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Results for “Microinjection”

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At least 1,297 records · Page 72Linked to original sources

PubMed1990

Microinjection of alpha-toxin from Clostridium novyi type A promotes meiotic maturation in Xenopus laevis oocytes.

Microinjection of purified alpha-toxin into Xenopus laevis oocytes induced meiotic maturation provided insulin was present in the medium. Induction of maturation as indicated by breakdown of the germinal vesicle depended on the amount of intracellular alpha-toxin (with a detection limit of 2 ng/oocyte) and on the concentration of insulin. The hormone concentrations used were inactive when given alone and so was alpha-toxin (1 micrograms/ml) applied from the outside. The results demonstrate an intracellular target for alpha-toxin whereas an extracellular target is apparently lacking in oocytes.

Animals↗

PubMed1984

Microinjection of simian adenovirus SA7 (C-8) DNA into the mouse zygotes: differential distribution of viral DNA in organs.

A simian adenovirus SA7 (C-8) DNA was microinjected into fertilized mouse eggs. Thirty-five mice derived from eggs injected with SA7 DNA were screened for the presence of the adenovirus genome in their liver DNA. Eighteen of these mice contained the virus-specific sequences. SA7 DNA was detected in some tissues, but in all cases, viral sequences were absent from muscle and heart DNA. Viral DNA was inherited by 50-70% of the next generation. One mouse that contained about 1 copy of SA7 DNA per haploid genome has been shown to pass it on to five generations, although the integrated viral DNA sustained a considerable structural change between F1 and F3. RNA analysis in various organs of 12 mice has shown the transcription of SA7 DNA to be very infrequent: only in the kidney of one mouse and in the spleen of another did RNA contain SA7-specific sequences.

Adenoviridae↗

PubMed1988

Inactivation kinetics of horseradish peroxidase microinjected into hepatocytes from mice of various ages.

We have studied degradation of proteins in liver parenchymal cells in culture obtained from mice of various ages. Horseradish peroxidase (HRP) was microinjected into the cells by the hypertonic-hypotonic method of Okada and Rechsteiner (Cell, 29 (1982) 33-41). Rate of inactivation of HRP was examined biochemically. Average functional half-lives of the enzyme were 50 h, 53 h and 75 h in the cells of young (3-8 months old), middle-aged (18-20 months old) and old (28-30 months old) mice, respectively. Thus, half-life of the inactivation of the enzyme in "old" cells was about 50% longer than that in "young" or "middle-aged" cells, suggesting that rate of protein degradation is lowered in senescent animals.

Aging↗

PubMed1977

Self-stimulation of the MFB or VTA after microinjection of haloperidol into the prefrontal cortex of the rat.

Haloperidol, a dopamine receptor antagonist, was microinjected in doses of 12 or 24 microng into the prefrontal cortex of the rat. Its effects on self-stimulation of the ventral tegmental area (VTA) or the medial forebrain bundle (MFB) were examined. It was found that these injections failed to attenuate self-stimulation at either structure. However, when haloperidol was injected into the caudate-putamen complex, a decrease in self-stimulation occurred within these structures. These results suggest that dopamine in the medial prefrontal cortex is not necessarily a part of the neurochemical substrate underlying self-stimulation of the ventral tegmental area or medial forebrain bundle.

Animals↗

PubMed1978

Atonia after carbachol microinjections near the locus coeruleus in cats.

The effect of microinjections of carbachol into the dorsolateral pontine tegmentum on the behaviour of cats is investigated. Injections of small amounts (50 and 500ng) of carbachol into the pontine reticular formation induced muscular atonia in otherwise awake animals. The atonia is not due to cholinergic stimulation of the noradrenergic cells of the locus coeruleus or the dorsolateral pons, since the most effective sites were situated ventrally to the locus coeruleus and alpha- and beta-adrenergic blocking agents did not affect the antonia. The results are discussed in view of the postulated role of the locus coeruleus in paradoxical sleep.

Animals↗

PubMed1979

Facilitation of self-stimulation behavior following intracerebral microinjections of opioids into the ventral tegmental area.

The intracerebral microinjection technique was used to localize sites in the brain where morphine facilitated the self-stimulation rate at hypothalamic electrode sites. Bilateral injections of morphine (2 x 1 microgram) into the ventral tegmental area and substantia nigra produced the strongest enhancement at the shortest latencies. At these sites, bilateral injections of 200 ng of morphine also produced a significant enhancement whereas a dose of 50 ng was below threshold for the rate increasing effect. The enhancement by morphine was effectively antagonized by naloxone (5 mg/kg). When injected bilaterally into the same area, D-Ala2-Met5-enkephalinamide (2 x 1 microgram) also induced a strong enhancement of self-stimulation lasting for 70 minutes. A possible dopaminergic substrate for the opiate induced behavioral stimulation is discussed.

Animals↗

PubMed1979

Partial anxiolytic action of morphine sulphate following microinjection into the central nucleus of the amygdala in rats.

In the social interaction test of anxiety, bilateral microinjections of morphine sulphate (10 microgram) into the central nucleus of the amygdala counteracted the reduction in social interaction normally seen when the test arena is unfamiliar to rats. However, these injections did not counteract the decrease in social interaction that is observed as illuminance of the arena is increased. Morphine injections into the medial site depressed social interaction below the levels shown by control animals. In the open field test, morphine produced a facilitation of peripheral activity when injected into the central nucleus whilst a decrease in rearing was observed following similar injections into the medial nucleus. Overall, these data indicate a partial anxiolytic action of morphine in the central amygdaloid nucleus. Results are discussed in relation to possible differences in opioid peptide innervation of these two amygdaloid nuclei.

Amygdala↗

PubMed1984

Bilateral cannula system for intracranial chemical microinjection in small animals.

An easily constructed and inexpensive bilateral cannula assembly for microinjection of chemicals into neural tissue in small animals is described. It reduces problems sometimes encountered with commercially available units, making it useful in both research and teaching laboratory settings. Suggestions for implant procedures and modifications for use in unique applications are suggested.

Animals↗

PubMed1987

Changes in motor activities induced by microinjections of the selective dopamine agonists LY 171555, quinpirole hydrochloride, and SK&F 38393 into the habenula nucleus.

The effects on behaviour of microinjections into the habenula complex of selective agonists for dopamine D-1 (SK&F 38393) and D-2 (LY 171555) receptors were documented in a holeboard, open-field test. The D-2 agonist reduced grooming responses, locomotor activity and rearing behaviour. In contrast, the D-1 agonist increased rearing and locomotor activity but was without effect on grooming responses. Neither drug produced significant effects on inspective hole exploration. The data extend findings of behavioural consequences of central D-1 receptor activation and provide direct evidence in support of the functional and behavioural importance of intrahabenular dopamine receptor sites. The findings are consistent with suggestions for feedback regulation of habenular efferents to midbrain dopaminergic neurons. Effects of both receptor agonists on some responses but not others indicates potential complex interactions between D-1 and D-2 receptors within the habenula.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1988

Flight behavior induced by microinjection of GABA antagonists into periventricular structures in detelencephalated rats.

Behavioral effects of unilateral microinjections into periventricular structures of bicuculline, a classic GABA-A antagonist, and semicarbazide, a glutamic acid decarboxylase blocker, were studied in detelencephalated rats. These drugs produced a behavioral activation together with jumps. However, the characteristics of this behavioral activation differed as the injections were made in dorsal periaqueductal gray matter or medial hypothalamus. These data show close similarities to those observed with intact animals suggesting that GABA-A receptors are involved in the neural control of expression of flight behavior and functions in an intact manner and possibly independent of influences from forebrain structures. At variance with intact animals, these drugs produced contralateral turning behavior when locally injected into MH, pointing to some kind of inhibitory control exerted by telencephalic structures on the expression of circling behavior from diencephalic regions.

Animals↗

PubMed1989

Comparative studies of locomotor behavior following microinjections of muscimol into various sites in the paramedian tegmentum.

Microinjections of various doses of muscimol into the median raphe nucleus, the dorsal raphe nucleus or the caudal portion of the ventral tegmental area elicited dose-dependent increases in locomotor activity. In contrast, injections into the rostral portion of the ventral tegmental area or the midline pontine tegmentum caudal to the median raphe were ineffective. Lower doses of muscimol were required to produce hyperactivity after injections into the median raphe than after injections into any of the other sites. These findings suggest that the median raphe nucleus is the most sensitive site in the paramedian tegmentum for the elicitation of hyperactivity by muscimol.

Animals↗

PubMed1990

Microinjections of a nicotinic agonist into dopamine terminal fields: effects on locomotion.

Nicotine induces locomotion, a behavior associated with the mesocorticolimbic dopamine system. The present study determined the effects on locomotion of direct microinjections of the nicotinic agonist cytisine into four DA terminal fields were nicotinic receptors have been localized: nucleus accumbens (NAS, n = 20), caudate putamen (CPU, n = 9), olfactory tubercle (OT, n = 8), and medial prefrontal cortex (MPC, n = 12). Male Long-Evans rats were injected with cytisine (0.1, 1, 10 and 100 nanomoles per 0.5 microliters per side) or vehicle through indwelling cannulae, and locomotor activity was recorded during a 60-minute test session; each animal was tested with each dose in counterbalanced order. NAS injections of the three highest doses of cytisine increased locomotion relative to vehicle injections; injections in the CPU, dorsal to the NAS, were ineffective, as were MPC and OT injections. The data support the notion that systemic nicotine may interact with dopaminergic projections to the NAS to produce increases in locomotor activity.

Alkaloids↗

PubMed1991

Catalepsy produced by striatal microinjections of the D1 dopamine receptor antagonist SCH 23390 in neonatal rats.

Systemic injection of the D1 dopamine receptor antagonist SCH 23390 produces catalepsy that is of lesser magnitude in neonatal than in adult rats. The present experiments were conducted in order to determine if SCH 23390 would produce catalepsy in neonatal rats following intrastriatal injection and if the ontogenetic pattern of catalepsy induced by intrastriatal SCH 23390 would be similar to the pattern observed with systemic injections. Rat pups (11 or 28 days of age) were microinjected unilaterally with SCH 23390 (0.2, 1, 5 or 10 micrograms) and tested for catalepsy using the forepaw-on-horizontal-bar test. The results demonstrated that robust catalepsy occurred at both ages following intrastriatal injection and that catalepsy induced by 5 micrograms SCH 23390 was of lesser magnitude in 11-day-olds than in 28-day-olds. A separate study assessed the distribution of [3H]SCH 23390 (5 micrograms) following intrastriatal injection in 28-day-olds. Results of the distribution study indicated that [3H]SCH 23390 was localized primarily within the striatum. Taken together, these results suggest that the striatal mechanisms for catalepsy produced by D1 receptor blockade are present, but not fully mature, in preweanling rat pups.

Age Factors↗

PubMed1992

Wild running elicited by microinjections of bicuculline or morphine into the inferior colliculus of rats: lack of effect of periaqueductal gray lesions.

Bicuculline methiodide, a GABAA receptor antagonist, or a high dose of morphine was injected at the same site within the inferior colliculus (IC) of rats. Both drugs elicited the same behavioral activity (wild running). However, the time course and magnitude of the effects of the two drugs differed. Since the behavioral activation elicited was reminiscent of what was found with microinjections of bicuculline methiodide or morphine into the periaqueductal gray (PAG), we lesioned the PAG in another group of rats. It was found that extensive lesions of the PAG including those extending to the medial part of the superior colliculus did not significantly reduce the wild running.

Animals↗

PubMed1996

Intraseptal microinjection of beta-funaltrexamine blocked a microwave-induced decrease of hippocampal cholinergic activity in the rat.

Acute (45 min) exposure to pulsed (2 microseconds pulse width, 500 pulses per second) 2450-MHz microwaves at a power density of 1 mW/cm2 (whole body specific absorption rate 0.6 W/kg) microwaves caused a decrease in cholinergic activity in the hippocampus of the rat as measured by the sodium-dependent high-affinity choline uptake. Microinjection of beta-funaltrexamine (1 microgram) into the septum before microwave exposure blocked this effect. These data indicate that mu-opioid receptors in the septum mediate a microwave-induced decrease in cholinergic activity in the hippocampus and support our hypothesis that microwaves at a whole body SAR of 0.6 W/kg can activate endogenous opioids in the brain.

Animals↗

PubMed1979

Microinjection of the nonhistone chromosomal protein HMG1 into bovine fibroblasts and HeLa cells.

The nonhistone chromosomal protein HMG1 associated rapidly with the nuclei of HeLa cells and bovine fibroblasts following its introduction into the cytoplasm by red cell-mediated microinjection. A number of non-nuclear proteins, on the other hand, failed to concentrate in HeLa or bovine fibroblast nuclei. Autoradiography of thin sections showed that 125I-labeled HMG1 localized within nuclei, and further established that it remained associated with metaphase chromosomes at mitosis. When uninjected HeLa cells were fused with 125I-HMG1-injected HeLa cells, the labeled molecules equilibrated between nuclei within 12 hr. Similar results were obtained with bovine fibroblasts, indicating that a dynamic equilibrium exists between HMG1 and chromatin within living cells. Electrophoresis of 125I-HMG1 retrieved from HeLa cells or bovine fibroblasts up to 48 hr after injection showed that more than 80% of the molecules were intact. Autoradiographic analysis of cells fixed over a period of several days after injection produced apparent half-lives for 125I-HMG1 of 80 hr in HeLa cells and 100 hr in bovine fibroblasts.

Cell Fusion↗

PubMed1982

Initiation of replication at specific origins in DNA molecules microinjected into unfertilized eggs of the frog Xenopus laevis.

Initiation of DNA replication at specific origins was observed by electron microscopy after microinjection of pXlr11, pXlr14 or Col E1 plasmid DNA molecules into unfertilized eggs of the frog, Xenopus laevis. These results are in apparent contradiction with published reports (Harland and Laskey, Cell 21, 761-771, 1980; Laskey and Harland, Cell 24, 283-284, 1981) that specific origin sites were not used in Xenopus laevis eggs. We suggest that eucaryotic origins exist that both increase the probability of replication of contiguous sequences and determine the site at which replication is most likely to begin.

Animals↗

PubMed1982

Transcription of cloned Xenopus laevis ribosomal DNA microinjected into Xenopus oocytes, and the identification of an RNA polymerase I promoter.

Transcription of a cloned Xenopus laevis ribosomal DNA (rDNA) fragment, microinjected into Xenopus oocytes, is initiated at the in vivo 40S pre-ribosomal RNA (pre-rRNA) site (+/- 2 bp) by RNA polymerase I. An X. laevis RNA polymerase I promoter has been mapped by studying the transcription of in vitro rDNA mutants in the oocyte system. The active promoter lies within the DNA segment beginning 145 bp upstream, and most probably ending 16 bp downstream, from the 40S pre-rRNA initiation site (-145 bp to +16 bp). Furthermore, active promoter elements lie more than 35 bp upstream from the initiation site (-35 bp). The X. laevis RNA polymerase I promoter therefore lies mainly upstream from the 40S pre-rRNA initiation site. Independent deletion of three adjacent rDNA segments lying between -61 and +16 bp reduces promoter activity by a factor of more than 16. The central of these "null" deletions removes an oligo(T)6 motif at -27 bp that is in an analogous position to the Goldberg-Hogness (TATA) box of RNA polymerase II promoters.

Animals↗