Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Injectables”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,405 records · Page 78Linked to original sources
PubMed2002

Flow properties of liquid calcium alginate polymer injected through medical microcatheters for endovascular embolization.

The flow properties of liquid calcium alginate injections were investigated for application in endovascular embolization. Alginate shear properties were assessed with a rheometer and a controlled injection system. The experimental results were used to model the flow properties and predict alginate's flow characteristics within various medical microcatheter delivery systems. The results suggest that alginates undergo shear-thinning effects with increasing shear. A flow comparison of 2.0 wt % alginate and a Newtonian fluid (82 cP) injected from the same microcatheter had similar flow rates at low injection pressure (100 kPa). However, at high injection pressure (2100 kPa), the alginate was injectable at a flow rate 100% higher than was the Newtonian fluid. Further analysis of injections through microcatheters resulted in a flow model for predicting viscosity changes, flow rates, and injection pressures of liquid alginate at medium-to-high shear rates. The predicted injection pressures and flow rates had an average variance of less than 15% from that of the experimental flow data. This study indicates that calcium alginate has the requisite flow properties for successful delivery to vascular lesions via endovascular injection. Possible uses of alginates include treating arteriovenous malformations (AVMs), aneurysms, blood flow to tumors, and vascular hemorrhages.

Alginates↗
PubMed2005

Poly(lactic-co-glycolic acid) microspheres as a potential bulking agent for urological injection therapy: preliminary results.

Injection of bulking substances has been introduced as a new therapy to treat urinary incontinence and vesicoureteral reflux. Currently available bulking substances for the injection therapies include liquid or particulated silicone, collagen gel, and polytetrafluoroethylene paste. However, these materials have shown shortcomings such as inflammation, rapid volume decrease, and particle migration to distant organs. In the present study, we evaluated poly(lactic-co-glycolic acid) (PLGA) microspheres as a potential injectable bulking agent for the injection therapies. PLGA microspheres (52 microm in average diameter) were injectable through various gauges of needles, as the injected microspheres showed no tendency to obstruct the needles and microsphere size exclusion was not observed upon injection through the needles. After injection of PLGA microspheres into the subcutaneous dorsum of mice, inflammation, new tissue volume change, and microsphere migration were examined. Host cells from the surrounding tissues migrated to the implanted microspheres and formed new hybrid tissue structures. The volume of the newly generated tissues was maintained approximately constant for 7 weeks. Histological analyses showed no evidence of migration of the implanted microspheres to the distant organs. In summary, PLGA microspheres were injectable and able to induce a new hybrid tissue formation without initial volume decrease or particle migration. These preliminary results suggest that this material may be a potentially useful bulking agent for urological injection therapies.

Animals↗
PubMed1983

Subcutaneous administration of inactivated hepatitis B vaccine by automatic jet injection.

To assess the feasibility of jet injection for mass immunization against hepatitis B virus, inactivated, alum-adsorbed hepatitis B vaccine (Merck, Sharp, and Dohme Research Laboratories, West Point, PA) was administered subcutaneously by automatic jet injection to 19 volunteers lacking antibody to hepatitis B surface antigen (anti-HBs). Three 20-microgram doses were given at 0, 1, and 6 months. Of 19 volunteers, 5 (26%) developed anti-HBs by 1 month after the first injection, and 15 of 19 (79%) were anti-HBs-positive 6 to 8 weeks after the first booster administration. Following the second booster, 16 of 19 (84%) recipients had detectable anti-HBs. Possible systemic reactions were limited to low-grade fever (37.8 degrees C) in one volunteer following one injection, and mild lethargy in a second recipient. Local reactions to jet injection of vaccine occurred more frequently, with indurated, nodular lesions 3-10 mm in diameter developing at the site of 19 of 57 (33%) vaccine injections, compared with 2 of 57 (3%) saline placebo injections. Such nodules were generally painless. Sore arms were noted in 11 of 57 (19%) vaccine injections. With the exception of frequent but minor local reactions, subcutaneous administration of inactivated hepatitis B vaccine by automatic jet injection is safe, and results in vaccine immunogenicity approximating that associated with intramuscular needle injection.

Adult↗
PubMed2004

Avidin/biotin-liposome system injected in the pleural space for drug delivery to mediastinal lymph nodes.

The objective of this study was to develop a more effective liposome-based method for delivering drugs to mediastinal nodes. Nodal uptake was determined after intrapleural injection of the avidin/biotin-liposome system in normal rats. The effect of injection sequence (avidin injected 2 h before biotin-liposomes and vice versa), volume injected, and administered dose of the agents is described. Pharmacokinetics of the avidin/biotin-liposome system was monitored with scintigraphic imaging by labeling the biotin-liposomes with technetium-99m ((99m)Tc). To identify the nodes during the biodistribution studies, patent blue dye was encapsulated in the biotin-liposomes. Tissue biodistribution studies were performed 22 h after injection of the (99m)Tc-blue-biotin-liposomes. When avidin was injected before (99m)Tc-blue-biotin-liposomes, better mediastinal node targeting (15.7%; p < 0.05) was achieved than when biotin-liposomes were injected first (8.3%) or when only biotin-liposomes were injected (1.0%). Injection of a small dose of liposomes (0.5 mg phospholipid) and avidin (0.5 mg) resulted in the most favorable drug delivery to mediastinal nodes and other organs. Intrapleural injection of the avidin/biotin-liposome system could potentially be used for drug delivery to disease processes such as lung cancer, anthrax, and tuberculosis that invade mediastinal nodes and use them as centers of incubation and dissemination.

Animals↗
PubMed1993

Susceptibility changes following bolus injections.

The general mechanism of bulk magnetic susceptibility (BMS) induced MRI contrast following a bolus injection is elaborated. Combining radiolabeled tracer data for the first pass of a bolus injection through the human brain with the application of Wiedemann's law allows us to calculate the lower limit for the time course of the vascular BMS following the injection of any contrast agent. Superparamagnetic iron oxide particles produce a much larger effect than any mononuclear Ln(III) chelate. We also calculate the BMS changes occurring after a dilution bolus injection (of isosmolal physiological saline) subsequent to a prior slow infusion of an intravascular contrast agent. This technique bears some resemblance to the increasingly important approach that exploits changes in only the level of blood oxygenation. The calculation indicates that contrast changes after the dilution bolus injection are smaller than those following Ln(III) agent injections but larger than those due to changes in blood oxygenation and suggests a way to possibly enhance the latter. We present an in vivo study demonstrating the dilution bolus injection technique in the mouse brain, and that features its rapid repeatability. Extrapolation of these results to the human, however, indicates that the saline volumes required for venous injections, except possibly for cardiac studies, would be prohibitively large. Smaller, catheter-delivered arterial bolus injections are feasible. We also suggest a method for using an agent bolus injection to measure the parenchymal BMS, and thus the iron content, of pathologically iron-loaded tissue.

Algorithms↗
PubMed1997

Age-dependent differences in survival of striatal somatostatin-NPY-NADPH-diaphorase-containing interneurons versus striatal projection neurons after intrastriatal injection of quinolinic acid in rats.

Some authors have reported greater sparing of neurons containing somatostatin (SS)-neuropeptide Y (NPY)-NADPH-diaphorase (NADPHd) than projection neurons after intrastriatal injection of quinolinic acid (QA), an excitotoxin acting at NMDA receptors. Such findings have been used to support the NMDA receptor excitotoxin hypothesis of Huntington's disease (HD) and to claim that intrastriatal QA produces an animal model of HD. Other studies have, however, reported that SS/NPY/NADPHd interneurons are highly vulnerable to QA. We examined the influence of animal age (young versus mature), QA concentration (225 mM versus 50 mM), and injection speed (3 min versus 15 min) on the relative SS/NPY/NADPHd neuron survival in eight groups of rats that varied along these parameters to determine the basis of such prior discrepancies. Two weeks after QA injection, we analyzed the relative survival of neurons labeled by NADPHd histochemistry, SS/NPY immunohistochemistry, or cresyl violet staining (which stains all striatal neurons, the majority of which are projection neurons) in the so-called lesion transition zone (i.e., the zone of 40-60% neuronal survival). We found that age, and to a lesser extent injection speed, had a significant effect on relative SS/NPY/NADPHd interneuron survival. The NADPHd- and SS/NPY-labeled neurons typically survived better than projection neurons in young rats and more poorly in mature rats. This trend was greatly accentuated with fast QA injection. Age-related differences may be attributable to declines in projection neuron sensitivity to QA with age. Since rapid QA injections result in excitotoxin efflux, we interpret the effect of injection speed to suggest that brief exposure to a large dose of QA (with fast injection) may better accentuate the differential vulnerabilities of NADPHd/SS/NPY interneurons and projection neurons than does exposure to the same total amount of QA delivered more gradually (slow injection). These findings reconcile the discordant results found by previous authors and suggest that QA injected into rat striatum does reproduce the neurochemical traits of HD under some circumstances. These findings are consistent with a role of excitotoxicity in HD pathogenesis, and they also have implications for the basis of the more pernicious nature of striatal neuron loss in juvenile onset HD.

Aging↗
PubMed1989

Toxicity of IL-2 and Corynebacterium parvum following direct intracranial injection.

The toxicity of IL-2 and/or C. Parvum when injected directly into the mouse brain was examined by survival and histopathology using different numbers of injections, different doses of IL-2, different solvents for the IL-2, and different doses and routes of administration of C. Parvum. Two injections was found significantly to increase mortality (19%) over a single injection (4%). Mortality from two injections of 30,000 U (23%) or 60,000 U (20%) was higher than from two injections of 15,000 U (12%). The mortality from two injections with normal saline as solvent was much higher (29%) than from two injections with sterile water (19%) or D5W (9%). Two injections of IL-2 given simultaneously with C. Parvum showed a much higher mortality (26%) than other doses and routes of C. Parvum administration. Mice dying acutely (6-24 days) of toxicity showed an extensive mononuclear infiltrate at the site of injection. The brains of surviving mice (sacrificed at 30 days) showed a mild residual mononuclear cell infiltrate with the exception of mice which had received IL-2 and C. Parvum simultaneously. Brains from this latter group had an extensive residual mononuclear cell infiltrate.

Animals↗
PubMed1994

The pharmacokinetics of recombinant human erythropoietin after subcutaneous injection at different sites.

The pharmacokinetics of recombinant human erythropoietin (RhEPO) were investigated after subcutaneous (s.c.) injection in the thigh and in the abdominal wall. Eleven healthy subjects, age 24.4 years (median), were studied. Each subject received two s.c. injections of 100 U.kg-1 RhEPO dissolved in 1 ml water: one injection in the thigh and another in the abdomen. Serum erythropoietin was measured regularly by radioimmunoassay until 144 h after each injection. The mean residence time was significantly longer after injection in the thigh than in the abdomen (32.7 vs 26.2 h). The estimated half-life of absorption was significantly longer after injection in the thigh than after abdominal application (14.9 vs 12.3 h). The estimated half-life of elimination was not significantly different (4.4 vs 4.8 h). The relative difference in the area under the curve between injection in the abdomen and the thigh in the same subject ranged from -36% to +68% but there was no significant difference in bioavailability. The peak concentration was not significantly different and appeared at around 10 h (Cmax thigh, 175 U.l-1 vs Cmax abdomen, 216 U.l-1). A twin-peak configuration of the concentration vs time curve with a significant second peak at 24 h was found after injection in the thigh but not after abdominal injection. In conclusion, the mean residence time was longer after administration in the thigh, probably due to delayed absorption, but bioavailability was not significantly different. Following injection in the thigh the concentration curve had two peaks. The differences may be due to regional variations in lymph flow and to physical activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1991

Response of body temperature and serum iron concentration to repeated pyrogen injection in rabbits.

We measured body temperature and serum iron concentration after five daily consecutive injections of febrile doses of Salmonella typhosa lipopolysaccharide (0.1 micrograms/kg) and two doses of Staphylococcus aureus cell walls (1 x 10(7) and 5 x 10(7) cells) in rabbits. Tolerance to endotoxin injection, as manifest by a significant attenuation in the body temperature elevation, developed after the first injection of endotoxin. The endotoxin-induced fall in serum iron concentration was attenuated significantly by the 5th day of endotoxin injection. In contrast, no tolerance developed in either the body temperature or serum iron response following repeated daily injections of S. aureus. Rabbits rendered tolerant to endotoxin showed normal febrile and serum iron responses to subsequent S. aureus injection. Rabbits given serial injections of S. aureus, although not tolerant to S. aureus itself, exhibited attenuated body temperature responses but not serum iron responses to endotoxin injection. We suggest that repeated injection of endotoxin diminishes the ability of endotoxin to stimulate endogenous pyrogen (EP) synthesis and/or release, a property not shared by the gram-positive pyrogen S. aureus. However, repeated injection of S. aureus weakens the central endotoxin-EP pathway.

Animals↗
PubMed1981

Self-injection of barbiturates and benzodiazepines in baboons.

Self-injection of three barbiturates, six benzodiazepines, and chlorpromazine was examined in baboons. Intravenous injections of drug were dependent upon completion of 160 lever presses (a 160-response fixed-ratio schedule). A 3-h time-out period followed each injection, permitting a maximum of eight injections per day. Prior to testing each dose of drug, self-injection performance was established with cocaine. Subsequently, a test dose was substituted for cocaine. Amobarbital, pentobarbital, and secobarbital maintained the highest levels of self-injection, which were similar to those maintained by cocaine. Clonazepam, clorazepate, diazepam, flurazepam, medazepam, and midazolam maintained relatively modest levels of self-injection, while chlorpromazine maintained only low levels, which were in the range of vehicle control. Of the six benzodiazepines, midazolam produced the highest levels of self-injection. At the highest self-injected doses, the barbiturates produced anesthesia in contrast to the benzodiazepines, which produced only sedation. None of the drugs affected food intake except for chlorpromazine, which produced dose-related decreases. The differences among the drug classes (i.e., barbiturate, benzodiazepine, phenothiazine) with respect to the maintenance of self-injection correspond well with the results of previous animal and human drug self-administration studies.

Animals↗
PubMed1992

Left ventricular opacification after peripheral venous injection of a modified albumin solution.

The usefulness of a modified albumin solution was assessed in 8 dogs after peripheral venous and inferior vena cava injections. The contrast agent is a mixed solution made of glucose, albumin and glycerin, with sonicated microbubble diameter of 5.0 +/- 2.3 microns. Multiple injections (8 ml each) of this contrast agent (total 80 injections) into peripheral vein and inferior cava were performed. The blood pressure from femoral artery was measured before, during and after injections. Two-dimensional echocardiograms were recorded in a modified long axis view on videotapes for play back analysis. The pulmonary transit time and left ventricular contrast persistent time was determined for each injection. The videodensity of the region of interest (ROI) at the center of right ventricle and left ventricle was measured. The background videodensity of both ventricles was evaluated. The videodensity over the ROI of both ventricles with peak contrast enhancement was measured in all frames for 3 consecutive cardiac cycles. The peak videodensity of right and left ventricle subtracting the background videodensity of each ventricles was further calculated respectively. The injections caused no change in blood pressure or heart rate. All injections produced right ventricular contrast echo. As much as 85% of peripheral venous and 82.5% of inferior vena cava injections resulted in left ventricular contrast which was 0.68 and 0.65 as bright as that produced in the right ventricle. Pulmonary transit time and left ventricle contrast persistent time of peripheral venous injection was 4.05 +/- 0.53 and 13.67 +/- 4.28 seconds respectively. No difference of these data (3.93 +/- 0.47 and 11.65 +/- 4.66 seconds) from those produced by inferior vena cava injections were noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1981

Hemodynamic effects of rapid injection into the canine superior mesenteric artery.

We explored the hemodynamic effects of rapid injection of 0.9% saline and arterial blood into the canine superior mesenteric artery in anesthetized animals. Mesenteric artery blood flow and pressure were measured in the vessel distal to the site of injection. Injection rates were at or below the rate of blood flow in the mesenteric artery. Rapid injection of saline caused increases in blood flow and decreases in pressure in the mesenteric artery, with responses to saline occurring during or shortly after the period of injection. Injection of arterialized blood into the artery prompted changes resembling those with saline. Injection of blood for up to 16 sec at a rate which was equal to the resting blood flow in the vessel increased both flow and pressure during the period of injection. Blood flow continued at an elevated level for many seconds after cessation of injection. During this time, pressure in the artery fell to a level below the control value. Calculated mesenteric vascular resistance exhibited a decrease during and following injection. Our findings suggest that the hemodynamic response of the superior mesenteric artery to a pulsation of blood or saline is vasodilation.

Animals↗
PubMed2006

Accuracy of needle placement in ACJ injections.

Localization of the Acromioclavicular joint (ACJ) even at arthroscopic surgery may be difficult because of its small size, osteophytes, variable anatomy of the joint and capsule. Therefore injection of the ACJ in the clinic may well be inaccurate. The aim of this study was to review the clinical accuracy of needle placement in ACJ injections, if performed without the aid of image intensification. Sixty patients with 66 shoulders were injected in the Day Unit in our department. The joint was palpated clinically, and the needle was placed in the site thought to be in the AC Joint. An image intensifier was then used to check the position of the needle in the AP and axillary views. The needle was considered correctly placed if between the bony boundaries of the acromion and clavicle. This was found in only 26 injections (39.4%). The remaining 40 injections (60.6%) were misplaced, either laterally in 21 injections (31.8%), medially in 13 (19.8%), anteriorly in 3 (4.5%) and inferiorly in 3 injections (4.5%). Theses were then reinserted under image intensifier guidance. The misplaced injections would have lead to inaccurate clinical outcomes, and decision making. This study is similar to other studies in that X-ray guidance improves the accuracy of injections and surgery. However the potential error rate for the small, anatomically variable AC joint is high. There is a 60% potential for ACJ injections to be out of the joint if performed by palpation alone, and we recommend the routine use of image intensification guidance.

Acromioclavicular Joint↗
PubMed1999

MR imaging after therapeutic injection of the subacromial bursa.

OBJECTIVE: As a therapeutic injection into the subacromial bursa (SAB) is commonly performed for impingement syndrome, it is important to know whether this fluid can be retained for a period of time and cause confusion with a pathologic collection of fluid. This study identifies and describes the appearance of recent subacromial injection using MR imaging, and the appearance of a potential complication. DESIGN AND PATIENTS: Fourteen asymptomatic shoulders were studied with MR imaging using fast spin echo T2-weighted imaging (1.5 T) prior to injection with 7 cm(3) of xylocaine. Four shoulders had subacromial fluid and were eliminated from the study. The remaining 10 (9 men, 1 woman; age range 27-36 years, average age 33 years) were then re-imaged immediately, and at 6, 12 and 24 h after the injection or until fluid resolved. Each set of images was reviewed for the presence of fluid in the SAB and for additional abnormalities. RESULTS: Fluid was identified in all subjects in the SAB in the immediate, 6 and 12 h post-injection images. At 24 h, fluid was not identified within the SAB in eight of 10 patients. In one patient fluid resolved in 48 h. The other continued to demonstrate fluid in the SAB and in the joint as well as abnormal signal in the infraspinatus muscle from a presumed myositis. Imaging was performed up to 10 days after the injection in this patient. CONCLUSIONS: It is known that fluid identified in the SAB without evidence of a cuff tear may be due to bursitis. However, if MR imaging is performed within 24 h of injection, the presence of the fluid may be iatrogenic. In addition, the history of recent therapeutic injection is very important as complications such as myositis can occur as a result of the injection. Knowledge of injection prior to imaging is vital for accurate interpretation of MR shoulder examinations.

Acromion↗
PubMedDate not supplied

Hepatic CT enhancement: effect of the rate and volume of contrast medium injection in an animal model.

BACKGROUND: To evaluate the relative effect of rate of injection and volume of contrast medium on aortic, portal, and hepatic enhancement during computed tomography (CT). METHODS: Thirty-eight nonincremental CT examinations were performed in three mini-pigs by using a combination of three different volumes (1.5, 2, and 3 mL/kg) and five different rates (1.5, 3, 4.5, 6, and 7.5 mL/s) of contrast material injection. Time-density enhancement curves of the aorta, portal vein, and liver were plotted over time for each rate of injection, each volume of contrast, and each volume-rate combination. In addition, aortic, portal, and liver peak enhancements, time-to-peak enhancements, optimal scanning intervals, and contrast enhancement indices were calculated for each volume-rate combination. RESULTS: Higher rates of injection increased peak aortic enhancement but had no effect on peak portal or hepatic enhancement. This result may be explained by the dilution of the bolus of contrast medium in the splanchnic circulation. When the results of a 6-mL/s injection of 1.5 mL/kg of contrast material were compared with a 3-mL/s injection of 2 mL/kg, maximum aortic enhancement increased by 32%, whereas maximum liver enhancement decreased by 35%. CONCLUSION: An increase in the rate of contrast injection results in an increase of peak aortic enhancement even when the total iodine load is decreased. However, an increase of the rate of contrast injection does not increase maximum liver enhancement, which is related to the total iodine dose injected. Therefore, one cannot compensate a decrease in the iodine load by an increase in injection rate in contrast-enhanced CT of the liver.

Animals↗
PubMed2002

Intravenous calcium injection test is a novel complementary procedure in differential diagnosis for gastrinoma.

The current study evaluated efficacy of the intravenous calcium injection test as a new diagnostic approach to clarify the existence of gastrinoma, which often goes undetected with routine testing. Twenty-six patients with hypergastrinemia were studied. For the calcium injection test, blood samples were taken from 12 patients with hypergastrinemia (HG), and three healthy volunteers, and one patient with nonfunctioning endocrine tumor in the pancreas (control). We compared results of the calcium injection test with those of the secretin test and the selective arterial secretagogue injection (SASI) test. The SASI test with secretin was performed in 24 of 26 patients with hypergastrinemia, including 22 of 24 patients with Zollinger-Ellison syndrome (ZES). Accuracy in the diagnosis of tumor localization by the SASI test was 95% (21 of 22) in ZES patients. The secretin test was negative in 3 of 21 patients with ZES (14%). Either the secretin test or the SASI test was positive in 22 of 23 patients (96%). The calcium injection test was administered to 12 patients in the HG group and 4 controls. The HG group showed significantly higher serum gastrin levels than those of the control group in the calcium injection test. Eight of 10 ZES patients (80%) had a positive calcium injection test. We could diagnose gastrinomas in 100% of ZES patients by either the calcium injection test or the secretin test. We have thus confirmed the efficacy of the intravenous calcium injection test in the diagnosis of gastrinoma. The calcium injection test could become an adjunct in the diagnosis of gastrinoma, which often goes undetected with routine testing.

Adult↗
PubMed2004

Synovial response to intraarticular injections of hyaluronate in frozen shoulder: a quantitative assessment with dynamic magnetic resonance imaging.

To clarify the response of frozen shoulder (FS) to intraarticular injections of high-molecular-weight sodium hyaluronate (HA), a mixture of 2.5 ml of HA and 1.5 ml of 1% lidocaine was injected into the glenohumeral joint of 11 patients with FS, 8 of whom received five weekly injections. The patients were assessed using the Japanese Orthopaedic Association shoulder score (JOA score) before the first injection, 1 week after the first injection, and 1 week after the final injection. Following each clinical evaluation, the patients underwent dynamic magnetic resonance imaging enhanced with Gd-DTPA, and the coefficient of enhancement (CE) in the glenohumeral synovium was calculated, with the examiners blinded to the clinical information. The JOA score tended to be greater and the CE smaller after injection than before injection. The changes in the CE following both single and repeated injections were negatively correlated with changes in the JOA score. Thus, clinical improvement in patients with FS was associated with a decrease in the CE. Because the CE depends on the degree of synovitis, the therapeutic effect of intraarticular HA injection for FS results, at least in part, from suppression of synovitis in the glenohumeral joint through an antiinflammatory effect.

Aged↗
PubMed1978

Spontaneous and amphetamine-induced behavior after bilateral injection of ethanolamine-O-sulfate into the substantia nigra.

Injections of ethanolamine-O-sulfate (EOS) (200 microgram/kg) through chronic indwelling cannulae into the zona reticulata of the substantia nigra in rats produced immediate contraversive turning (away from the injection side). Bilateral injections produced spontaneous stereotyped behaviors including sniffing and biting. Twenty-four hours after the first injection of EOS the rats showed a significantly decreased locomotor response to 1.5 mg/kg D-amphetamine. The spontaneous behaviors elicited following the initial injection of EOS increased both in nature and duration with the second and third injections of EOS, and persevered for 24 h. At this time 1.5 mg/kg D-amphetamine intensified this spontaneous stereotyped behavior. GABA levels were significantly higher in substantia nigra, hypothalamus, corpus striatum and cerebral cortex 24 h following single or repeated (3 x) injections of 200 microgram/kg of EOS into the zona reticulata of the SN. Dopamine levels in the corpus striatum were unchanged 24 h following the EOS treatment except by the injection procedure itself. Control injections into the thalamus produced no turning or stereotypy, nor an enhanced response to 1.5 mg/kg D-amphetamine. GABA levels were, however, significantly higher in the substantia nigra and thalamus 24 h following repeated injections (3 x) of EOS into the thalamus. Results are consistent with the hypothesis that GABA containing neurons comprise part of the efferent output of the corpus striatum and do not act exclusively through a dopaminergic substrate.

Animals↗