Relationship of hyaluronan and HYBID (KIAA1199) expression with roughness parameters of photoaged skin in Caucasian women.

BACKGROUND: Hyaluronan (HA) is an important constituent of extracellular matrix (ECM) in the skin, and HA degradation mediated by HYBID (KIAA1199) is suggested to be implicated in facial skin wrinkling in Japanese women. Ethnic difference in skin wrinkle formation is known between Caucasian and Japanese women, but no information is available for the relations of HA and HYBID expression levels with skin wrinkling in Caucasian women. METHODS: The skin surface roughness at the eye corner of the Caucasian female subjects was measured, and the skin specimens biopsied from the same areas were subjected to microarray gene analysis, HA staining, and immunohistochemistry for HYBID. RESULTS: Among the ECM genes and those related to ECM metabolism, only HYBID expression levels positively correlated with the skin roughness parameters. When the skin sample groups with high expression of HYBID or low expression of HYBID were compared, the HA staining intensity and the ratio of HYBID-immunoreactive cells to total cells in the superficial dermis were significantly reduced and increased in the high-HYBID-expression group compared with the low-HYBID-expression group, respectively. CONCLUSION: Our data suggest that like Japanese women, HYBID-mediated reduction of HA in the superficial dermis is involved in the formation of wrinkles in Caucasian women.

Reduction of hyaluronan and increased expression of HYBID (alias CEMIP and KIAA1199) correlate with clinical symptoms in photoaged skin.

BACKGROUND: Hyaluronan (HA) metabolism in skin fibroblasts is mediated by HYBID (hyaluronan binding protein involved in hyaluronan depolymerization, alias CEMIP and KIAA1199) and the HA synthases HAS1 and HAS2. However, photoageing-dependent changes in HA and their molecular mechanisms, and the relationship between HA metabolism and clinical symptoms in photoaged skin remain elusive. OBJECTIVES: We examined the amount, size and tissue distribution of HA and expression levels of HYBID, HAS1 and HAS2 in photoaged skin, and analysed their relationship with the degree of photoageing. METHODS: Photoageing-dependent changes of HA were investigated by studying skin biopsies isolated from photoprotected and photoexposed areas of the same donors, and the relationships between HA and photoageing symptoms such as skin wrinkling and sagging were examined. RESULTS: Skin biopsy specimens showed that the amount and size of HA are decreased in photoexposed skin compared with photoprotected skin, and this was accompanied by increased expression of HYBID and decreased expression of HAS1 and HAS2. Histologically, HA staining in the papillary dermis was decreased in photoexposed skin, showing reverse correlation with HYBID expression. HYBID expression in the photoexposed skin directly correlated with skin roughness and sagging parameters, and the reduced HA staining in the papillary dermis in the photoexposed skin positively correlated with these symptoms. CONCLUSIONS: These data demonstrate that imbalance between HYBID-mediated HA degradation and HAS-mediated HA synthesis may contribute to enhanced HA catabolism in photoaged skin, and suggest that HYBID-mediated HA reduction in the papillary dermis is related to skin wrinkling and sagging of photoaged skin.

Treating bladder-outflow obstruction with thermo-expandable prostate metal stents.

Bladder-outflow obstruction is a common age-related clinical entity due to a variety of benign and malignant diseases of the prostate. Surgical treatment is not suitable for high-risk elderly patients who seek minimally invasive management. We present a prostatic thermo-expandable metal stent for treating bladder-outflow obstruction. In this review, we include the design characteristics of this novel device, the performance assessment in comparison with alternative devices, the limitations, our personal clinical experience, as well as a long-term perspective. According to our experience among 127 patients (who underwent insertion of 192 stents) after 1, 2 and 3 years, 82, 61 and 47% of the original stents were functional without apparent complications, respectively. The mean single stent indwelling time was 1 year, with a maximum of 4 years. In 41% of patients, the stent needed to be removed and/or exchanged owing to stent encrustation (15%), migration (10%), penile pain (6%), bladder-outflow obstruction symptoms (5%), urinary incontinence (<3%), tissue granulation (<3%), recurrent urinary tract infections (<3%) or urethral stricture (<3%). The thermo-expandable prostatic stent seems to be an effective minimally invasive treatment of bladder-outflow obstruction, especially in high-risk patients.

Molecular targeting of Bcl-2 overcomes prostate cancer cell adaptation to XIAP gene downregulation.

X-linked inhibitor of apoptosis (XIAP) is a suppressor of apoptosis that supports an increased survival and resistance to chemotherapy of human prostate cancer (PCa) cells. Effects of transient (24 h) and chronic (beyond 1 month) downregulation of XIAP in DU145 hormone refractory prostate cancer (HRPC) cells were studied. We found that transient downregulation of XIAP by siRNAs resulted in an increase of apoptosis and a decrease in Bcl-2 levels and sensitized PCa cells to cisplatin. XIAP downregulation by shRNA vector stable transfection led to upregulation of Bcl-2 protein. Our results identify the adaptability of PCa cells to chronic loss of XIAP in part through upregulation of Bcl-2 and indicate that multitargeting approach is the most effective application in the chemotherapy of human HRPC.

Double inhibition of XIAP and Bcl-2 axis is beneficial for retrieving sensitivity of renal cell cancer to apoptosis.

Renal cell carcinoma (RCC) is known to be resistant to chemo- and radiotherapy due to a high apoptotic threshold. Smac and XIAP (X-linked inhibitor of apoptosis protein) proteins were detected in all RCC cell lines and tissue samples examined. We modulated the function of XIAP, either through its constitutional downregulation with an shRNA vector or by applying a Smac-mimicking peptide. Among RCC cell lines, Caki1 expresses the highest levels of XIAP. We transfected Caki1 with XIAP-targeting shRNA vector and generated stable clones. XIAP was knocked down by RNA interference in clone no. 14 by 81.6% and in clone no. 19 by 85.3%. Compared to the parental and mock-transfected cells, neither clone was more sensitive to conventional chemotherapeutic agents, but both clones were more susceptible to Fas stimulation (P<0.0001) and to pharmacological Bcl-2 inhibition (P<0.0001), as well as to a combination of the two (P<0.0001). Mature Smac binds to XIAP via the N-terminal residues, disrupting its interaction with caspases and promoting their activity. We determined that exposure of Caki1 cells to Smac-N7 peptide (AVPIAQK) resulted in a slight but significant decrease in viability (P=0.0031) and potentiated cisplatin's effect (P=0.0027). In contrast with point targeting of XIAP by shRNA, Smac-N7 peptide is active against several IAP (inhibitor of apoptosis protein) family members, which can explain its role in sensitising cells to cisplatin. Our results suggest that multiple targeting of both Bcl-2 and XIAP or, alternatively, of several IAP family members by the Smac-N7 peptide is a potent way to overcome resistance of RCC to apoptosis-triggering treatment modalities, and might be a new tool for molecular targeted therapy.

Hypertensive glomerular damage as revealed by the expression of alpha-smooth muscle actin and non-muscle myosin.

The aim of this study was to determine the phenotypic modulation in mesangial cells of glomeruli damaged by hypertension. Salt-loaded stroke-prone spontaneously hypertensive rats were untreated or treated with a calcium antagonist, manidipine (2 mg/kg/day) for eight weeks. In normotensive Wistar-Kyoto rats, alpha-smooth muscle actin was not expressed in any glomerular cells and a non-muscle myosin heavy chain isoform, SMemb, was slightly expressed in glomerular visceral epithelial cells. In the untreated hypertensive rats, the glomeruli showed sclerosis to various degrees and expressed alpha-smooth muscle actin and SMemb. Normal expression of SMemb in the epithelial cells disappeared. Notably, alpha-smooth muscle actin-positive fibroblast-like cells appeared in the interstitium, especially around the Bowman's capsules. Manidipine ameliorated the glomerulosclerosis and reduced the expression of alpha-smooth muscle actin in mesangial cells. In conclusion, the mesangial cells changed their phenotypes and expressed alpha-smooth muscle actin and SMemb in the glomeruli during the development of hypertensive renal damage. These phenotypically changed mesangial cells are considered to be activated and to produce various kinds of cytokines and extracellular matrix, which leads to glomerulosclerosis. Manidipine attenuated the glomerular damage and the phenotypic changes. The functional relevance of phenotypic changes in these cells should be elucidated in future studies.

[Beneficial effects of the combination of idebenone and manidipine 2HCl on neurological deficits and histological changes following cerebrovascular lesions in stroke-prone spontaneously hypertensive rats].

We investigated the effects of the combination of idebenone, an energy metabolism enhancer, and manidipine 2HCl, a dihydropyridine-derivative calcium antagonist, on neurological deficits and histological changes in the brain and kidneys of stroke-prone spontaneously hypertensive rats (SHRSP) with cerebrovascular lesions (stroke). The SHRSP were kept on a 1% NaCl solution as their drinking water to synchronize the onset of stroke. After the onset of stroke symptoms, the salt solution was replaced with tap water. On the day following the onset of stroke, idebenone (50 mg/kg), manidipine 2HCl (2 mg/kg) or a combination of idebenone (50 mg/kg) and manidipine 2HCl (2 mg/kg) was administered orally once a day for 3 weeks. In the combination group and manidipine 2HCl-treated group, the neurological deficits after the onset of stroke were ameliorated during the entire experimentalperiod. Especially, the combination significantly decreased the number of days with severe neurological deficits as compared to the control group. The combination and manidipine 2HCl significantly recovered the decrease in body weight and ameliorated the increase of brain weight, which was mainly caused by edema, significantly as compared to the control group. Manidipine 2HCl ameliorated the histological changes in the brain. In the combination group, the histological changes in both the brain and the kidneys were ameliorated. In conclusion, the combination of idebenone and manidipine 2HCl significantly ameliorated the neurological deficits and the histological changes in the brain and the kidney of SHRSP with stroke as compared to each individual treatment. We concluded that manidipine 2HCl enhances the therapeutic effect of idebenone in the treatment of cerebrovascular diseases.

Cytochrome P4501A1 gene polymorphism and homozygous deletion of the glutathione S-transferase M1 gene in urothelial cancer patients.

Japanese urothelial (bladder, renal pelvis and ureter) cancer patients (n = 83) and community controls (n = 101) were compared for rates of polymorphism in exon 7 of the cytochrome P4501A1 (CYP1A1) gene or homozygous deletion of the glutathione S-transferase class mu (GSTM1) gene. A CYP1A1 polymorphism was detected in a HinCII polymorphism assay utilizing a primer with a single base pair mismatch. The frequency distribution of the CYP1A1 genotypes in urothelial cancer patients showed no significant difference from that in healthy controls. The increased frequency of homozygous deletions of GSTM1 gene loci in patients with urothelial cancer was statistically significant compared with the controls, 51 of 83 (61%) and 43 of 101 (43%) (odds ratio = .2.15, 95% confidence interval = 1.18-3.86). These results lead us to conclude that homozygous deletion of the GSTM1 gene may be associated with susceptibility to urothelial cancer.

Effects of a sustained release formulation of thyrotropin-releasing hormone on behavioral abnormalities in senescence-accelerated mice.

Effects of a sustained release formulation of thyrotropin-releasing hormone (TRH-SR) on reduced anxiety-like behavior and learning impairment in senescence-accelerated mice (SAM) were examined. SAMP8/Ta (SAMP8) mice showing age-related emotional changes as well as learning and memory impairments, and SAMR1TA (SAMR1) mice exhibiting normal aging were used at 8 months of age. Subcutaneous injection of TRH-SR (2.8 mg/kg as free TRH) produced a sustained increase in immunoreactive plasma TRH levels up to about 4 weeks after dosing in SAMP8. TRH-SR antagonized the reduced neophobia to novel food in SAMP8 in a dose-dependent manner when tested 10 days but not 3 days after the injection. In the elevated plus-maze test, the SAMP8 control group treated with vehicle had significant increases in the number of entries into open arms and the time spent in open arms in comparison to SAMR1 mice. TRH-SR showed dose-dependent decreases in the number of entries into open arms, and reduced the time spent in open arms in SAMP8 mice. Furthermore, TRH-SR significantly improved the impairment of water maze learning in SAMP8 mice. In contrast, bolus administration of TRH had no significant effects on behavioral abnormalities in SAMP8 even at high doses, implying that long-term and continuous infusion of TRH may be important for amelioration of the behavioral abnormalities. These results suggest that TRH-SR may be useful for treatment of age-related emotional disorders and memory disturbance in dementia.

Two cases of urogenital malignancies in male patients undergoing maintenance haemodialysis.

We report two cases of urogenital malignancies, prostatic cancer in a 72-year-old man and urinary bladder carcinoma in a 50-year-old man, that developed during maintenance haemodialysis. The former patient responded to hormonal therapy with diethylstilboestrol and is still alive on maintenance haemodialysis, but the latter patient did not respond to treatment, being past cure in the far advanced stage. There are few clinical symptoms suggesting the existence of urogenital malignancies in dialysis patients and screening methods such as urine cytology or roentgenology must be restricted because of extremely reduced urine volume. However, the high incidence of urogenital malignancies in such patients is well recognized. Screening examinations with ultrasonography and/or CT scan following digital rectal examination or testing for serum prostate-specific antigen should be performed at least every 6 months.

Effects of sustained release formulation of thyrotropin-releasing hormone on learning impairments caused by scopolamine and AF64A in rodents.

The effects of a sustained-release formulation of thyrotropin-releasing hormone (TRH-SR) on learning impairments induced by scopolamine and a cholinergic neurotoxin, ethylcholine aziridinium ion (AF64A), were examined in rodents. Subcutaneous injection of TRH-SR (2.8 mg/kg as free TRH) produced a sustained increase in immunoreactive plasma TRH levels up to about 2 weeks after dosing in rats. TRH-SR (0.56 and 2.8 mg/kg) given subcutaneously 7 days before the acquisition trial markedly ameliorated scopolamine-induced amnesia in mice, as evaluated with a passive avoidance task. Repeated administration of TRH for 7 days at doses of 0.2-5 mg/kg s.c. elicited a dose-dependent recovery from amnesia induced by scopolamine, whereas only the group treated with 5 mg/kg/day showed a significant improvement. The rats with bilateral intracerebroventricular injection of AF64A (3.75 nmol/brain) showed a significant impairment in the water maze task 2 weeks after surgery. TRH-SR (0.56 and 2.8 mg/kg) also exhibited a dose-dependent ameliorating action on the deficit. These findings indicate that TRH-SR ameliorates learning impairments produced by scopolamine and AF64A, and suggest that continuous infusion of TRH may have a potent learning and memory improving action at low doses.

Effect of thyrotropin-releasing hormone on pentobarbitone-induced sleep in rats: continuous treatment with a sustained release injectable formulation.

The mode of action and the time course of the effects of continuous thyrotropin-releasing hormone (TRH) treatment using a two-week sustained release injectable formulation of TRH-containing copoly((+/-)-lactic/glycolic acid) microspheres (TRH-SR) on pentobarbitone-induced sleeping time were studied in rats. Subcutaneous treatment with TRH-SR at doses corresponding to 0.05 and 0.2 mg of TRH kg-1 day-1 caused a dose-related shortening of pentobarbitone-induced sleeping time with a minimum effective dose (MED) of 0.05 mg kg-1 day-1, without affecting the body weight gain. On the other hand, the MED of TRH when given as a bolus subcutaneous injection was 40 mg kg-1. The effect of TRH-SR treatment was blocked by intraperitoneal scopolamine (0.1 mg kg-1) and mecamylamine (2 mg kg-1) but not by scopolamine methyl bromide (0.1 mg kg-1). The results indicate that continuous TRH treatment using TRH-SR causes shortening of pentobarbitone-induced sleeping time at doses lower than those required using bolus injection and probably by a mechanism involving the central cholinergic system.

Pharmacologic characteristics of a new calcium antagonist, manidipine: beneficial effects on renal circulation and vascular changes.

The calcium antagonist, manidipine, was developed on the basis of the hypothesis that antihypertensive drugs that act to improve renal hemodynamic alterations will be therapeutically beneficial in hypertensive patients. Manidipine shows long-lasting calcium channel-blocking action in vascular smooth muscle cells and antihypertensive actions in various types of hypertensive models. The drug has high selectivity for resistance vessels, dilates renal vasculature, and inhibits renal vascular constrictions induced by norepinephrine and angiotensin II in spontaneously hypertensive rats. It increases renal blood flow and has a prominent natriuretic action without changing glomerular filtration rate. The coronary dilating effect of the drug is similar to that of nifedipine, but its cardiodepressant effects are less potent than those of other dihydropyridines. Furthermore, manidipine prevents the development of cerebrovascular lesions and inhibits the progression of vascular damage in the brain and kidneys of stroke-prone spontaneously hypertensive rats. The drug also inhibits a proliferative response of the intima to balloon catheter-induced injury in the carotid arteries of spontaneously diabetic rats without affecting plasma lipids or blood pressure. These results suggest that manidipine may be useful for the treatment of hypertensive patients with or without vascular complications.

Effect of manidipine on balloon catheter-induced arterial smooth muscle cell proliferation in spontaneously diabetic GK rats.

The inhibitory effect of manidipine, a long acting calcium channel blocker, on vascular smooth muscle cell proliferation was investigated in spontaneously diabetic GK rats with balloon catheter-induced denudation of the carotid artery. Treatment with manidipine at doses of 4.6 and 15.1 mg/kg/day inhibited thickening of the neo-intima in the balloon catheter-injured artery without any effect on blood pressure and lowered the ratio of intima to wall areas and wall to total vascular areas in a dose-dependent fashion. These results suggest that manidipine inhibits an abnormal proliferation of the intima in the carotid artery of spontaneously diabetic rats.

Senescence-accelerated mouse (SAM): age-related reduced anxiety-like behavior in the SAM-P/8 strain.

Age-related behavioral changes in the passive avoidance, food neophobia, elevated plus-maze, and water-lick conflict tests were studied using substrains of senescence-accelerated mouse (SAM-P/8 and SAM-R/1) at 2 to 20 months of age. SAM-P/8 mice exhibited a significant impairment of acquisition of passive avoidance compared with SAM-R/1 mice when they were trained repeatedly, and the acquired response in SAM-P/8 mice rapidly diminished in contrast to good retention in SAM-R/1 mice. SAM-P/8 mice showed an age-related decrease in the latency to eat novel food after a 24-h food deprivation as compared with SAM-R/1 mice at 2 to 12 months of age, despite no significant difference in latency to eat familiar food between the two strains. In the elevated plus-maze test, SAM-P/8 mice had apparent increases in the number of entries into open arms and time spent on open arms in comparison to SAM-R/1 mice at 4 through 12 months of age; this difference became obvious with aging, implying age-associated reduced anxiety in the SAM-P/8 strain. In addition, SAM-P/8 mice exhibited a significant increase in punished water drinking compared to SAM-R/1 mice in the water-lick conflict test, although unpunished water intake in SAM-P/8 mice did not differ from that in the SAM-R/1 control. Aged SAM-R/1 mice, 20 months old, exhibited low anxiety-like behavior in the food neophobia and elevated plus-maze tests such as was seen in SAM-P/8 mice, when compared with young (4-month-old) SAM-R/1 mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Mesangial cell growth in genetically hypertensive rats and effect of calcium antagonists upon this growth.

Mesangial cells play an important role in physiological and pathophysiological regulation of glomerular functions. To explore the involvement of deranged mesangial cell functions in the pathogenesis of hypertension, the growth activity of mesangial cells was compared in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY). Upon exposure to fetal calf serum, the growth rate was significantly higher in mesangial cells cultured from glomeruli of 4-week old SHRSP than in those of age-matched WKY. This abnormally high growth of SHRSP mesangial cells was significantly inhibited by dihydropyridine calcium antagonists. Of the three antagonists tested, manidipine was the most potent inhibitor. Significant growth inhibition occurred at a concentration as low as 10(-12) M; inhibition as high as 65% was found at 10(-6) M. Calcium antagonists, particularly manidipine, may prevent or delay the development of hypertension not only through vasodilation but also through inhibition of mesangial cell growth. By slowing mesangial cell proliferation, calcium antagonists also may slow the progression of hypertension-induced glomerular sclerosis.

Hereditary transmission of tetralogy of Fallot, cardiac hypertrophy, and anomalies of great vessels in WKY/NCrj rats.

We examined 78 fetuses on d 21 of gestation (G21) and 83 neonates on d 2 after birth (A2), which were first generation offspring of WKY rats mated with normal Wistar rats (F1). In addition, we examined six groups of fetuses on d 19 of gestation (G19): 65 Wistar rats, 111 WKY rats, 85 F1, 100 F1 X F1, 92 F1 X Wistar, and 97 F1 X WKY progeny. In the F1 at G19, G21, and A2, there were abnormalities of the pulmonary valve, pulmonary outflow tract, architecture of muscle bundle, and pulmonary arterial branch, as well as hypoplastic ductus arteriosus and postnatal cardiac hypertrophy, similarly in males and females but at a lower incidence and to a lesser extent than in the WKY rats. Severe pulmonary valve dysplasia and ventricular septal defect with overriding of the aorta (tetralogy of Fallot), usually associated with a markedly small ductus, were not present or were very rare in the F1 and the F1 X Wistar but were present in the F1 X WKY and in the F1 X F1 less prevalently than in the WKY. The size of the ductus showed a continuous distribution in all of the six groups; there was a large skewing toward lower values in the WKY, the F1 X WKY, and the F1 X F1. These results suggest that cardiovascular anomalies of WKY rats are transmitted as autosomal recessive or incomplete autosomal dominant traits with an incomplete penetrance and variable expressivity or as polygenic traits. Chromosomal analysis of 31 WKY fetuses revealed no aberrations specifically related to the development of cardiovascular malformations.

A novel glutamate agonist, TAN-950 A, isolated from streptomycetes.

A novel antifungal amino acid antibiotic, TAN-950 A ([S]-2-amino-3-(2,5-dihydro-5-oxo-4-isoxazolyl)propanoic acid), was found to have affinity for three excitatory amino acid (EAA) receptors and to inhibit [3H]alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid ([3H]AMPA), [3H]kainate and [3H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid ([3H]CPP) binding competitively. It caused excitation of rat hippocampal CA1 neurons in vitro, an effect that was antagonized by an AMPA/kainate antagonist, 6,7-dinitroquinoxaline-2,3-dione (DNQX). Chemical modification of TAN-950 A brought about a large change in its pharmacological activity. Alkylation at the C-3 position of the isoxazolone ring markedly increased the ability to elicite neuronal firing. This agonistic effect was also antagonized by DNQX. The (R) enantiomer of TAN-950 A had increased selectivity for the N-methyl-D-aspartate (NMDA) receptor subtype. This selectivity was further enhanced by removal of the methylene group from the amino acid moiety. The most potent NMDA agonistic activity was observed with [R]-2-amino-2-(2,5-dihydro-3-methyl-5-oxo-4-isoxazolyl)acetic acid. These derivatives of TAN-950 A might be useful agents for investigating the pharmacological and physiological roles of EAA receptors.

Increase in basic fibroblast growth factor-like immunoreactivity in rat brain after forebrain ischemia.

Using immunohistochemical techniques, a study was conducted to determine whether basic fibroblast growth factor (bFGF) is generated as one of the 'self-repair' responses in rat brain following transient forebrain ischemia. In normal brain, slight bFGF-like immunoreactivity was observed. However, in rats exposed to 20 min of forebrain ischemia, intense bFGF-like immunoreactivity was observed in the CA1 subfield of the hippocampus and the caudate putamen, and marked activity was evident in the temporal cortex, corpus callosum and the CA4 subfield of the hippocampus. Marked neuronal degeneration was also observed in these brain regions following forebrain ischemia. These results suggest that induction of bFGF-like immunoreactivity may be related to the healing which follows brain ischemia.

Cholinergic drugs reverse AF64A-induced impairment of passive avoidance learning in rats.

The cholinergic neurotoxin AF64A was administered to rats in order to produce learning impairment to test the effect of cholinergic drugs. Seven days after receiving an intracerebroventricular injection of AF64A (2.5-7.5 nmol), rats were subjected to one-trial passive avoidance acquisition and tested 24 h later. Learning was significantly impaired at 3.75 nmol AF64A, a dose at which significant reduction in acetylcholine level and choline acetyltransferase and acetylcholinesterase activity in the hippocampus was observed but changes in monoamine levels in the hippocampus, general behavior, or sensory sensitivity were not observed. Arecoline (4 mg/kg, IP) and physostigmine (0.1 mg/kg, IP) significantly decreased the learning impairment produced by AF64A (3.75 nmol) when given before the acquisition of passive avoidance learning but not when given after the acquisition or before the 24 h retention test. These drugs and oxotremorine (0.1 mg/kg, IP) given immediately after the acquisition, however, improved passive avoidance retention when the interval between the acquisition and the test was shortened to 1 h. These results indicate that the impairment of learning in AF64A-treated rats is caused by a memory retention deficit and suggest that such impairment can be effectively ameliorated by cholinergic drugs.