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Biomedical subjects

A Takashima

Publications and source records attributed to A Takashima.

At least 199 records · Page 11Linked to original sources
PubMed1981

Application of high-performance liquid chromatography to the study of esterified 7-dehydrocholesterol in rat skin.

A novel and precise method for determining free and esterified 7-dehydrocholesterol in rat skin was developed by using a two-step high-performance liquid chromatography system. This method involves initial lipid extraction, separation of the free and esterified 7-dehydrocholesterol by, firstly, preparative high-performance liquid chromatography, saponification, and determination by, secondly, analytical high-performance liquid chromatography. This method was applied to the study of the 7-dehydrocholesterol in rat skin. Almost all of the 7-dehydrocholesterol in rat skin was present in an esterified form (78-93%). Ultraviolet exposure of the skin increased total 7-dehydrocholesterol content, however, the percentage of esterified 7-dehydrocholesterol was not altered appreciably. Application of this method to the study of the photo-metabolism of 7-dehydrocholesterol in rat skin revealed that almost all of the vitamin D3 produced by ultraviolet rays was in the esterified form.

Animals↗
PubMed1981

[Placental transfer and distribution of betamethasone 17,21-dipropionate in various regions of the brain of pregnant rats and mice (author's transl)].

As betamethasone 17,21-dipropionate induces adrenal atrophy in rat dams and adrenal hypertrophy in the fetus, we investigated the placental transfer of this compound using autoradiography and liquid scintillation counting in animals in the late stages of pregnancy. In these two species, 3H-betamethasone 17,21-dipropionate and/or its metabolites transferred across the placental barrier into fetal tissues and were distributed at levels lower than detected in the maternal tissues. The rat fetus showed a high uptake of radioactivity in the adrenal cortex. In pregnant rats, the ratios of the radioactivity in the adrenal cortex. In pregnant rats, the ratios of the radioactivity in brain tissues to the plasma in fetuses were much higher than in the dams after the administration of 3H-betamethasone 17,21-dipropionate or 3H-betamethasone. In the dams given 3H-betamethasone 17,21-dipropionate, the accumulation of radioactivity in the hypothalamus and septum was significantly greater than in other regions. The present study suggests that betamethasone 17,21-dipropionate or its metabolites transferred across the placental barrier following administration to the mother rat may produce an adrenal hypertrophy in the fetus and that accumulation of radioactivity in the hypothalamus of the dam may be related to a suppression of the function of hypothalamo-pituitary-adrenal axis.

Animals↗
PubMed1967

Serum and lymph lipids in rabbits with carbon tetrachloride-induced cirrhosis of the liver.

Lymph flow and the composition of lymph lipids from the hepatic and thoracic ducts of rabbits with cirrhosis of the liver (induced by 46-51 intramuscular injections of a mixture of carbon tetrachloride and olive oil at 4-day intervals) have been compared with those of control animals injected with olive oil only. In cirrhotic animals, the concentration of lymph lipids was not greatly altered, but lymph flow, and consequently the hourly transport of lipids by lymph were greatly increased; the increase in transport of cholesteryl esters, free cholesterol, and phospholipids by way of the thoracic and hepatic duct lymph was particularly striking. The concentration of these lipid fractions in serum from the cirrhotic rabbits was also increased. The differences normally observed between lipid fatty acid compositions of serum and lymph disappeared in cirrhotic animals; this is interpreted as due to increased hepatic permeability to lipoproteins.

Journal Article↗
PubMedDate not supplied

Effect of vasoactive intestinal peptide on dopaminergic system in the rat brain.

The present study analyzed the effect of vasoactive intestinal peptide (VIP) on the content of dopamine (DA) and its main metabolite, DOPAC, in the rat brain. Intracerebroventricular administration of VIP increased the DA and DOPAC content, causing a dose-dependent increase in the DOPAC/DA ratio in various regions of the brain. The results suggest that VIP facilitates the DA metabolism in the brain.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Memory effect of caerulein and its analogs in active and passive avoidance responses in the rat.

The memory effects of caerulein (CER) and its analogs ([des-Gln2]-CER and [Leu5,Nle8]-CER) were compared with that of cholecystokinin octapeptide (CCK-8) using active and passive avoidance responses in rats. In the active avoidance test, single subcutaneous (SC) injection of CER and its analogs immediately after the learning trials at doses of 10 and 100 ng/kg prevented extinction of learned task for 10 days, and at a dose of 1000 ng/kg for at least 15 days, but the effect of CCK-8 was somewhat weaker. In the saline control group, the number of responses decreased after 5 days. In the passive avoidance response, electroconvulsive shock (ECS)-induced amnesia was partially prevented by CCK-8 at doses of 100 and 1000 ng/kg SC, while CER and its analogs at doses of more than 100 ng/kg totally prevented the ECS-induced amnesia. Intraperitoneal administration of scopolamine caused complete amnesia which was also partially prevented by CCK-8, while CER could totally prevent the amnesia following SC injection of 2 micrograms/kg. These results indicate that CER and its analogs are more effective than CCK-8 for preventing experimental amnesia.

Amino Acid Sequence↗
PubMedDate not supplied

Effect of caerulein on decreased latency of passive avoidance response in rats treated with NMDA receptor antagonists.

The effect of subcutaneous injection of caerulein on memory impairment induced by intracerebroventricular administration of NMDA receptor antagonists was examined in the passive avoidance response of the rat. When rats were treated with AP5, AP7, CPP or MK-801, the retention latencies decreased markedly. However, in rats that received caerulein immediately after the training trials, the latency increased to some extent. Pretreatment with caerulein and subsequent injection of the competitive NMDA receptor antagonists AP5, AP7 and CPP caused a more apparent increase in the latency. The noncompetitive NMDA receptor antagonist MK-801 was not affected by pretreatment with caerulein. The difference might be, at least in part, due to the sites of action of these NMDA receptor antagonists.

2-Amino-5-phosphonovalerate↗
PubMedDate not supplied

Pretreatment with caerulein protects against memory impairment induced by protein kinase C inhibitors in the rat.

The effect of subcutaneously injected caerulein (CER) on memory impairment induced by protein kinase C (PKC) inhibitors, H-7 and melittin, was examined in rats. Intracerebroventricular injection of PKC inhibitors caused marked memory impairment in one-trial passive avoidance response and Morris water tank tasks. However, when rats were pretreated with CER at a subcutaneous dose of 1 microgram/kg 3 hours before the training trials, the reduced latency of the passive avoidance response was significantly increased, and in the Morris water pool tasks the memory deficit induced by PKC inhibitors completely disappeared. These results indicate that CER can offer protection against the effect of PKC inhibitors at least from the viewpoint of the memory processes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMedDate not supplied

Protective effect of cerulein on memory impairment induced by protein synthesis inhibitors in rats.

Previous studies have demonstrated that NMDA receptor antagonists and protein kinase C inhibitors induced marked memory impairment in rats, but that peripherally administered cerulein (CER) prevented these effects. In the present study, the effect of subcutaneously administered CER on amnesia induced by protein synthesis inhibitors was examined in passive and active avoidance responses and in the Morris water maze test. Intraperitoneal injection of the inhibitors produced marked memory impairment, but the effect was abolished by combined administration with CER. The effective dose of subcutaneously injected CER was, on a molar basis, three thousand- and six thousandfold less than the dose of anisomycin, and two hundred eighty- and three thousandfold less than the dose of puromycin in the passive and active avoidance response experiments, respectively. Similarly, in the Morris water maze test, behavioral disturbances produced by the protein synthesis inhibitors were abolished by CER. These results indicate the effectiveness of CER in preventing memory impairment induced by protein synthesis inhibitors.

Amnesia↗