophysiology of suicide.