Effects of intraventricular administration of insulin on thyrotropin secretion in rats

Summary Intraventricular administration of insulin stimulates increases in the levels of thyrotropin-releasing hormone and thyrotropin in rats.Ovine insulin was kindly supplied from Shimizu Pharm. Co., Ltd. (Japan).Rat TSH radioimmunoassay kit was kindly supplied by NIAMDD.     

In vivo lipolytic action of glucagon in brown adipose tissue of warm-acclimatized and cold-acclimatized rats

Summary Glucagon infusion caused a marked increase of brown fat venous FFA concentration, but the extent of increase was less in cold-acclimatized rats than in warm-acclimatized ones. Systemic venous FFA was not appreciably influenced by glucagon. Propanolol did not modify the changes induced by glucagon.The authors wish to thank the Novo Industri A/S for the gift of glucagon. — Address of Tomie Ohno: College of School Health, Hokkaido University of Education, Asahikawa 070 (Japan).     

Antidiuretic activities of substance P and its analogs

Summary Substance P (SP) and analogs, including 5 nucleoside (ARA or HRA)-peptides, were examined for antidiuretic activity in ethanolized rats. The activity was potent in the analogs embodying the C-terminal hexapeptide, weak in the nucleoside-pentapeptide, and negligible in the nucleoside-tetrapeptide. In addition, the activity was increased by acylation of the hexapeptide. The antidiuretic potencies were also compared with the hypotensive potencies.This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan, and by a grant from the Imanaga Foundation, Nagoya, Japan.     

Inhibition of neurotensin (NT)-induced glucagon release by [D-Trp11]-NT1

Summary A synthetic analog of neurotensin (NT), [D-Trp¹¹]-NT, antagonized NT-induced hyperglucagonemia and hyperglycemia, and also NT-induced glucagon release from pancreatic islets in rats.This work was supported in part by a grant from the Imanaga Medical Research Foundation, Nagoya, Japan. Address for reprint requests: M.U., Department of Surgery, National Nagoya Railway Hospital, Taiko 1-chome, Nakamura-ku, Nagoya 453, Japan.     

Ultrastructural observation on the tips of growing vascular cords in the rat cerebral cortex

Summary The distal ends of the vascular cord in the cerebral cortex are investigated electron microscopically in rats at the 13th postnatal day. The tip of the vascular cord consists of central cuboidal cells (primitive endothelial cells) and surrounding flat cells (primitive pericytes), and has no lumen. The primitive endothelial cells (tip cells) possess several long tentacles which contain only fibrous structures and extend through the neuropile.This study was supported in part by a grant in aid for Scientific Research from the Ministry of Education of Japan (No. 448085).     

Regression of granular pericytes in cerebral fine vessels of rats after administration of a vitamin E deficient diet

Summary Prolonged administration of a vitamin E deficient die to Wistar rats resulted in regressive changes in granular pericytes distributed around fine vessels of the cerebral cortex. The regressive signs included expansion of endoplasmic reticula, swelling of mitochondria and increase of vesicular structures. Rupture of the limiting membranes of the intracellular granules often accompanied these changes. The finding seems important for an understanding of the physiology and nutriology of granular pericytes in the brain.This study was supported in part by a grant in aid for Scientific Research from the Ministry of Education of Japan (No. 448085).     

Evidence for no relationship of the pineal activity with the neonatal shrinkage of Leydig cells in the rat

Summary The collective volume of Leydig cells in prenatally pinealectomized newborn rats declined as sharply as in intact newborn rats. Also, the collective volume in pups born in the dark declined in a fashion similar to that in pups born in the light. The results indicate that neither the pineal gland nor the light is responsible for the neonatal shrinkage of Leydig cells.This study was supported in part by a Grant-in Aid for Scientific Research (No. 548067) from the Ministry of Education, Science and Culture of Japan.     

Effects of various hormones and adrenalectomy on the levels of amylase in rat pancreas and parotid gland

Summary Dexamethasone, adrenocorticotropic hormone and thyroxine increased the amylase activities in both the pancreas and the parotid gland of infant rats. After adrenalectomy, the amylase activities of the pancreas and parotid gland were about half the control levels, suggesting that both glucocorticoid and thyroxine are involved in maintaining the amylase activities in these organs.Acknowledgments. This work was supported by Grants-in-Aid for Cancer Research from the Ministry of Education, Science and culture, Japan, and the Ministry of Health and Welfare, Japan.     

Inhibition of testicular androgenesis by urinary gonadotropin-inhibiting substances in rats

Summary The effect of urinary gonadotropin-inhibiting substances (GIS) on the androgen synthesis in rat testes was studied in vitro and in vivo. GIS, which was added to the incubation medium containing teased testicular tissues and injected into rats for 2 days, showed a suppressive effect on the formation of androstenedione from pregnenolone in the testis.Supported by a Scientific Research Grant from the Ministry of Education of Japan.     

Effects of 2-deoxy-D-glucose,glucose and insulin on efferent activity in gastric vagus nerve

Summary Intracarotid injection of 2-deoxy-D-glucose and insulin increased the efferent activity in the gastric vagus nerve of anesthetized rats, while glucose injection transiently decreased vagus activity.This work was supported by research grant No. 212105 from The Ministry of Education, Science and Culture of Japan.     

Expression of the mutant gene for L-gulono-γ-lactone oxidase in scurvy-prone rats

A mutant strain of Wistar rats with L-gulono--lactone oxidase deficiency has recently been established. To investigate this deficiency by DNA and RNA blot hybridization analyses, a fragment of a previously cloned cDNA encoding rat L-gulono--lactone oxidase was used as a probe. When genomic DNA of the mutant rat was digested with several restriction enzymes, the probe hybridized to fragments of the same sizes as those produced from DNA of normal rats. Poly(A)⁺RNA from the liver of the mutant rat was found to contain an L-gulono--lactone oxidase-specific mRNA of a normal size at a comparable level to that of normal rats. An in vitro translation experiment revealed that the mRNA programmed the synthesis of an enzyme protein which had the same molecular weight as that of the translational product of the normal mRNA, although the amount synthesized was markedly reduced as compared with that synthesized with the normal mRNA. In accordance with this observation, a very low but definite degree of L-gulono--lactone oxidase activity was detected in the microsomes of the mutant rat by a newly developed, highly sensitive method.Acknowledgments. The authors thank Dr Susumu Makino, Shionogi Research Laboratories, Shionogi & Co., Ltd, Japan, for his kind donation of normal (ODS- +/+) and ODS (ODS-od/od) rats. This work was supported in part by Grant-in-Aid (59570103) for Scientific Research from the Ministry of Education, Science and Culture of Japan.     

Carnosine-like immunoreactivity in the primary olfactory neuron of the rat

Summary Using the peroxidase-antiperoxidase immunohistochemical technique, carnosine-like immunoreactivity was demonstrated to localize specifically within the primary olfactory neuron.This study was supported by grants from the Ministry of Education, Science and Culture, Japan (No. 61218016). Reprint requests to I. N., Department of Anatomy, School of Medicine, Fujita-Gakuen Health University, Toyoake, Aichi 470-11, Japan.     

Uptake of fat by fluorescent granular perithelial cells in cerebral cortex after administration of fat rich chow

Summary As reported previously, fluorescent granular perithelial cells (F.G.P.) are distributed along small blood vessels, possibly postcapillary venous vessels, in the cerebral cortex; these cells take up intraventricularly administered horseradish peroxidase efficiently. In this study it is shown that lipid substances of the blood are easily incorporated into F.G.P. and stored in their cytoplasm. The quantity of fat deposits in F.G.P. varies with the age of the animal and is very marked in old rats. The administration of elastase suppresses the fat uptake and/or facilitates the fat metabolism in F.G.P.Acknowledgment. This study was supported in part by a grant in aid for Scientific Research from the Ministry of Education of Japan (No. 448085). The authors also would like to express their hearty thanks to Eisai Co. for a supply of elastase.     

Cytoarchitecture of monoamine-containing cells in the frog's gustatory epithelium

Summary With the availability of 5,6-dihydroxytryptamine, the overall morphology and the characteristics distribution of monoamine-containing cells in the frog's gustatory epithelium came to be clearly elucidated by fluorescence histochemistry.This work was supported by a grant from the Ministry of Education in Japan, No. 177015.The authors gratefully acknowledge the support and helpful advice of Dr T. Kanaseki, Professor of Anatomy, Faculty of Medicine, Kyushu University, Fukuoka 812 (Japan).     

T-cell leukemia induced by 1-propyl-1-nitrosourea in Fischer rats

Summary T-cell leukemia was induced at a high rate in female Fischer rats by continuous oral administration of 1-propyl-1-nitrosourea. No association of oncorna viruses were found in the leukemogenesis.The authors are greatly indebted to Professor K. Yokoro of the Department of Pathology, Research Institute for Nuclear Medicine & Biology, for his valuable suggestions. This work was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan.     

New inversion of the pair no. 3 chromosome in a black rat

Summary A Japanese black rat (Rattus rattus tanezumi) with a subtelocentric pair no. 3 chromosome was found in Gotenba, Japan. By comparison of the length in both members of the chromosome pair, and from the G-ban pattern, the subtelocentrics seemed to have developed from the original acrocentrics by the pericentric inversion.The author wishes to express his sincere thanks to Dr. K. Moriwaki for the help of the collection of the material and also for the skilful technical help of Miss Y. Ochiai. Supported by a grant-in-aid from the Ministry of Education, Science and Culture of Japan (Nos 111510 and 111506). Contribution No. 1125 from the National Institute of Genetics, Japan.     

Plasma triiodothyronine,thyroxine and thyrotrophin levels in germfree rats

Summary Plasma T₃, T₄ and TSH levels in developing germfree rats were high, low and normal as compared with those in conventional counterparts. The high T₃/T₄ ratio in germfree rat plasma was lowered by cholestyramine feeding.This work was supported in part by a grant from the Imanaga Foundation, Nagoya, Japan.     

Renal effects of the inhibitor of thromboxane A2-synthetase OKY-046

Summary Acute renal failure (ARF) was associated with increased urinary thromboxane (TXA₂) excretion and lessened excretion of sodium (U_NaV) and fractional excretion of sodium (FE_Na%). The inhibitor of thromboxane A₂-synthetase OKY-046 enhanced sodium excretion and fractional excretion of sodium in normal and saline loaded animals whereas it partially prevented the reduction in sodium excretion and creatinine clearance and significantly increased fractional excretion of sodium in glycerol treated rats suggesting a partial protection against the development of acute renal failure.Acknowledgment. This work was supported by the Public Benefit Foundation Alexander S. Onassis (G-73). We thank ONO Pharmaceutical Co. Ltd, Kissei Pharmaceutical Co. Ltd, Osaka, Japan, and Dr A Hornych for their generous donations of OKY-046 and anti6keto-PGF_1a antibodies respectively.     

Effect of pulsing electromagnetic fields on DNA synthesis in mammalian cells in culture

Summary DNA synthesis in Chinese hamster V79 cells was significantly enhanced when they were exposed to weak, pulsing electromagnetic fields generated by specific combinations of the pulse width (25s), frequency (10, 100 Hz) and magnetic intensity (2×10^–5 8×10^–5T). Conversely the DNA synthesis of cells in the fields at 4×10^–4 T was repressed to 80% of that in controls not exposed to the fields.This work was supported by Kaken Pharmaceutical Co., Ltd, Tokyo, Japan, and in part by a Grant-in-Aid from the Ministry of Education, Science and Culture of Japan and from the Foundation for Life Science Promotion Tokyo, Japan to I.K.     

Development of the hypothalamic-hypophysial-gonadotrophic activities in fetal rats

Summary Pituitary responsiveness to LHRH and anti-LHRH serum was investigated in fetal rats aged 18.5–22.5 days. Synthetic LHRH injection in utero into fetuses brought about a remarkable depletion of pituitary-LH with a corresponding increase of serum-LH on day 18.5. On the contrary, anti-LHRH serum administration to day-20.5 fetuses caused a significant augmentation of pituitary-LH 1 day later. These data indicate that LH-gonadotrophs respond to LHRH even on day 18.5, and that endogenous LHRH begins to affect LH-gonadotrophs on day 20.5.This work was supported by a grant from Ministry of Education, Science and Culture, Japan. The exert technical assistance of Mr Yoshihito Okamura is gratefully acknowledged.