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Results for “Microinjection”

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PubMedDate not supplied

Use of an oil-hydraulic microinjection pump for subretinal infusions.

The injection of cell suspensions or drugs into the subretinal space is a new promising option of vitreoretinal surgery for the treatment of degenerative retinal disorders. We used a manual oil-hydraulic microinjection pump to subretinally inject suspensions of retinal pigment epithelial cells in Royal College of Surgeons rats and in patients suffering from age-related macular degeneration with geographic atrophy. The histological examination of the treated rat eyes showed that cell suspensions could be placed precisely in the subretinal space. Intra- and postoperative outcome of the patients in the clinical trial revealed no retinal complications during 6 months of follow up. We suggest the oil-hydraulic microinjection pump to be a valuable instrument for controlled and precisely dosed atraumatic infusion or aspiration of small volumes of cell suspensions, fluids or drugs in vitreoretinal surgery.

Animals↗

PubMed2002

Effects of 5-HT1B receptor ligands microinjected into the accumbal shell or core on the cocaine-induced locomotor hyperactivity in rats.

The present study was designed to examine the effect of 5-HT1B receptor ligands microinjected into the subregions of the nucleus accumbens (the shell and the core) on the locomotor hyperactivity induced by cocaine in rats. Male Wistar rats were implanted bilaterally with cannulae into the accumbens shell or core, and then were locally injected with GR 55562 (an antagonist of 5-HT1B receptors) or CP 93129 (an agonist of 5-HT1B receptors). Given alone to any accumbal subregion, GR 55562 (0.1-10 microg/side) or CP 93129 (0.1-10 microg/side) did not change basal locomotor activity. Systemic cocaine (10 mg/kg) significantly increased the locomotor activity of rats. GR 55562 (0.1-10 microg/side), administered intra-accumbens shell prior to cocaine, dose-dependently attenuated the psychostimulant-induced locomotor hyperactivity. Such attenuation was not found in animals which had been injected with GR 55562 into the accumbens core. When injected into the accumbens shell (but not the core) before cocaine, CP 93129 (0.1-10 microg/side) enhanced the locomotor response to cocaine; the maximum effect being observed after 10 microg/side of the agonist. The later enhancement was attenuated after intra-accumbens shell treatment with GR 55562 (1 microg/side). Our findings indicate that cocaine induced hyperlocomotion is modified by 5-HT1B receptor ligands microinjected into the accumbens shell, but not core, this modification consisting in inhibitory and facilitatory effects of the 5-HT1B receptor antagonist (GR 55562) and agonist (CP 93129), respectively. In other words, the present results suggest that the accumbal shell 5-HT1B receptors play a permissive role in the behavioural response to the psychostimulant.

Animals↗

PubMedDate not supplied

[Effects of hypothalamic microinjections of 6-hydroxydopamine (6-OHDA) on estral cycle and morphology of the genital tract in the female rat (author's transl)].

To determine whether central catecholaminergic pathways are involved in the neural contral of gonadotrophin secretion, they were interrupted at the hypothalamic level by microinjections of 6-hydroxydopamine (6-OHDA). The effects on ovulation, estral cycle and ovarian and uterine histology were studied. Microinjections of 50 mug of 6-OHDA hydrobromyde were made bilaterally into the anterolateral hypothalamus in a group of rats. Another group was injected with 25 mug of 6-OHDA, while a control group recieved an equivalent volume (5 mul) of saline with ascorbic acid. Animals injected with 50 mug of 6-OHDA showed blockade of ovulation, vaginal cytology characteristics of persistent estrous, polyfollicular ovaries and enlarged uteri with hypertrophic endometrial glands. In the group injected with 25 mug, similiar effects were demonstrated, but the number of affected animals was smaller than that in the 50 mug group. Control animals dit not show modifications, either in estral cycle or in ovarian and uterine histology. These results suggest that 6-OHDA injected into the anterolateral hypothalmus interferes with catecholaminergic pathways that participate in the neural control of ovulation.

Animals↗

PubMed1999

[Studies on microinjection of mouse spermatozoa into rabbit oocytes].

The methods of intracytoplasmic sperm injection (ICSI) and subzonal injection (SUZI) were used to study heterologous fertilization and embryonic development between the mouse and the rabbit. Results were as follows: 1. The mouse sperm nuclei decondensed and formed pronuclei following microinjection into cytoplasm and perivitelline space (PVS) of rabbit oocytes; 2. The hybrid embryos developed to the stage of 8-cell when cultured in vitro; 3. The karyotype analysis showed a normal complement of rabbit oocyte and mouse sperm chromosomes in the 4-cell hybrid embryos; 4. The ultrastructure of 4-cell hybrid embryos was similar to that of normal 4-cell rabbit embryos; 5. The fertilization rate (32.4%) and cleavage rate (22.2%) when 5-10 mouse spermatozoa were injected were higher than those of injection of a single spermatozoon into PVS of the rabbit oocyte, but the difference was not significant (P > 0.05). The fertilization rate (42.3%) and cleavage rate (30.8%) in rabbit oocytes in vitro matured for 11-12 h were higher than those in the oocytes which were in vitro matured for 24-25 h following microinjection of 1-2 mouse spermatozoa into PVS, but the difference was not significant (P > 0.05).

Animals↗

PubMedDate not supplied

Activation of the renal sympathetic nerve by leptin microinjection into the ventromedial hypothalamus in rats.

Leptin produced in white adipose tissue activates sympathetic nerve activity via the ventromedial hypothalamus (VMH) within the central nervous system (CNS). Using an electrophysiological technique, we investigated whether direct microinjection of leptin into the VMH elevates renal sympathetic nerve activity (RSNA) and blood pressure (BP) in anesthetized rats. Microinjection of leptin (100 ng/microL) into the VMH caused significant activation of RSNA from 25 minutes after administration but no affect on BP. We concluded that leptin-induced elevation of RSNA is mediated via the VMH or its vicinity within the CNS.

Animals↗

PubMed1992

[Cardiovascular effects of microinjection of neuropeptide Y into lateral septal nucleus].

Cardiovascular effects of microinjection of neuropeptide Y (NPY) into the lateral septal nucleus (LS) were investigated in anaesthetized rats. The microinjection gave rise to a significant increase in blood pressure and heart rate. The pressure response was dose-dependent but the tachycardia was not. Control injection of 0.9% saline into LS produced no haemodynamic response.

Animals↗

PubMed2003

[Whole amount in situ hybridization and transgene via microinjection in zebrafish].

Zebrafish is new model organism to study development of the vertebrate. In this report, we chose a fragment of gene GATA-1 which specifically expressed in zebrafish hematopoiesis system as probe to carry on whole amount in situ hybridization. Then we transported reporter gene driven by GATA-1 promoter into the embryos via microinjection approach and observed the spatial and temporal expression pattern of GFP. Our results demonstrated that efficient and reliable technology of whole amount in situ hybridization and microinjection in zebrafish was established.

Animals↗

PubMedDate not supplied

Expression of reporter genes introduced by microinjection and electroporation in fish embryos and fry.

The technique for foreign gene transfer in fish is becoming a novel method for genetic engineers to produce useful transgenic fish as well as for experimental purposes. Our studies of transgenic fish have been focused on methods of gene transfer and regulatory elements for transgene expression. I describe the characteristics of 3 gene transfer methods we have established (i.e., microinjection into fertilized eggs, microinjection into oocytes, and electroporation). Also described is a series of experiments to estimate activities of several promoters and enhancers in a fish cell line. Finally, experiments to examine activities of the elements shown to be active in the cell line in fish embryos and fry are described. SV2, miw, and metallothioneine promoters of trout and mouse were shown to be active in these experiments.

Animals↗

PubMed1991

Single cell assay with an automated capillary microinjection system.

An automated capillary microinjection system with computer controlled positioning of the cells and of the capillary, and its applications and advantages are described. About 1500 injections are possible in one hour, with high reproducibility. In cytoplasmic and nuclear injections more than 90% and 85% of the cells are successfully injected. Using FITC-Dextran at a concentration of 0.5% as a fluorescently labelled coinjection marker, 99% of the cells can be retrieved in culture medium even 48 hours after injection. The coordinates of the cells are stored in the computer and accuracy in statistical evaluation of experiments is improved in comparison to the manual techniques. Methods for preparation and handling of glass capillaries were developed resulting in reproducible form and significantly reduced clogging rate. The improved characteristics offered by this system are demonstrated in studies leading to the confirmation of existence of mRNA(s) inhibiting cell proliferation. Functional screening by cell injections of cDNA libraries and of size fractionated mRNA molecules can be performed efficiently with the automated microinjection system.

Animals↗

PubMed1992

Effects of microinjection of picrotoxin into posterior hypothalamus on ventricular electric stability.

Ventricular fibrillation threshold (VFT), serum potassium, and monophasic action potentials (MAP) have been assessed before and after microinjection of picrotoxin (Pic) into posterior hypothalamus in rabbits. Pic (2 and 3 micrograms) brought about a biphasic effect on VFT, an initial decrease followed by a notable increase. Pretreatment with spinal cord transection almost abolished the descending phase, whereas pretreatment with vagotomy depressed the ascending phase significantly. Following the microinjection of Pic, serum potassium rose up to 5.0 mmol.L-1 at 30 min. The amplitude of MAP (MAPA) and Vmax were lessened in rabbits, while in vagotomized rabbits, the changes of MAP were aggravated, and the duration of MAP was shortened. Phentolamine counteracted the changes of MAP induced by Pic. These results suggested that the initial decrease of VFT caused by Pic derived mainly from the direct action and myocardial ischemia of sympathetic activation, while its subsequent elevation was caused by vagal activation and hyperkalemia.

Action Potentials↗

PubMed2003

[Microinjection of L-NAME into dorsal raphe nucleus inhibits nociceptive response in sigmoid pain model of rats].

By means of Fos immunocytochemistry, nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and microinjection methods, the role of nitric oxide synthase (NOS) of dorsal raphe (DR) neurons in the modulation of rats sigmoid pain was studied. The results showed: (1) Rats exhibited aversive behavioral responses related to visceral pain after injecting formalin into the sigmoid wall. NOS neurons in DR were up-regulated, in addition, about 8% of NOS-labeled neurons were Fos positive. By contrast, there were no Fos/NOS double-labeled neurons in the control group. (2) Formalin-induced sigmoid pain scores and the expression of Fos in the spinal cord at S1 segment were decreased after microinjecting L-NAME into the DR. These findings suggest that NOS neurons are involved in the modulation of formalin-induced sigmoid pain and that NO may play an important role in the transmission of visceral nociceptive message in the midbrain.

Analgesics↗

PubMed2003

Noninvasive fluorescent screening of microinjected bovine embryos to predict transgene integration.

Most transgenic domestic animals are generated by direct microinjection of DNA fragments into zygote pronuclei. It has generally been assumed that the majority of integration events should occur prior to the first round of chromosomal DNA replication. The aim of this study was to investigate the expression of GFP in bovine preimplantation embryos by using a gfp reporter gene consisting of chicken beta-actin promoter, the CMV-IE enhancer, gfp cDNA (EGFP) (732 bp) and rabbit beta-globin polyadenylation sequences. In five experiments 302 bovine zygotes were injected while 75 served as a control. The fluorescence intensity was detected at 72 and 168 h following fertilization in bovine embryos injected with 3 ng/microl in experiments 1-3, and injected with 5 ng/microl in experiments 4-5. Eight embryos were considered as expressing green fluorescence protein; 2 of them were 100% fluorescent after microinjection of a higher dose of the DNA; one was 75%, two--50%, and three 25% transgenic. The mosaicism was assumed to be at 75%. The results indicated that the fluorescence could be analyzed at any time of bovine embryo development. It was therefore concluded, that chicken beta-actin promoter together with the CMV-IE enhancer would confer a strong expression of the gfp reporter gene in preimplantation bovine embryos. Therefore, using GFP that could be simply detected in live bovine (transgenic) embryos would be very promising in establishing transgenic lines of domestic animals producing in their fluids human therapeutic proteins.

Animals↗

PubMed2004

Production of functional transgenic mice by DNA pronuclear microinjection.

Successful experiments involving the production of transgenic mice by pronuclear microinjection are currently limited by low efficiency of random transgene integration into the mouse genome. Furthermore, not all transgenic mice express integrated transgenes, or in other words are effective as functional transgenic mice expressing the desired product of the transgene, thus allowing accomplishment of the ultimate experimental goal--in vivo analysis of the function of the gene or gene network. The purpose of this review is to look at the current state of transgenic technology, utilizing a pronuclear microinjection method as the most accepted way of gene transfer into the mouse genome.

Animals↗

PubMed2004

[Effect of microinjections of a selective blocker of M1-muscarinic receptors pirenzepine into the neostriatum on the rat motor activity].

In simulated discrimination conditioned reflex of active avoidance (CRAA) in T-maze, the effect of bilateral microinjections of the muscarinic receptor M1 selective blocker pirenzepine on the CRAA formation and behaviour in the "open filed" test, was studied in rats. A sharp worsening of the CRAA learning and a significant increase in the motor activity were shown to occur in rats following the microinjections as compared with control rats. The change in the motor responses seems to account for the worsening of the CRAA learning. Another reason of the phenomenon could involve a disorder in perception of conditioned signals and their poor differentiation. The data obtained and the literature data suggest a complex character of changes induced by the blockade of the M1 muscarinic receptors of the neostriatum.

Animals↗

PubMed2004

[Effects of neurotensin microinjected into ventral tegmental area on spontaneous motor activity in neonatal 6-hydroxydopamine-treated rats].

Intracerebroventricular treatment of the catecholamine neurotoxin, 6-hydroxydopamine (6-OHDA) after desmethylimipramine pretreatment results in semipermanent brain dopamine (DA) depletion. It has been shown that rats neonatally treated with 6-OHDA show hyperactivity in an open-field test. The purpose of this study was to investigate the spontaneous motor activity in neonatal 6-OHDA-treated rats following bilateral saline (SAL; 0.25 microliter) or neurotensin (NT; 1.25, 2.50, 5.00 micrograms/0.25 microliter/side) microinjection into the ventral tegmental area. Each dose of NT significantly augmented locomotor activity in 6-OHDA-treated rats. On the other hand, controls did not show significant increase in lower dose of NT. Effect of NT microinjection on number of rearings in the 6-OHDA-treated group was not significantly altered compared to the vehicle-treated group. These results suggest that the responses in locomotor activity to NT the ventral tegmental area increase in neonatal 6-OHDA-treated rats, and imply that residual activity in mesolimbic DA neurons which is mediated by NT receptors contributes to a part of the hyperactivity seen after neonatal 6-OHDA lesion.

Animals↗

PubMed2003

[Expressions of c-fos in different brain regions after microinjection of 5-HT3 receptors agonist in hippocampus].

AIM: To explore the neuronal circuit and possible pathway related to the 5-HT3 receptors in hippocampus neuroimmunomodulation. METHODS: SABC immunocytochemical staining was used to detect the c-fos expression. RESULTS: A large number of FOS-positive neurons expression were found in the hippocampus and brain cortex at 1 hour after microinjection of 5-HT3 receptor agonist (I-PBG) in the hippocampus, but as time went on, the number of FOS positive-neurons gradually decrease. A small number of FOS positive-neurons were found only in the hypothalamus and gray matter around acqueduct of midbrain, respectively at 8 and 16 hs after injection of 1-PBG. The expression of c-fos induced by 1-PBG could be blocked by pre-microinjection of tropisetron. CONCLUSION: Brain cortex-hippocampus hypothalamus-gray matter around acqueduct of midbrain forma neuronal network, which may be related to immunomodulation.

Animals↗

PubMed2005

[Effect of microinjection of atrial natriuretic peptide into the paraventricular nucleus on baroreflex sensitivity in conscious rats].

The role of atrial natriuretic peptide (ANP) in the central regulation of the circulation is known to be a neurotransmitter or a neuromodulator, but its actions on baroreceptor reflex function are not fully resolved. The present study examined the role of ANP (6, 60 ng/0.2 microl) by direct microinjection into the hypothalamic paraventricular nucleus (PVN) in conscious rats. OPC-21268 (0.45 microg/3 microl), an antagonist of the V(1) receptor, was microinjected into the lateral ventricle to examine whether the effect of ANP on baroreflex sensitivity is mediated by vasopressin (VP). ANP significantly increased the baroreflex sensitivity, and OPC-21268 attenuated the increase of baroreflex sensitivity induced by ANP. Intravenous injections of ANP (60 ng/0.04 ml) did not affect baroreflex sensitivity. These results suggest that ANP in the PVN may produce a facilitative effect on baroreflex, and the effect may be via, at least in part, the central vasopressin.

Animals↗

PubMed1991

[Changes in the synaptic release of catecholamines in the rat striatum with multiple microinjections into it of fenamine and haloperidol].

The dopamine (DA) and noradrenaline (NA) levels of the synapses of the rat rostral striatum was studied with the aid of radioenzymatic and microdialysis techniques. Two weeks after the starting of 45 g amphetamine daily intrastriatal microinjections, the level of DA was 3-5-fold higher than in the control whereas NA level still was unchanged. The next amphetamine injection did not potentiate the synaptic DA level whereas NA level was increased. In contrast to behavioral deviation (the avoidance conditioning lost), the haloperidol intrastriatal microinjections did not affect the DA synaptic level in rostral neostriatum.

Amphetamine↗