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Volume 106, Issue 2
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Koichi ISHIKAWA1995 Volume 106 Issue 2 Pages 67-76
Published: 1995
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSDiscoveries of long-term potentiation and immediate early gene in the central nervous system have enabled new developments in experiments on learning and memory. These experiments are conducted in many kinds of animals with different procedures, physiology, chemistry and pharmacology. However, there is still some confusion when these various procedures are discussed. Memory is defined as information storage of an animal's previous experiences. The memory induces changes in behavioral performance. This means that memory must be observed in whole animals, and one question that can occur is how does long-term potentiation, for example, correlate with memory. Furthermore, memory has been divided into two major classifications, declarative and non-declarative, from the comparison of amnesias observed in humans and animals. The declarative memory can be observed in human subjects, but not in animals. This article presents a neuronal circuit concerning memory formation and some results obtained from benzodiazepines, and it discusses some problems encountered executing when experiments on learning and memory. In addition, the discussion speculates over the possibility for an “antidementia drug”.View full abstractDownload PDF (8757K) -
Yoshikatsu MASUDA, Shigeo MURAI1995 Volume 106 Issue 2 Pages 77-84
Published: 1995
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSThis report deals with three different maze methods using spontaneous learning behavior. Fortyeight mice housed in an apparatus with a multiple maze mastered the maze task on the 5th day after the start of housing. Then they were divided into four groups, and two of the groups were treated with AF64A (3.5 nmol, i.c.v.) or trimethyltin (TMT, 3 mg/kg, p.o.), and the other two groups were treated with the vehicle as the respective control. Seven days after the treatment, their memory retrieval was tested. Subsequently, the same mice were housed in the apparatus with a T-maze. After the finish of the experiment using the T-maze, they were housed in the apparatus with an eight arm radial maze. The control groups mastered the T-maze task with a 3-sec delay on the 4th day after the start of housing and the radial maze task on the 10th day after the start of housing. Both the treatments lowered the performance in all maze tasks. These results show that the mice housed in the apparatus with maze learned to negotiate the maze spontaneously, and the apparatuses are useful for estimating memory in mice with little effort.View full abstractDownload PDF (6014K) -
Masatoyo KAGOSHIMA, Yukari TSUBATA, Hideyo SHIMADA1995 Volume 106 Issue 2 Pages 85-97
Published: 1995
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSWe attempted to make a basic model to investigate a series of factors that induce histological changes in systemic hypoxia-reoxygenation injuries. At first, we set the experimental conditions for hypoxia and the hypoxia-reoxygenation models as follows: respiration volume: 1.5 ml/stroke, respiratory frequency: 80 times/min, oxygen concentration: 14%. Next, Male SPF Wistar rats were anesthetized with pentobarbital sodium. For artificial ventilation, a cannula was inserted in the trachea and connected to the rodent ventilator through two flow meters to allow mixing of 100%N2 and 95%O2-5%CO2 gases at a desired ratio. The influence of hypoxia-reoxygenation was studied and evaluated histologically and biochemically. The rats were placed under the hypoxic condition for either 3 or 6 hr. Then, oxygen partial pressure was restored to 21% followed by reoxygenation for either 3 or 6 hr. Then the rats were sacrificed, and the pituitary, adrenals, heart, stomach and kidneys were removed. The results were as follows: 1) GPT activities were increased by a load of hypoxia, but no influence of reoxygenation was detected. 2) Under the condition of experimental hypoxia, the weights of the pituitary and adrenals increased significantly. 3) The histological findings indicated that 6-hr hypoxia followed by 3-hr reoxygenation induced hypoxia-reoxygenation injuries mostly affecting the anterior pituitary and adrenal medulla.View full abstractDownload PDF (11188K) -
Yoshinori IWAHISA, Yukihiro YASUNAGA, Hiroshi OCHI, Mamoru MATSUURA, T ...1995 Volume 106 Issue 2 Pages 99-111
Published: 1995
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSThe analgesic and anti-inflammatory activities of Y-23023, a new nonsteroidal analgesic and antiinflammatory compound, were investigated in acute, subacute and chronic pain models in rats. In the carrageenin paw edema test, Y-23023 (0.3 ?? 3 mg/kg, p.o.) dose-dependently inhibited hyperalgesia assessed by the Randall-Selitto method and paw edema. Y-23023 (1 mg/kg, p.o.), when administered at 2 hr after carrageenin injection, significantly elevated the reduced pain threshold without affecting paw edema. Therefore, the antinociception activity induced by Y23023 was not the result of its anti-inflammatory activity. In addition, Y-23023-induced antinociception was resistant to post-treatment with naloxone (2 mg/kg, s.c.), but was antagonized by intraplantar injection of prostaglandin E2 (1 μg/paw). These results suggest that Y-23023 produces a peripheral analgesic effect mediated by inhibition of prostaglandin production. Y-23023 (0.3 ?? 10 mg/kg, p.o.) also had a potent inhibitory effect on the silver nitrate-induced arthritic pain. In supressing acute and subacute pain, Y-23023 was more potent than diclofenac sodium, indomethacin and loxoprofen sodium. The analgesic and anti-inflammatory activities of Y23023 (0.1 ?? 1 mg/kg/day, p.o.) on the adjuvant-induced hyperalgesia and the paw swelling were nearly equipotent to diclofenac sodium and indomethacin, but were more potent than loxoprofen sodium. Therefore, Y-23023 would be regarded to show predominantly strong analgesic activity in acute and subacute pain when compared with reference drugs. The above results suggest that Y-23023 is a novel analgesic compound with an anti-inflammatory activity in the clinical field.View full abstractDownload PDF (9009K) -
Hiroshi YOSHIMOTO, Nobuo NAGANO, Tsuyoshi NISHITOBA, Hiromitsu SATO, S ...1995 Volume 106 Issue 2 Pages 113-122
Published: 1995
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSThe effects of chitosan-coated dialdehyde cellulose (chitosan DAC), a newly developed oral adsorbent of urea and ammonia, were examined in an in vitro adsorption study and in normal rats. Chitosan DAC showed high adsorption capacity for urea and ammonia in an in vitro study using the diluted supernatant of rat gastrointestinal fluid. In contrast, Kremezin, an oral charcoal adsorbent (AST-120), had little influence on these substances. In normal rats fed diets containing chitosan DAC (1, 2, 3, 4, 5, 7, and 10% content) for three weeks, increases in fecal wet weight, fecal dry weight and fecal water content were observed in a dose-dependent manner. In addition, chitosan DAC feeding increased fecal excretion of nitrogen and electrolytes (sodium, potassium and chloride ions) and decreased the apparent protein ratio in a dose-dependent manner. There were no obvious effects in serum parameters except that increased levels of protein and albumin and decreased levels of blood urea nitrogen, cholesterol and glucose were observed in rats fed a high concentration of chitosan DAC. In conclusion, these findings suggest the possibility that chitosan DAC treatment might be effective for improving chronic renal failure.View full abstractDownload PDF (7468K) -
Nobuo NAGANO, Hiroshi YOSHIMOTO, Tsuyoshi NISHITOBA, Hiromitsu SATO, S ...1995 Volume 106 Issue 2 Pages 123-133
Published: 1995
Released on J-STAGE: February 06, 2007
JOURNAL FREE ACCESSThe effects of chitosan-coated dialdehyde cellulose (Chitosan DAC), a newly developed oral adsorbent of urea and ammonia, were examined in rats with progressive chronic renal failure (CRF) induced by adriamycin. CRF rats induced by repeated injections of adriamycin were fed a diet containing chitosan DAC (5% content) or Kremezin (5% content), an oral charcoal adsorbent (AST-120) under strict paired-feeding for four months. CRF rats that received both a normal diet and Kremezin showed progressive azotemia, hyperphosphatemia, hyperlipidemia, proteinuria, and anemia, and began to die from 9 weeks after feeding started. In contrast, chitosan DACtreatment showed marked prolongation of the survival period and decreases in blood urea nitrogen, serum creatinine, and serum phosphate. In addition, chitosan DAC-treatment ameliorated anemia in CRF rats, although hyperlipidemia and proteinuria were not improved. Furthermore, fecal weight, fecal water content, fecal nitrogen and fecal sodium were markedly increased, and the apparent protein ratio was decreased in CRF rats fed a diet containing chitosan DAC for 9 weeks. In contrast, none of these effects were observed in CRF rats receiving Kremezin. These observations suggest the further possibility of using oral adsorbent therapy for CRF patients.View full abstractDownload PDF (7951K)
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