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At least 1,423 records · Page 79Linked to original sources
PubMed2001

Microinjection of antisense c-mos oligonucleotides prevents the progression of meiosis in human and hamster oocytes.

OBJECTIVE: To investigate the role of c-mos proto-oncogene in the progression of meiosis in human and hamster oocytes. DESIGN: Controlled basic research study. SETTING: Assisted reproduction units at medical institutions. PATIENT(S): Consenting in vitro fertilization patients. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Maturation to metaphase II (MII) 24 hours following microinjection of prophase I (PI) hamster oocytes with antisense (AS) and sense (S) c-mos oligonucleotides. Control oocytes (C) injected with medium or left uninjected (UI). In human oocytes, maturation to metaphase II was also measured except culture was extended to 48 hours and the sense group was omitted. RESULT(S): The percentage of hamster oocytes reaching metaphase II after 24 hours was as follows: 1.5% (1 of 65) for the antisense group; 63.1% (41 of 65) in the sense group; 66.1% (41 of 62) in the control group; and 69.3% (52 of 75) in the uninjected group. The percentage of human oocytes at metaphase II was 33.3% (4 of 12) in the antisense group, 83.3% (10 of 12) in the control group, and 82.8% (24 of 29) in the uninjected group. CONCLUSION(S): These results demonstrate that injection of c-mos antisense oligonucleotide significantly inhibits the progression of meiosis in hamster (P=.0001) and human (P=.05) oocytes. Thus, c-mos proto-oncogene may be one of the critical regulators of meiosis in these two species.

Animals↗
PubMed2002

Beneficial effect of microinjected trehalose on the cryosurvival of human oocytes.

OBJECTIVE: To determine the effectiveness of trehalose as an intracellular cryoprotectant for the cryopreservation of human oocytes. DESIGN: In vitro comparative study. SETTING: Clinical and academic research environment at a medical school teaching hospital. PATIENT(S): Women undergoing in vitro fertilization (IVF). INTERVENTION(S): Discarded human oocytes, obtained from IVF patients, were randomly distributed into three groups: control group (no trehalose), extracellular trehalose group (0.5 M extracellular trehalose), and intracellular trehalose group (0.15 M intra- and 0.5 M extracellular trehalose). Trehalose was introduced into oocytes by microinjection. The oocytes in each group were cooled to different temperatures (i.e., -15 degrees C, -30 degrees C, and -60 degrees C) at rate of 1 degrees C/minute and thawed at ambient air temperature. Survival was examined after overnight culture. MAIN OUTCOME MEASURE(S): Survival of human oocytes cryopreserved in the presence and absence of trehalose. RESULT(S): The majority of oocytes in the intracellular trehalose group survived cooling to -15 degrees C (63%), -30 degrees C (53%), and -60 degrees C (66%). In contrast, only a small number of oocytes in both the control (13%) and extracellular trehalose group (22%) survived cooling to -15 degrees C, while all oocytes degenerated when cooled to -30 degrees C and -60 degrees C. CONCLUSION(S): Small amounts of intracellular trehalose in the absence of any other cryoprotectant provide a significant protection against freeze-associated stresses. Our results suggest that sugars such as trehalose should be considered as intracellular cryoprotectants for cryopreservation of human oocytes.

Cell Survival↗
PubMed1991

Microinjection of human oocytes: a technique for severe oligoasthenoteratozoospermia.

OBJECTIVE: To determine outcome after microinjection with very poor quality sperm and after failed fertilization. DESIGN: Group 1, fresh oocytes from patients with very low sperm density and motility on the day of oocyte recovery; Group 2, 1-day-old oocytes that failed to fertilize. SETTING: All material was obtained from the National University Hospital. PATIENTS: One hundred and thirty-one from group 1; 35 from group 2. INTERVENTIONS: Sperm was injected subzonally or directly into the ooplasm. MAIN OUTCOME MEASURE: Normal and abnormal fertilization and pregnancy. RESULTS: Subzonal transfer was done on 771 oocytes in group 1 and 188 oocytes in group 2. Multiple sperm were transferred [mean of 6.6 for group 1 and 7.3 for group 2]. Monospermic fertilization occurred in 16.6% and 14.9%, respectively. Polyspermy and parthenogenetic activation were low at 2.3% and 2.8%, respectively. Five pregnancies were obtained, but only one delivered. Ooplasmic injection (single sperm heads) was done in 38 oocytes from three patients with extremely severe oligozoospermia; only four two-pronuclear zygotes were obtained and replaced into two patients, without any resulting pregnancy. CONCLUSIONS: Subzonal transfer may be a viable technique for patients with severe sperm problems.

Female↗
PubMed1997

Testicular and epididymal sperm in a microinjection program: methods of retrieval and results.

OBJECTIVE: To describe the methods of collection and laboratory preparation of epididymal and testicular sperm; to compare the fertilization and pregnancy rates; and to establish prognostic factors. DESIGN: Retrospective analysis. SETTING: Academic reproductive medicine clinic. PATIENT(S): One hundred twelve consecutive microinjection cycles in 80 patients using either epididymal or testicular sperm. INTERVENTION(S): Sperm were collected by microepididymal sperm aspiration, open testicular biopsy, or fine needle tissue aspiration testicular biopsy. MAIN OUTCOME MEASURE(S): Fertilization rate, implantation, and clinical pregnancy rates. RESULT(S): The fertilization rate was higher with epididymal sperm (67%) than with testicular sperm (50%). Implantation rates (fetal hearts per embryo, testicular: 11%, epididymal: 8%) and pregnancy rates (clinical pregnancy per oocyte collection procedure, testicular: 25%, epididymal: 29%) were not significantly different with epididymal and testicular sperm. Multiple regression analysis showed that normal fertilization rates were significantly lower with testicular sperm, immotile sperm, and severe spermatogenic disorders. CONCLUSION(S): Although fertilization rates are significantly lower with testicular sperm, higher implantation rates resulted in equivalent pregnancy rates. Thus, testicular aspiration of sperm for intracytoplasmic sperm injection is a simple, inexpensive method of sperm retrieval in cases of azoospermia resulting from genital tract obstruction or severe spermatogenic disorder.

Biopsy↗
PubMed1998

The spatial organisation of the central nervous system of Mesocestoides corti as revealed by microinjection of carbocyanine dye.

The carbocyanine dyes DiI, DiA and DiO were microinjected into the cerebral ganglion of intact Mesocestoides corti tetrathyridia to determine the spatial organisation and connectivity patterns of the CNS. Of the dyes tested, DiI proved to be the most effective, giving highly fluorescent and persistent staining of even very fine calibre afferent and efferent nerve fibres. DiI labelling, in conjunction with transmission electron microscopy, revealed the nervous system to consist of sensory endings, directly connected to the cerebral ganglion by elongated cellular tracts, efferent nerve fibres which innervated the suckers, and longitudinal nerve cords which travelled along the remainder of the body.

Animals↗
PubMed2003

Acute intracerebroventricular insulin microinjection after nitric oxide synthase inhibition of renal sodium handling in rats.

The role of the central nervous system (CNS) in the control of hydrosaline homeostasis has been strikingly demonstrated by several studies. Recent and growing evidence suggests that insulin or a nonapeptide-derived from the C-terminus of the insulin beta-chain may influence many brain functions. However, there is little information on the insulin-activated neural pathways regulating urinary sodium excretion. Also, we examined the influence of nitric oxide synthase activity by chronic oral administration of N(omega)-nitro-l-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, after previous i.c.v. administration of insulin to unanesthetized, unrestrained rats that were randomly assigned to one of seven separated groups: (a) i.c.v. 0.15 M NaCl-injected (n = 11) and i.c.v. 126 ng (n = 11) insulin-injected rats; (b) i.c.v. insulin-injected in systemic L-NAME-treated (n = 10) and vehicle-treated insulin-injected rats (n = 10); and (c) subcutaneously (SC) insulin-injected rats (n = 5). We showed that centrally administered insulin produced increase in the urinary output of sodium (from 0.15 M NaCl: 855.6 +/- 85.1 Delta%.min(-1) to 126 ng insulin: 2055 +/- 310.6 Delta%.min(-1)) and potassium (126 ng: from 0.15 M NaCl: 460.4 +/- 100 Delta%.min(-1) to 126 ng insulin: 669 +/- 60.8 Delta%.min(-1)). The urinary sodium excretion response to i.c.v. 126 ng insulin microinjection was significantly abolished by previous systemic treatment of animals with 15 mg/kg/day L-NAME (from vehicle + 126 ng insulin: 1935 +/- 258.3 Delta%. min(-1) to L-NAME + 126 ng insulin: 582.3 +/- 69.6 Delta%. min(-1)). In addition, we showed that insulin-induced natriuresis occurred by increasing post-proximal tubule sodium rejection (FEPP(Na)), despite an unchanged glomerular filtration rate (C(Cr)). The current data suggests the novel concept that CNS NO-dependent neural pathways may play an instrumental role on efferent insulin-sensitive nerve activity from periventricular region. Speculatively, it seems interesting to suggest that perhaps one of the efferent signals triggered by insulin in the CNS may be nitrergic in nature, and that defects in this efferent signal could result in insulin central resistance, inability of renal tubules to handle the hydro electrolyte balance and hypertension.

Animals↗
PubMed1999

Effects of microinjections of triazolam into the ventrolateral preoptic area on sleep in the rat.

In view of interest in the ventrolateral preoptic area (VLPO), based on FOS protein accumulation during sleep as well as its output pathways to areas involved in sleep regulation, we have examined the effects of microinjections of triazolam into the VLPO. It was found that two doses of triazolam, noted previously to enhance sleep when injected into the medial preoptic area, had no significant effect on sleep or core temperature when administered into the VLPO. Although these data do not bear on the possibility that the VLPO is involved in physiological sleep regulation, they suggest that it is not a site of the pharmacologic action of hypnotic benzodiazepines.

Animals↗
PubMed2003

Dopaminergic involvement in medial prefrontal cortex and core of the nucleus accumbens in the regulation of ethanol self-administration: a dual-site microinjection study in the rat.

The complex mesolimbic-mesocortical system involved with behavioral selection has been implicated in the control of ethanol self-administration. However, the nature of the interactions within this multiple-structured system in ethanol intake regulation remains unclear. Although the role of dopamine (DA) in the prefrontal cortex and the nucleus accumbens has been examined individually, the interaction of DA activity in both structures at the same time remains to be examined. Male, Long-Evans rats were initiated to self-administer ethanol in an operant situation using the sucrose-substitution procedure. Following initiation, bilateral cannula guides were located to allow microinjection in the medial prefrontal cortex (mPFC) and the core of the nucleus accumbens. The DA D2/D3 agonist quinpirole (10.0-microg dose in the prefrontal cortex; 4.0-microg dose in n. accumbens) and the D2 antagonist raclopride (0.05-microg dose in prefrontal cortex; 1.0-microg dose in the nucleus accumbens) were then tested in each site alone and in combination in both sites in each rat. Changes in total responding, ethanol intake, and the pattern of responding were analyzed. Single-site injections replicated most of our previous findings for these doses. Changes in single-site effects were found when dual-site injections were performed, with altered input from the prefrontal areas impacting the effects of accumbens injections. Based on these interactions, our hypothesis that the prefrontal area is involved with the onset and offset of drinking, while the nucleus accumbens is involved with maintaining the ongoing behavior, remains viable.

Alcohol Drinking↗
PubMed1997

Naloxone microinjected into the arcuate nucleus has differential effects on ventilation in male and female rats.

The arcuate nucleus of the hypothalamus, a highly sexually dimorphic brain region, has been called the bed nucleus for endogenous opioids. The potential contribution of opioids in this nucleus to modulate control of ventilation in male and female rats has not been investigated. The purpose of the present study is to determine the effect of microinjecting naloxone, an opioid receptor antagonist, into the arcuate nucleus of awake male and female rats on ventilation, oxygen consumption, heart rate, and blood pressure. Results of this study demonstrate that naloxone at doses of 1.5 and 3.0 nmol relative to vehicle caused a depression of ventilation due to a decrease of both frequency of breathing and tidal volume in male rats and a decreased response to a hypercapnic challenge in female rats. Although there were gender differences noted in oxygen consumption, heart rate, blood pressure, and ventilatory response to a hypoxic challenge, only oxygen consumption was significantly affected by naloxone. Potential mechanisms whereby naloxone may act to depressing ventilation are discussed.

Animals↗
PubMed1997

Cardiorespiratory effects of L-glutamate microinjected into the rat ventral medulla.

We investigated the cardiorespiratory effects elicited by microinjections of L-glutamate (L-glu, 25 nmol, 200 nl) at various sites in the ventral medulla (VMS) of urethane-anesthetized rats. The results demonstrated that regions responsive to the drug are located along a column in the VMS extending from the VI cranial nerve to the first cervical nerve in the caudal medulla. Within this column three breathing patterns were elicited from four distinct areas. In the most rostral and caudal portion of this hypothetical column, the breathing patterns observed in response to L-glu were similar and characterized by increases in minute ventilation, tidal volume, inspiratory drive, respiratory frequency, mean arterial blood pressure (MAP) and heart rate (HR). In the regions located between the areas described above two different breathing patterns were obtained without significant changes in MAP or HR. These patterns were characterized by decreases and increases in the respiratory indices analyzed, with the exception of respiratory frequency, which decreased in both regions. These results suggest that within the VMS discrete areas may act as functional units modulating cardiorespiratory responses while in others these functions are spatially segregated.

Animals↗
PubMed2005

In situ measurements of metabolite fluxes: microinjection of radiotracers into insect guts and other small compartments.

In microbial ecology, it is of great interest to determine metabolic activities under in situ conditions, i.e., without disturbing the structure of the community and the spatial arrangement of individual populations by experimental manipulation. Microinjection of radiotracers and subsequent analysis using the isotope dilution technique has proven to be a powerful method to measure metabolic fluxes in small biological systems, e.g., the intestinal tract of termites. The large variety of commercially available radiolabeled substrates and the identification and quantitation of radiolabeled products by chromatographic methods allow for investigation of the complete metabolic network in a given system.

Animals↗
PubMed2000

Food intake after diazepam, morphine or muscimol: microinjections In the nucleus accumbens shell.

This study examined the effect on food intake of bilateral microinfusions of the benzodiazepine agents, diazepam and midazolam, the opioid agonist, morphine, and the GABA(A) agonist, muscimol into the shell of the nucleus accumbens in rats. Both muscimol (at 0.075 microg, combined bilateral dose) and morphine (1.0 microg) in the nucleus accumbens shell increased feeding as expected. However, it was clear that diazepam (2.5, 5.0, 25, 50 microg) and midazolam (7.5 microg) both failed to enhance feeding even at doses that are effective when microinjected in the brain stem. We conclude that opioid and GABA(A) agents promote feeding behavior by acting on receptors in the nucleus accumbens shell, but that benzodiazepines probably act elsewhere in the brain to increase food intake.

Animals↗
PubMed2001

Estrus variation in anticonflict effects of midazolam microinjected into septal nuclei in female Wistar rats.

Effects of midazolam intraperitoneally (3.0 mg/kg) administered, or locally applied into lateral septal nuclei (10 microg/microl), or into the medial septum (10 microg/microl) were assessed in Wistar rats during late proestrus or metestrus-diestrus in a conflict-operant task. A reduction in conflict behavior was found in control rats during late proestrus (P<.05), when compared to metestrus-diestrus. Systemic injections of midazolam (P<.05) or midazolam infusions into lateral septal nuclei (P<.05) also reduced conflict behavior only during late proestrus, whereas midazolam infusions into the medial septum produced neither of these anticonflict effects in any estrous phase. In conclusion, an endocrine-related variation in anticonflict effects of midazolam microinjected into lateral septal nuclei was displayed by female rats.

Animals↗
PubMed1984

Rotation and postural deviation elicited by microinjections of dopamine into medial and lateral regions of dorsal striatum.

Unilateral microinjections of DA (25 micrograms/0.25 microliter) into several medial to lateral regions of the dorsal striatum of female rats produced both contralateral postural deviation and rotation. However, injections of DA into the medial striatum were more effective in producing rotation than postural deviation, whereas the opposite was the case for lateral striatal injections.

Animals↗
PubMed1997

Role of dopamine in behavioral effects of serotonin microinjected into rat striatum.

Bilateral local microinfusion of serotonin (5-hydroxytryptamine; 5-HT) into the ventrolateral striatum (VLS) of the rat forebrain induces quantifiable stereotyped orofacial behaviors. The role of presynaptic dopamine (DA) and structural requirements of indoles for expression of this behavioral effect and for inhibition of neuronal transport of [3H]DA were examined. Bilateral local injection of 6-OHDA (8 micrograms/side) into VLS depleted DA and markedly diminished the behavioral effects of 5-HT. Intracerebral pretreatment with the potent DA transport inhibitors GBR-12909 (6 micrograms/side) or nomifensine (4 micrograms/side) also markedly decreased behavioral responses to 5-HT. A series of indoles and tyramine were examined for ability to induce stereotypy following infusion into the VLS. Of compounds tested, only p-tyramine, 5-HT, tryptamine and L-5-hydroxytryptophan (5-HTP) elicited strong orofacial behaviors; indoles lacking a free amino group or containing other substituents were virtually inactive in vivo, and the effect of 5-HTP was prevented by systemic pretreatment with the decarboxylase inhibitor NSD-1015, indicating its required conversion to 5-HT. Uptake of [3H]DA (0.1 microM) into rat striatal synaptosomes was inhibited in a concentration-dependent manner in the following apparent rank-order: p-tyramine, N-methyl-5-HT, tryptamine, 5-HT, N-methyltryptamine (IC50 = 44-718 nM), other indoles (IC50 = 10-100 microM). These results support the conclusion that oral stereotypy induced by microinjection of 5-HT or other aromatic amines into rat VLS is mediated by local release of endogenous DA. These results extend previous findings indicating that this effect of 5-HT was not blocked by 5-HT receptor antagonists, and suggest mediation by a neuronal transport process involved in the uptake or storage of DA.

Animals↗
PubMed1997

Effects of microinjections of cholecystokinin and neurotensin into lateral hypothalamus and ventral mesencephalon on intracranial self-stimulation.

Changes in intracranial self-stimulation (ICSS) evoked from ventral tegmental area-substantia nigra (VTA-SN) and lateral hypothalamus-medial forebrain bundle (LH-MFB) before and after microinjections of sulfated cholecystokinin octapeptide (CCK-8S) and unsulfated cholecystokinin (CCK-8US), neurotensin tridecapeptide ([D-Tyr11]NT(1-13) or [DTrp11]NT(1-13)) into either VTA-SN or LH-MFB were assessed. The current intensity was fixed at a level to obtain 60-70% of the maximal asymptotic rate. CCK-8S (0.10 microg/0.5 microl and 0.25 microg/0.5 microl) into VTA-SN resulted in dose-dependent decreases in VTA-SN ICSS of 38-42% and 78-92%, respectively, without affecting the ICSS of LH-MFB. Similar doses of CCK-8S injected into LH-MFB changed neither LH-MFB ICSS nor VTA-SN ICSS. CCK-8Us injected into VTA-SN or LH-MFB had no effect on ICSS in either site. Intra-VTA-SN injections of the neurotensin-1 (NT1) receptor agonist [DTyr11]NT(1-13) and the NT1 receptor antagonist [D-Trp11]NT(1-13) at doses of 5 microg/0.5 microl and 10 microg/0.5 microl decreased VTA-SN ICSS. NT1 receptor agonist and antagonist injections did not alter LH-MFB ICSS in any significant manner. Similar injections of these peptides into LH-MFB did not change the responding rates for LH-MFB ICSS or VTA-SN ICSS. Increasing the current intensity reversed the inhibitory effect of CCK-8S and [D-Trp11]NT(1-13) on VTA-SN ICSS and restored basal preinjection rates of responding. These results suggest that CCK(A) and NT1 receptor mechanisms in the ventral tegmentum in association with dopamine neurotransmission may be important in mediating the rewarding effects of VTA-SN ICSS but not LH-MFB ICSS.

Animals↗
PubMed1998

Effects of intraaccumbens microinjections of quinopirole on head turning and circling movement in the rat.

This study was designed to evaluate whether nucleus accumbens dopamine D2 receptors are involved in the initiation of the movement, as distinguished from its execution. For this purpose, the effects of the quinpirole-induced increase of nucleus accumbens dopamine D2 receptor activity were observed on specific parameters of the circling behavior and of its first stage, the head-turning (HT) movement. The experiments were performed on rats with unilateral 6-hydroxydopamine (6-OHDA) lesion of the pars compacta of the substantia nigra and d-amphetamine i.p. (3 mg/kg). Bilateral intraaccumbens microinjections of quinpirole (1, 5, and 10 microg/0.5 microl), an agonist of the D2 receptor family, were performed on three groups of animals. Bilateral saline (0.5 microl) was injected in a fourth group as control. An additional control experiment, with quinpirole (10 microg/0.5 microl) bilaterally injected in accumbens without d-amphetamine i.p., was also performed in a further group of 6-OHDA-lesioned animals. By means of a videoanalysis system, HT duration, angle, and speed were analyzed. Modifications of the circling rate (increase), HT duration (decrease), HT angle (decrease or increase according to the dose), and HT speed (increase) were observed. Moreover, a very close head-to-tail position and a very short-diameter type of turn were also evidenced. Similar modifications, even if different in amplitude and in % distribution, were observed following bilateral quinpirole in accumbens without d-amphetamine i.p. The results indicate a close relationship among head-turning speed, type of turn, and position of the animal in the circling motor sequence. We conclude that D2 receptor family in nucleus accumbens is involved in the initiation of movement as distinguished from its execution.

Animals↗