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PubMed1986

Cueing effects of amphetamine and LSD: elicitation by direct microinjection of the drugs into the nucleus accumbens.

Two groups of rats were trained to discriminate either d-amphetamine sulphate (AMPH; 1 mg/kg) or d-lysergic acid diethylamide bitartrate (LSD; 0.16 mg/kg). Microinjection of AMPH into the nucleus accumbens elicited a cueing effect which was similar to that of systemically administered AMPH in AMPH-trained animals (ED50 was 0.24 micrograms). Co-injection of (-)-sulpiride (50 or 100 ng) into the accumbens antagonized the effect of a fixed dose of AMPH (1 microgram) which, alone, produced 76% of the systemic AMPH cue effect. Microinjections of AMPH (1-5 micrograms) into either the anterior dorsomedial or the anterior ventrolateral striatum failed to elicit the cueing effect of AMPH. In LSD-trained animals a dose of 1 microgram LSD injected into the accumbens produced 84% of the systemic cueing effect of LSD. These results suggest that dopamine (DA) receptors in the nucleus accumbens are involved in AMPH discrimination. Furthermore, since both classical and atypical antipsychotic drugs block the AMPH cue, the results provide indirect evidence for involvement of mesolimbic DA in antipsychotic drug action.

Amphetamine↗

PubMed1988

Defense reaction induced by microinjections of bicuculline into the inferior colliculus.

Behavioral and autonomic effects of microinjections of bicuculline--a GABA receptor antagonist--into ventral aspects of the inferior colliculus (IC) produced a behavioral activation together with jumps. This activation was similar to escape behavior that has been induced from periventricular structures although it was neither as explosive as that observed from the dorsal periaqueductal gray matter (DPAG) nor as coordinated as that obtained from the medial hypothalamus (MH). In anesthetized rats, microinjection of bicuculline into the IC produced a clear rise in mean arterial blood pressure and in heart rate. These effects reached a maximum after 10 min and subsided within 20 min after injection. GABA receptor blockade in the IC of detelencephalated rats also resulted in escape behavior qualitatively similar to that observed in intact animals. These results suggest that in addition to the central gray and medial hypothalamus, GABA also exerts a tonic inhibitory action on neurons of the IC implicated in the generation or elaboration of aversive responses.

Animals↗

PubMed1989

Microinjection of interleukin-1 into brain: separation of sleep and fever responses.

Interleukin-1 (IL1) and muramyl peptides are somnogenic, pyrogenic, immune response modifiers, Their central nervous system loci of action with respect to sleep and body temperature in rabbits were examined in this study using microinjection techniques. Unilateral microinjection of IL1 into various basal forebrain or brain stem sites resulted in elevated colonic temperatures (Tc), but the duration of slow-wave sleep (SWS) was unchanged compared to results obtained after control injections. Injection of IL1 into posterior hypothalamic areas failed to elicit either sleep or temperature responses. In contrast to these results, injection of either IL1 or muramyl dipeptide into the Aqueduct of Sylvius was followed by enhanced SWS and Tc. These results show that IL1-induced sleep and fever responses can be separated. Somnogenic sites of action for IL1 and muramyl peptides remain unknown.

Animals↗

PubMed1994

Facilitation of self-stimulation of ventral tegmentum by microinjection of opioid receptor subtype agonists.

Intracranial self-stimulation (ICSS) evoked from the ventral tegmental area-substantia nigra (VTA-SN) and lateral hypothalamus-medial forebrain bundle (LH-MFB) was assessed following microinjections of mu (Tyr-D-Ala2-N-Me-Phe4-Gly5ol: DAGO), delta-(D-Ala2, D-Met5)-enkephalin: DADME) or kappa (Dynorphin-B or Rimorphin) opioid receptor subtype agonists or saline into either VTA-SN or LH-MFB. The current intensity was fixed at an optimum level to obtain 60-70% of the maximum asymptotic response rate. DAGO (5 micrograms/0.5 microliters), DADME (2 micrograms/0.5 microliters) or Dynorphin B (0.5 microgram/0.5 microliters) injected into VTA-SN facilitated the self-stimulation rates of VTA-SN by 27%, 32%, and 59%, respectively. These microinjections did not alter the self-stimulation of LH-MFB when effects of these injections were still persisting in VTA-SN. Similar doses of these opioid receptor agonists injected into LH-MFB had no significant effect on the self-stimulation rates of either LH-MFB or VTA-SN. The facilitatory effects of DADME were completely abolished by naloxone (30 mg/kg IP). Taken together, these results suggest that all three opioid receptor subtypes of ventral tegmentum and not of lateral hypothalamus are involved in the electrically evoked self-stimulation of VTA-SN.

Analgesics↗

PubMed1985

Microinjected ras family oncogenes stimulate DNA synthesis in quiescent mammalian cells.

Oncogenes of the ras family stimulate DNA synthesis when microinjected into quiescent mouse and hamster fibroblasts, as detected by in situ autoradiography. The molecularly cloned genomes of Harvey and Kirsten sarcoma viruses, the cloned Harvey ras gene, and the product of the v-ras gene, the p21v-rasH protein, stimulate DNA synthesis in quiescent cells. This stimulation is comparable to the stimulatory activity of the microinjected SV40 T-antigen-coding gene. The demonstration that these oncogenes can stimulate transient DNA synthesis in quiescent cells is relevant to understanding the mechanism by which these genes are able to transform cells in vitro and induce tumors in animals.

Animals↗

PubMed1976

Analgesia and hyperractivity following morphine microinjection into mouse brain.

Analgesia and a paradoxical hyperreactivity to stimuli of sudden onset have recently been reported following the microinjection of morphine into the periacqueductal gray matter of rats. These effects have not been systematically investigated in other species. In the present study, both analgesia and hyperreactivity were observed as dose dependent effects of morphine microinjection into the periacqueductal gray matter of several strains of mice. Analgesia alone was produced by low doses of morphine while at higher doses analgesia was accompanied by hyperreactivity. Strain differences were noted with B6D2F1 mice being more susceptible to the hyperreactivity following morphine than BALB/c mice.

Analgesia↗

PubMed1978

Mapping of early SV40-specific functions by microinjection of different early viral DNA fragments.

DNA sequences within the early simian virus 40 (SV40) genome region responsible for virus-specific tumor (T) and U antigenicity, stimulation of cell DNA synthesis, initiation of late SV40 gene expression and helper function for human adenovirus 2 were confined by experiments using microinjection of different early SV40 DNA fragments. All these early functions were detected in cells supplied with complete early viral information. Cells microinjected with DNA fragments containing about 80, 70 or 60% of thea early SV40 genome were still stained positively when challenged with antibody against T antigen, and the same cells were stimulated for cellular DNA synthesis when about 70% or more of the early viral information was available. DNA sequences at map position 0.67 are required for intracellular early viral transcription.

Antigens, Neoplasm↗

PubMed1990

Developmental potential of early bovine zygotes submitted to centrifugation and microinjection following in vitro maturation of oocytes.

This study was designed to investigate the potential use of in vitro matured, in vitro fertilized bovine zygotes for producing transgenic calves by microinjection of foreign DNA. In Experiment 1, the effect of centrifugation (4 min, 15,000 x g, 20 degrees C) on in vitro derived bovine zygotes was evaluated. In vitro development from 2 to 8 cells was not affected (80 vs 78%) when control zygotes (n = 211) were compared with zygotes treated (n = 210) 18 h post insemination. In Experiment 2, the influence of the centrifugation alone on the developmental potential of embryos was evaluated in rabbit oviducts for 120 h. The percentage of control and treated zygotes that developed to 1, 2 to 8, 8 to 32 and more than 32 cells were 7, 54, 10 and 10% vs 7, 40, 11 and 10%, respectively. In Experiment 3, the effect of pronuclear injection with plasmid containing CRF (corticotropin releasing factor) gene or pOCAT 330 Delta 1 plasmids; 2 microg/ml in Tris 10 mM, EDTA 0.2 mM, 18 to 20 h post insemination was evaluated by in vivo development in the rabbit oviduct. The embryos submitted only to centrifugation and vortexing resulted in a morula-blastocyst (> 32 cells) rate of 25% (n = 226) compared with the injected zygotes of which only 5% (n = 206) achieved the same stage. We conclude that in vitro produced bovine zygotes have a reduced developmental potential following microinjection, and this effect is not due to the centrifugation process.

Journal Article↗

PubMed1991

Gene transfer in common carp (Cyprinus carpio L.) by microinjection into the germinal disc.

We report here on the microinjection of the human growth hormone gene (hGH) into the germinal disc of common carp one-cell embryos. For microinjection, a linear 4.1 kb EcoRi-DNA fragment containing the mouse metallothionein-I promoter (mMT-I), fused to a structural gene coding for the hGH, was used. Of the 14 injected embryos, 9 developed to an age of 60 d. Of these nine fish, two were found to be transgenic and had integrated two to four copies per cell of the hGH construct.

Journal Article↗

PubMed1992

Evaluation of systems for collection of porcine zygotes for DNA microinjection and transfer.

Crossbred gilts and sows (n=116) were used for the collection of 1-cell zygotes for DNA microinjection and transfer. Retrospectively, estrus synchronization and superovulation schemes were evaluated to assess practicality for zygote collection. Four synchronization and superovulation procedures were used: 1) sows were observed for natural estrous behavior; 1000 IU human chorionic gonadotrophin (hCG) was administered at the onset of estrus (NAT); 2) cyclic gilts were synchronized with 17.6 mg altrenogest (ALT)/day for 15 to 19 days followed by superovulation with 1500 IU pregnant mares serum gonadotropin (PMSG) and 500 IU hCG (LALT); 3) gilts between 11 and 16 days of the estrous cycle received 17.6 mg ALT for 5 to 9 days and PMSG and hCG were used to induce superovulation (SALT); and 4) precocious ovulation was induced in prepubertal gilts with PMSG and hCG (PRE). A total of 505 DNA microinjected embryos transferred into 17 recipients produced 7 litters and 50 piglets, of which 8 were transgenic. The NAT sows had less (P < 0.05) ovarian activity than gilts synchronized and superovulated by all the other procedures. Synchronization treatments with PMSG did not differ (P > 0.05) in the number of corpora hemorrhagica or unovulated follicles, but SALT and PRE treaments had higher ovulation rates than LALT (24.7 +/- 2.9, 24.3 +/- 1.8 vs 11.6 +/- 2.7 ovulations; X +/- SEM). The SALT and PRE treatments yielded 12.3 +/- 2.6 and 17.7 +/- 1.7 zygotes. Successful transgenesis was accomplished with SALT and PRE procedures for estrus synchronization and superovulation.

Journal Article↗

PubMed1996

Effect of pronuclear DNA microinjection on the development of porcine ova in utero.

The objective of this study was to assess the effect of various aspects of pronuclear DNA microinjection on the early development of porcine ova in utero. Estrus was synchronized and superovulation was achieved in sexually mature gilts by the administration of allyl trenbolone, PMSG and hCG. Donor gilts were bred at 12 and 24 h after the onset of estrus. Ova were recovered between 60 and 62 h after the administration of hCG. One-cell ova that exhibited pronuclei after centrifugation were randomly allocated in equal numbers from each donor across one of two pairs of treatments: micro-DNA (ova were injected with two gene constructs that code for the human complement regulatory proteins decay accelerating factor and membrane cofactor protein) and control (ova were centrifuged only) or micro-buffer (ova were injected with buffer only) and pierced (a pipette was inserted into one pronucleus). Ova were transferred by treatment pairs to recipients. Treatments were segregated by oviduct. Ova were recovered after 120 h in utero, fixed and stained with 1% orcein. The proportion of ova that possessed > or = 80 nuclei, the mean number of nuclei present and proportion of ova that formed blastocysts were all significantly (P<0.05) greater for control and pierced ova than for micro-DNA and micro-buffer ova. No difference in these parameters was observed between micro-DNA and micro-buffer ova. These results demonstrate that pronuclear microinjection of a buffer alone can adversely affect the early development of porcine ova in utero.

Journal Article↗

PubMed1992

Defense reaction elicited by microinjection of kainic acid into the medial hypothalamus of the rat: antagonism by a GABAA receptor agonist.

Electrical stimulation of either the midbrain central gray or the medial hypothalamus induces a defense reaction in the rat, characterized mainly by increased locomotion, rearing, and leaping. However, microinjection of the excitatory amino acid glutamate was effective only in the former region. Because excitatory amino acids do not depolarize axons of passage, it was suggested that the hypothalamus is devoid of soma/dendrites of neurons commanding the defense reaction. In the present study, we show that a subtoxic dose (60 pmol) of another excitatory amino acid, kainic acid, injected into the medial hypothalamus significantly enhanced locomotion and rearing of Wistar rats systematically observed in an open field. Similar behavioral changes have been reported following microinjection of drugs impairing GABAergic neurotransmission. Local pretreatment with the GABAA receptor agonist THIP (2 nmol) blocked the effect of kainic acid. Therefore, the medial hypothalamus of the rat seems to contain a population of neuronal cell bodies commanding the defense reaction, which is activated by excitatory amino acids and tonically inhibited by GABAergic fibers.

Agonistic Behavior↗

PubMed1985

Differential effects of intrafrontocortical microinjections of dopamine agonists and antagonists on circling behavior of rats.

Asymmetric posturing and circling behavior resulting from acute unilateral manipulation of central dopamine have been used to assess this neurotransmitter's contribution to motor control. Although providing extensive evidence for the involvement of mesolimbic and nigrostriatal dopamine in motor activity, this approach has not been used to study the mesocortical system. We now report circling behaviour following acute manipulation of frontal cortical dopamine. Unilateral microinjections of the agonists, (+)-amphetamine (12 and 25 micrograms in 1.0 microliter) and LY 141865 (12 micrograms in 1.0 microliter) resulted in contraversive circling. Conversely, unilateral intrafrontocortical microinjections of the antagonist, metoclopramide (25 and 100 micrograms in 1.0 microliter) resulted in ipsiversive circling in amphetamine (1.5 mg/kg, i.p.) pretreated rats. Lower central doses of each drug and vehicle injections had no significant effect. These results provide evidence for an excitatory influence of mesocortical dopamine on motor control. This finding may implicate frontal cortical dopamine in the extrapyramidal motoric side effects of chronic neuroleptic treatment which previously have been attributed to dopamine function in subcortical areas.

Animals↗

PubMed1986

Flight induced by microinjection of D-tubocurarine or alpha-bungarotoxin into medial hypothalamus or periaqueductal gray matter: cholinergic or GABAergic mediation?

Microinjections of various doses (50-300 ng) of the nicotinic antagonist D-tubocurarine (TUBO) into the rat's medial hypothalamus (MH) or dorsal periaqueductal gray (PAG) produced flight reactions characterized by jumps. Two different types of flight reactions were produced depending on whether the drug was injected into the MH or into the PAG. MH injections provoked an increase in both locomotor activity and rearing together with well-oriented jumps. PAG injections provoked either freezing reactions or running with explosive jumps, but no increase in rearing. In addition, the rat exhibited an asymmetry in responsiveness to tactile stimulation. These reactions also differed depending on whether the drug was injected into the dorsal or ventral PAG. Behavioral reactions similar to those produced by TUBO were also produced by microinjection of the GABA receptor antagonist bicuculline into the same brain sites. Among the 4 putative cholinergic antagonists tested under the same conditions only alpha-bungarotoxin produced effects that were qualitatively similar to those induced by D-tubocurarine or bicuculline. Gallamine and hemicholinium produced tremor when injected into sites located near the ventricular system at either the MH or the PAG level, while vocalizations were only produced by PAG injections. Hexamethonium produced no marked effect. The hypothesis that flight reactions induced by D-tubocurarine or alpha-bungarotoxin do not result from their antinicotinic action but rather from a direct effect on GABAergic transmission is discussed.

Acetylcholine↗

PubMed1983

Low dose of morphine microinjected in the ventral periaqueductal gray matter of the rat depresses responses of nociceptive ventrobasal thalamic neurons.

The effect of low doses of morphine (2 micrograms in 0.2 microliter) microinjected in the periaqueductal gray matter (PAG) was studied on responses of 11 nociceptive (N) and 3 non-nociceptive (Nn) ventrobasal (VB) thalamic neurons in lightly anesthetized rats. Responses of Nn neurons were unmodified but their receptive field was consistently enlarged during 50-60 min. Responses of N neurons to calibrated pinches were strongly depressed when the microinjection site was located in the PAG or in the dorsal raphe (NDR) (7 cases), and not significantly changed when morphine was applied in the dorsal PAG. For the 7 depressed neurons, the mean value of the responses expressed as a percentage of the control was 20.12 +/- 5.17, 15 min after morphine application. This depressive effect was variably reversed by naloxone (0.1-0.5 mg/kg).

Animals↗

PubMed1983

Analgesia for orofacial nociception produced by morphine microinjection into the spinal trigeminal complex.

Morphine sulfate (0.75 micrograms) was microinjected into (rat) rostral and caudal trigeminal areas singly and simultaneously, using cannula-electrode combinations. Also, 0.5 micrograms or 1.0 micrograms of morphine was injected into nucleus reticularis paragigantocellularis (PGC). Both single trigeminal nuclear microinjections significantly elevated the latency to a defensive face-rub reaction to noxious facial heat, bilaterally. There was no summation effect with the conjoint injection of 1.5 micrograms total to rostral and caudal nuclear areas. The 0.5 micrograms injection in PGC had a significantly larger effect than did the 0.75 microgram trigeminal injections. The caudal but not the rostral trigeminal injections did elevate the threshold for aversive reaction to caudal trigeminal nuclear stimulation of the injected tissue. This finding contrasts with the previously reported fact that as much as 1.0 microgram of morphine in PGC has no effect on this aversive reaction threshold to brain stimulation.

Analgesia↗

PubMed1989

Differential actions of the blockade of spinal opioid, adrenergic and serotonergic receptors on the tail-flick inhibition induced by morphine microinjected into dorsal raphe and central gray in rats.

Microinjection of morphine sulfate into dorsal raphe, ventrolateral central gray and dorsolateral central gray inhibits spinal nociceptive reflexes. The effects of the blockade of spinal opioid, adrenergic, and serotonergic receptors by intrathecal injection of naloxone, yohimbine and methysergide, respectively, on inhibition of the tail-flick response induced by morphine microinjected into dorsal raphe, ventrolateral central gray and dorsolateral central gray were studied. Naloxone (20 micrograms) given intrathecally effectively antagonized inhibition of the tail-flick response induced by morphine (4 micrograms) given into dorsal raphe and ventrolateral central gray, but not dorsolateral central gray. On the other hand, intrathecal injection of yohimbine (30 micrograms) antagonized inhibition of the tail-flick response induced by morphine given into ventrolateral central gray and dorsolateral central gray, but not dorsal raphe. Intrathecal injection of prazosin (30 micrograms) did not antagonize inhibition of the tail-flick response induced by morphine given into dorsal raphe or lateral central gray. Intrathecal injection of methysergide (30 micrograms) only partially antagonized inhibition of the tail-flick response induced by morphine given into dorsal raphe, but not ventrolateral central gray and dorsolateral central gray. It is concluded that the analgesia induced by morphine injected into dorsal raphe is mediated by spinal opioid receptors but not by spinal alpha 2-adrenergic receptors while the analgesia produced by morphine given into dorsolateral central gray is mediated by spinal alpha 2-adrenergic receptors. The analgesia induced by morphine given into ventrolateral central gray is mediated in part by both spinal alpha 2-adrenergic and opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2005

Homeostatic alterations induced by interleukin-1beta microinjection into the orbitofrontal cortex in the rat.

The present experiments were designed to elucidate the effect of direct orbitofrontal cortical administration of interleukin-1beta (IL-1beta) on the homeostatic regulation. Short- and long-term food intakes (FI), water intakes and body temperature (BT) were measured before and after a bilateral microinjection of IL-1beta (with or without paracetamol /P/ pretreatment) into the orbitofrontal cortex (OBF) of Wistar rats, and the effects were compared with those found in vehicle-treated and i.p. injected IL-1beta, IL-1beta+P or control animals. In addition, blood glucose levels (BGLs), along a glucose tolerance test, and plasma concentrations of insulin, leptin, cholesterol, triglycerides and urate were determined in cytokine treated and control rats. Short-term FI was suppressed after orbitofrontal cortical or peripheral application of IL-1beta. In the long-term FI, however, there was no significant difference among the groups. Cytokine microinjection into the OBF, similar to the i.p. administration, was also followed by a significant increase in BT. Pretreatment with P failed to influence the anorexigenic and hyperthermic effects of the centrally administered IL-1beta. The sugar load led to a diabetes-like prolonged elevation of BGL in the IL-1beta treated animals. Following cytokine administration, plasma levels of insulin and that of triglycerides were found decreased, whereas that of uric acid increased. The present findings confirm that the OBF is one of the neural routes through which IL-1beta exerts modulatory effect on the central homeostatic regulation.

Animals↗