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PubMed1991

Characterization of the carboxyl-terminal sequences responsible for protein retention in the endoplasmic reticulum.

The COOH-terminal sequence KDEL has been shown to be essential for the retention of several proteins in the lumen of the endoplasmic reticulum (Munro S., and Pelham, H. R. B. (1987) Cell 48, 899-907; Pelham, H. R. B. (1988) EMBO J. 7, 913-918; Mazzarella; R. A., Srinivasan, M., Haugejorden, S. M., and Green, M. (1990) J. Biol. Chem. 265, 1092-1101). We have previously demonstrated that variants to the KDEL retention signal, particularly at the initial two positions of the tetrapeptide, can be made without affecting its ability to direct intracellular retention when appended to the neuropeptide Y precursor (pro-NPY) (Andres, D. A., Dickerson, I. M., and Dixon, J. E. (1990) J. Biol. Chem. 265, 5952-5955). To further investigate the nature of the KDEL retention signal, oligonucleotide-directed mutagenesis and transfection was used to generate stable mouse anterior pituitary AtT-20 cell lines expressing pro-NPY mutants with variants of the KDEL sequence added to their direct carboxyl terminus. Analyses of dibasic processing and indirect immunofluorescent microscopy of AtT-20 subclones were consistent with the retention of the pro-NPY mutants bearing the COOH-terminal extensions QDEL, KEDL, or KDEI within the endoplasmic reticulum. A change in the final amino acid of the tetrapeptide from Leu to Val abolished retention completely, and the peptide hormone was processed and secreted. These results indicate that only a limited number of conservative changes can be made to the final two positions of the tetrapeptide without abolishing activity and suggest a highly specific interaction of the retention signal and the KDEL receptor.

Amino Acid Sequence↗

PubMed2006

Dependence of cardiac 11C-meta-hydroxyephedrine retention on norepinephrine transporter density.

UNLABELLED: The norepinephrine analog (11)C-meta-hydroxyephedrine (HED) is used with PET to map the regional distribution of cardiac sympathetic neurons. HED is rapidly transported into sympathetic neurons by the norepinephrine transporter (NET) and stored in vesicles. Although much is known about the neuronal mechanisms of HED uptake and retention, there is little information about the functional relationship between HED retention and cardiac sympathetic nerve density. The goal of this study was to characterize the dependence of HED retention on nerve density in rats with graded levels of cardiac denervation induced chemically with the neurotoxin 6-hydroxydopamine (6-OHDA). METHODS: Thirty male Sprague-Dawley rats were divided into 6 groups, and each group was administered a different dose of 6-OHDA: 0 (controls), 7, 11, 15, 22, and 100 mg/kg intraperitoneally. One day after 6-OHDA injection, HED (3.7-8.3 MBq) was injected intravenously into each animal and HED concentrations in heart and blood at 30 min after injection were determined. Heart tissues were frozen and later processed by tissue homogenization and differential centrifugation into a membrane preparation for in vitro measurement of cardiac NET density. A saturation binding assay using (3)H-mazindol as the radioligand was used to measure NET density (maximum number of binding sites [B(max)], fmol/mg protein) for each heart. RESULTS: In control animals, NET B(max) was 388 +/- 23 fmol/mg protein and HED heart uptake (HU) at 30 min was 2.89% +/- 0.35 %ID/g (%ID/g is percentage injected dose per gram tissue). The highest 6-OHDA dose of 100 mg/kg caused severe cardiac denervation, decreasing both NET B(max) and HED HU to 8% of their control values. Comparing values for all doses of 6-OHDA, HED retention had a strong linear correlation with NET density: HU = 0.0077B(max) -0.028, r(2) = 0.95. CONCLUSION: HED retention is linearly dependent on NET density in rat hearts that have been chemically denervated with 6-OHDA, suggesting that HED retention is a good surrogate measure of NET density in the rat heart. This finding is discussed in relation to clinical observations of the dependence of HED retention on cardiac nerve density in human subjects using PET.

Animals↗

PubMed1990

[The effect of calcium and vitamin D deficiency in the food on the uptake and retention of 99mTc-methylenediphosphonate and 85Sr in the bones in rats].

The effects of vitamin D-free diet with low Ca content on 24 hours' 99mTc-methylendiphosphonate retention (in the whole body and tibia), long-term the whole body 85Sr retention and 2 hours' 85Sr catchment in epiphysis, metaphysis and diaphysis of femur and tibia in rats (at the same time in certain experiments femur density and weight after incineration were established) were followed. The whole body 99mTc-MDP retention increases significantly as early as the third day of the diet administration, retention in tibia and the whole body is in further 2 experiments increased after 1, 2 and 4 weeks of the diet (density decreases from the first or the second week). The whole body 85Sr retention is significantly increased as early as after 2 days of the diet, the great difference against controls only slowly decreases after discontinuation of low-Ca diet. Further experiment followed 2 hours' 85Sr catchment in femur and tibia samples after 2, 5, 10 and 20 days of diet--catchment increase is significant after 20 days (bone density and ash weight is significantly decreased after 10 and 20 days of diet). Thus retention of both osteotrophic substances in bone is as a result of low Ca diet increased. This reaction is in case with 85Sr expected, in that of 99mTc-MDP it suggests a possible relation of the catchment and mineral component of osseous tissue. Increased retention of both the substances obviously fails to be related to local blood circulation which was in this situation in our previous experiments decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

[Protein retention in relation to age].

Male Norway rats of the Wistar strain, aged 30, 75, 90, 150, 180, and 360 days, were given ad libitum diets with optimum nutrient contents at every age. Determining the net protein utilization, the values of protein retention were calculated from protein intake. The energy demand per unit of protein retention was determined from the saccharide and fat intake. The energy ratios of proteins, fat, and saccharide were calculated from the optimum nutrition values; this ratio was 13:(57-29):(30-58) in the period of rapid growth (30-90 days old animals). 12:28:60 in the period of maturing (slower growth, 150 days old animals), and 10.5:28:61.5 at maturity (finished growth, 180-360 days old animals). The daily weight gains of the animals given optimum diets (5.52, 5.22, 5.09-3.73-2.11, 1.85 g daily) and the values of protein retention also corresponded to the division of the animals according to their growth (after administration of the standard Larsen diet). In the period of rapid growth, protein retention was increasing up to the age of 90 days--this suggests that the proteins are utilized for building the body and for its development. A decrease in protein retention in 150 days old animals means that the animals have entered the stage of slow growth. Finally, the low retention values at adult age suggest that the proteins are utilized only for the regeneration of worn tissues and for maintenance. It is indicated by the higher values of energy demand per unit of body protein retention at adult age that more energy (mainly the energy of saccharides--starch) is needed to secure the processes of tissue maintenance and regeneration.

Aging↗

PubMed1988

Monocyte retention and migration in pulmonary inflammation. Requirement for neutrophils.

The acute inflammatory process is characterized by an orderly progression of events; an initial phase of early neutrophil accumulation and a later phase of mononuclear cell (including monocyte) accumulation. The mechanisms which control the transition from one phase to the other are largely unknown. We present a rabbit model of C5 fragment (C5f)-induced lung inflammation in which purified radiolabeled peripheral blood neutrophils and monocytes were used as probes to monitor the retention and emigration of these leukocytes into well localized areas of inflammation. Neutrophil preparations (greater than 95% pure) were isolated by discontinuous plasma-Percoll density gradients, and monocyte preparations (greater than 91% pure) were isolated by counterflow cell elutriation, labeled with 111Indium-tropolonate, and intravenously infused into separate recipient animals. The monocytes circulated with a half-life of approximately 30 hours. The retention of labeled monocytes or neutrophils within the lung was monitored scintigraphically. C5f-induced monocyte lung retention was delayed 2 to 4 hours compared with neutrophil lung retention. Radiolabeled neutrophils were selectively retained in the area of C5f-induced inflammation (right cranial lung lobe, RCL) as early as 20 minutes after the induction of the inflammatory response, reached a maximum by 2 hours, and were not retained by 48 hours after C5f instillation. The signal inducing C5f-induced monocyte lung retention was shown to be transient. Monocytes were selectively retained in the RCL if the area of inflammation was induced 2 to 4 hours but not 15 minutes or 16 hours before their infusion. The time course of C5f-induced monocyte migration into the alveolar space determined by lavage analysis was delayed 2 to 3 hours compared with neutrophil migration. Neutrophils selectively migrated into the RCL 1 to 2 hours after the induction of the inflammatory response, reached a maximum by 4 hours, and had disappeared by 48 hours. Radiolabeled monocytes selectively migrated into the RCL 3 to 4 hours after the induction of the inflammatory response, reached a maximum by 4 hours, and remained present through 48 hours. The total number of labeled and unlabeled mononuclear cells present in the C5f-treated RCL lavage at 48 hours was significantly increased above controls. The signal for this monocyte migration (as for lung retention) was shown to be transient in that radiolabeled monocytes did not migrate when infused 16 hours after the induction of the inflammatory response. C5f did not induce monocyte lung retention nor monocyte migration into the alveolar space of animals rendered neutropenic.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1980

[Physical properties of resins for veneer crown. (Part 2) Bending strength and retention force of opaque resins (author's transl)].

The retention force of 9 kinds of resins for veneer crown, physical properties and retention force of 7 kinds of opaque resins were determined. Retention force and their physical properties were closely related on resins for veneer crown, that is stronger and more tough resins have larger retention force. The opaque resins containing larger quantity of filler and hydrophilic monomers showed extra-ordinary young's modulus afteter drying. But young's modulus and strength decreased after immersed in water and thermal cycling and the retention force also decreased to the smallest level after immersed in water and thermal cycling. The hydrohobic opaque resins that have good coupling effect to filler showed large retention force even after immersed in water and thermal cycling in spite of large filler content. The opaque resins containing MMA with scanty filler showed large elongation and breaking strength and their retention force were also large after immersed in water and thermal cycling.

Color↗

PubMed1981

[Retention of three different luting cements (author's transl)].

Employing zinc phosphate, polycarboxylate and glass ionomer cements, effect of cement layer thickness on retention of crowns at their axial wall was investigated. Stainless steel preparations and occlusally perforated crowns having taper angles of 2.9 and 5.7 degrees were cemented, regulating the thickness at the axial wall from 5 to 60 mu. These dies were stored in a 100% relative humidity atmosphere at room temperature or in distilled water. After 48 hr, retention was measured, applying the load vertically to occlusal preparation surface through a plunger (Fig. 1). Due to the inclusion of unreacted powder particles in the set structure of all three cements, evidence of a critical value was always shown in the cement thickness-retention relationship (Figs. 2, 3 and 4). When the cement thickness was reduced below the critical value, the retention increased remarkably and was not affected by the environment. Above the critical value, however, the retention of these cements was relatively small and affected considerably by the environment. By water immersion, the increase in the retention was found for the two polyacrylate, but not for the zinc phosphate. Correlation between retention and mechanical strengths of the three cements in the respective environments was indefinite.

Adhesiveness↗

PubMedDate not supplied

The significance of sieve-retention to the filter validation process.

Current efforts at filter validation involve the need to test under "worst case conditions" the bacterial retentive action of filters utilizing the very drug being processed. These concerns recognize that the adsorptive retentions of organisms vary in their efficiencies, depending upon the filtration conditions and the presence or absence of surfactant. The sieve retention of organisms is independent of such conditions, deriving solely from considerations of organism-size, pore-size relationships. Flow-decay studies, can serve to differentiate between filter actions based on sieve-retentions and adsorptive-retentions. A filter's dependence solely upon sieving effects is demonstrable. What is involved is a plotting of flow rates as a function of time in accordance with established mathematical equations. Appropriate plots would indicate the exclusive sieve retention of organisms, a condition of absolute filter reliability deriving from organism-pore size relationships. The clear demonstration by a filter company that its sterilizing filter retains organisms solely by the sieve retention mechanism would suffice to validate that filter for all pharmaceutical filtrations, eliminating the need for individual user validations. The advantage of this mode of filter validation, one based on structurally-inherent filter pore architecture, is that pharmaceutical manufacturers would be free from the need to validate a given filter for each and every pharmaceutical preparation. This would also simplify the FDA's confirmation of filter validation, since a single inspection of the filter manufacturer's records would suffice for all the filter's users.

Adsorption↗

PubMed1995

Effect of graded hypoxia on retention of technetium-99m-nitroheterocycle in perfused rat heart.

UNLABELLED: The purpose of this investigation was to determine the effects of graded hypoxia on the retention of a 99mTc-labeled nitroimidazole. METHODS: Rat hearts were perfused retrogradely with Krebs-Henseleit buffer at 37 degrees C and paced at 5 Hz. After a 20-min stabilization period, coronary flow was maintained at 8 ml/min/g wet wt and the hearts were perfused with media equilibrated with gas mixtures containing 5% CO2 and various levels of O2, from 544 to 29 Torr. Technetium-99m-O(PnAO-1-(2-nitroimidazole)), BMS-181321, was infused for 20 min into a side port of the aortic cannula. Perfusion continued for an additional 40 min to allow for compound clearance. RESULTS: Each decrease of perfusate PO2 brought about an increase in the retention of BMS-181321, resulting in a good correlation between its retention and perfusate PO2 (r = 0.97). Myocardial oxygen consumption was independent of oxygen delivery when the perfusate oxygen pressure was greater than 350 Torr. Below this value, oxygen consumption declined markedly as influent PO2 was decreased. By contrast, the tissue lactate/pyruvate ratio and lactate efflux rose with each decrease of influent PO2. A good correlation was obtained between retention of the nitroheterocycle and the cytosolic lactate/pyruvate ratio (r = 0.98). When glucose was omitted from the perfusate (PO2 = 27 Torr), retention of the nitroheterocycle was increased by about 25% as compared to hearts perfused in the presence of this substrate. CONCLUSION: These results indicate that myocardial retention of BMS-181321 is coupled to the level of tissue oxygenation and that hypoxic retention may be affected by substrate input.

Animals↗

PubMed1993

Specific sequences in the signal anchor of the beta-galactoside alpha-2,6-sialyltransferase are not essential for Golgi localization. Membrane flanking sequences may specify Golgi retention.

The beta-galactoside alpha-2,6-sialyltransferase is a trans Golgi/trans Golgi network glycosyltransferase which adds sialic acid residues to Asn-linked oligosaccharides of glycoproteins. Previous results suggested that the sialyltransferase stem and signal anchor including flanking sequences may be two independent Golgi retention regions. However, other experiments demonstrated that the sequence of the signal anchor itself was not important. To investigate whether the sialyltransferase signal anchor was necessary and sufficient for Golgi retention, several mutant and chimeric proteins were expressed and localized in Cos-1 and Chinese hamster ovary cells. We found that the signal anchor and flanking sequences were able to retain the sialyltransferase catalytic domain in the Golgi. However, efficient Golgi retention was still observed when the signal anchor was altered or entirely replaced in either the presence or absence of most of the luminal stem region. Chimeric proteins consisting of the sialyltransferase cytoplasmic tail and signal anchor fused to the extracellular domains of two different cell surface proteins demonstrated poor Golgi retention. A significant increase in the Golgi retention of one of these chimeras was observed when two lysines were placed next to the signal anchor on the luminal side. Taken together these results suggest that the sialyltransferase signal anchor is not necessary or sufficient for Golgi retention, rather, appropriately spaced cytoplasmic and luminal flanking sequences are the important elements of the sialyltransferase Golgi retention region.

Amino Acid Sequence↗

PubMed1994

Sodium retention does not occur at a critical threshold of liver function in alcoholic cirrhosis.

Sodium retention is triggered in rats with experimental liver injury at a critical threshold of liver function. We compared liver function and sodium retention in serially studied patients with alcoholic cirrhosis to determine whether a similar threshold exists in human beings. Antipyrine, caffeine, and cholic acid clearance were measured in 35 men with alcoholic liver disease. Nineteen patients were evaluated on two or more occasions; between studies, 28 remained in sodium balance (group NN), six spontaneously developed sodium retention and ascites formation (group NY), and seven spontaneously lost ascites (group YN). A threshold between patients with and without sodium retention did not exist for any of the clearance measurements. Indeed, values overlapped widely between the two groups. Antipyrine and cholate clearance were significantly reduced in patients with sodium retention, but caffeine clearance was similar in the two groups. Antipyrine and caffeine clearance declined significantly between the first and second study in group NY; cholate clearance did not change. No significant differences were observed between studies in group YN. In several patients of this group, liver function worsened as ascites spontaneously resolved. Impaired liver function commonly but not invariably accompanies sodium retention in patients with cirrhosis. A threshold at which sodium retention occurs or resolves does not exist.

Antipyrine↗

PubMed1993

[Postprandial serum bile acid level and 75SeHCAT retention in diagnosis of bile acid malabsorption syndrome. A comparative study].

Postprandial serum bile acids (expressed as integrated bile acid response [IR]) after a standardized test meal were compared with 75SeHCAT retention, measured in a whole body counter, in healthy controls (n = 20), in 44 patients with ileal disease or resection and in 23 patients with colitis without ileal involvement. In the controls the IR after 180 min was 736 +/- 186 mumol x min x 1(-1) (mean +/- standard deviation), the 75SeHCAT retention 31 +/- 9%. 80% of the patients with ileal disease or resection had a decreased 75SeHCAT retention, indicating bile acid malabsorption, but only 59% had a diminished IR. One of the 23 patients with colitis and radiologically normal ileum had a decreased 75SeHCAT retention but a normal IR, reflecting a dysfunction of the morphologically normal ileum. The characteristics of the two tests are: 75SeHCAT retention test: sensitivity 80%, specificity 98%, accuracy 89%; postprandial serum bile acids: sensitivity 64%, specificity 74%, accuracy 69%. With respect to chronic inflammatory bowel disease the positive predictive value of the 75SeHCAT retention test is 1.0%, for postprandial serum bile acids 0.1%, whereas the negative predictive values amount to 99% for both tests. Thus 75SeHCAT retention is more reliable in detecting bile acid malabsorption than the determination of postprandial serum bile acids, although both tests are not usefull for screening the population for ileal disease.

Adolescent↗

PubMed1996

Retention and stability considerations for adult patients.

This article gives an overview of generally accepted and special concepts of the last and often life-long treatment-phase in adult orthodontics, the retention phase. The secret of successful adult orthodontics lies in adult-specific principles of histology and physiology and the interrelation of joint, occlusion, and muscles, which helps define the requirements of proper diagnosis, mechanics, and retention. Retention in adults should include maintenance of tooth position, overall dental health, and a periodontal status that can be attained by combinations of several retention concepts: retention appliances and surgical and restorative retention procedures. Short- and long-term postretention follow-up studies have shown that there is no guarantee for long-life stability after orthodontic tooth movements in adults without an anomaly- and treatment--specific retention phase.

Adult↗

PubMed1996

Evaluation of disc retention of Björk-Shiley Delrin heart valves.

BACKGROUND AND AIMS OF THE STUDY: Impact wear grooves have been observed in the occluder discs of clinically explanted Björk-Shiley Delrin (BSD) heart valves due to repetitive closing impacts against the inlet strut. We examined whether this impact wear could increase the disc-to-strut gap, which could in turn affect the retention of occluder disc. MATERIALS AND METHODS: Three BSD heart valves with deep wear grooves were tested in a left ventricular assist device set-up simulating dynamic conditions that would facilitate the dislodgement. RESULTS: The disc was found to be rotating within the flange during the testing and no embolization of the occluder disc occurred in any of the BSD valves tested. The Björk retention limit and the physical retention limit were calculated for each valve. The Björk retention limit is defined as (disc well depth)-(disc-to strut gap)-(1/2 outlet strut wire diameter) and the physical retention as (disc well depth)-(disc-to strut gap). CONCLUSION: The disc retention would not be affected by the impact wear grooves as long as the disc-to-strut gap did not exceed the physical retention limit.

Biocompatible Materials↗

PubMedDate not supplied

Retention of adoptively transferred interleukin-2-activated natural killer cells in tumor tissue.

BACKGROUND: Adoptively transferred interleukin-2 activated natural killer (A-NK) cells are capable of selectively infiltrating tumor, however, only at low efficiency. The aim of this study was to investigate the intratumoral A-NK cell retention using an ex-vivo tissue-isolated tumor preparation. METHODS: R3230AC mammary adenocarcinoma and CSE fibrosarcoma were implanted in the ovarian fat pad of Fisher 344 rats. The tumors were perfused ex vivo 14 to 15 days post-implant with a known number of fluorescent labelled A-NK cells, and the effluent collected serially over time. Non stimulated splenocytes (N-SS) were used as controls. RESULTS: In group 1, tumors were perfused with either A-NK (n = 16) or N-SS (n = 7) cells. The mean number of the cells which remained intratumorally at the completion of the perfusion was 48.37% +/- 14.94 for A-NK cells and 34.68% +/- 13.20 of N-SS (p = 0.048). In group 2, tumors were perfused with a suspension containing both A-NK and N-SS cell (n = 11). The difference in tumor retention between A-NK cells and N-SS was 22.5% (p = 0.0053) for R3230AC tumors (retention of intratumoral A-NK cells was 45.1% +/- 6.47 vs. 22.6% +/- 19.09 for N-SS) and 15.88% (p = 0.028) for the fibrosarcomas (34.01% +/- 15.96 vs. 18.12 +/- 17.78 for A-NK and N-SS, respectively). No difference with respect to retention of A-NK cells or N-SS cells was observed between tumor types (p = 0.23 and p = 0.71, respectively). CONCLUSIONS: The retention of A-NK cells in tumor tissues was significantly better than the retention of N-SS when administered directly. Since the retention of A-NK cells in tumor tissue was high (35-50%), this factor does not explain the low efficiency of adoptively transferred A-NK cells accumulating in tumors when administered systemically.

Adoptive Transfer↗

PubMed1977

Acquisition and retention of a passive-avoidance task as a function of age in mice.

In Experiment I groups of mice between 16 to 100 days of age were tested for retention of a passive-avoidance response between 1 min and 96 hr following a single training trial at 2 shock intensities. In general, although almost all age groups displayed reliable retention at all retest intervals, some retention losses were found among the youngest age groups at the longer retention intervals. Higher shock intensity resulted in longer retest latencies, primarily among the youngest mice. In Experiment II mice 16, 25, and 100 days of age were trained to criterion on the passive-avoidance task and retested on a single trial following retention intervals of 24, 96, 192, and 384 hr. Young mice exhibited severe retention losses relative to 100-day-old mice at the longer intervals, even though they did not show deficiencies in acquisition. Neurological maturity at the time of original training appears to account for the age-related memory differences.

Age Factors↗

PubMed1999

Effects of posttraining administration of insulin on retention of a habituation response in mice: participation of a central cholinergic mechanism.

Male Swiss mice were allowed to explore a novel environment, provided by an open-field activity chamber for a 10-min period. The procedure was repeated twice within a 24-h interval. The difference in the exploratory activity between the first (training) and the second exposure (testing) to the chamber was taken as an index of retention of this habituation task. Posttraining intraperitoneal administration of insulin (8, 20, or 80 IU/kg) impaired retention in a dose-related manner, although only the dose of 20 IU/kg of insulin produced significant effects. Thus, the dose-response curve adopted a U-shaped form. Insulin (20 IU/kg) given to untrained mice did not modify their exploratory performance when recorded 24 h later. The effects of insulin on retention were time dependent, suggesting an action on memory storage. An ineffective dose (8 IU/kg) of insulin given together with an ineffective dose of a central acting muscarinic cholinergic antagonist atropine (0.5 mg/kg) or with a central acting nicotinic cholinergic antagonist mecamylamine (5 mg/kg) interacted to impair retention. In contrast, neither methylatropine (0.5 mg/kg), a peripherally acting muscarinic receptor blocker, nor hexamethonium (5 mg/kg), a peripherally acting nicotinic receptor blocker, interacted with the subeffective dose of insulin on retention. The impairing effects of insulin (20 IU/kg) on retention were reversed by the simultaneous administration of physostigmine (70 microg/kg) but not neostigmine (70 microg/kg). We suggest that insulin impairs memory storage of one form of learning elicited by stimuli repeatedly presented without reinforcement, probably through a decrement of brain acetylcholine synthesis.

Animals↗

PubMed1977

Effects on retention of posttraining amphetamine injections in mice: interaction with pretraining experience.

These experiments examined the effects of d-amphethamine on retention of one-trial inhibitory (passive) avoidance training in mice. Water-deprived mice were pretrained to lick from a water spout at the end of a darkened compartment. Footshock was administered during licking after 4, 6, or 7 days of pretraining. Retention performance (latency to lick) was measured 24 h after training. The effects on memory of posttraining amphetamine varied not only with amphetamine dose but also with the amount of pretraining. In animals pretraining for 7 days, 0.3 and 1.0 mg/kg but not 0.03, 0.1, or 3.0 mg/kg posttraining amphetamine significantly enhanced later retention performance. In mice pretrained for 6 days, 1 mg/kg amphetamine also enhanced retention performance. However, in mice pretrained for only 4 days, 1 mg/kg amphetamine impaired later retention erd for only 4 days, 1 mg/kg amphetamine impaired later retention performance. These results are consistent with the view that posttraining treatment may affect memory storage processes by interacting with training-related arousal levels.

Animals↗