Protective effect of arginine, leucine and preinjection of insulin on glutamate neurotoxicity in mice

The simultaneous intubation of 10-day-old mice with either 2.28 g/kg body weight arginine hydrochloride or 0.2 g/kg b.wt. leucine significantly reduced the number of necrotic neurons in the arcuate nucleus (AN) of the hypothalamus resulting from 2 g/kg b. wt. monosodium L-gultamate (MSG). The prior injection of 0.02 units per capita of insulin suppressed the MSG-induced lesions to an even great extent. These findings are believed to form a basis for the ineffectiveness of dietary MSG in producing hypothalamic lesions.

Studies on brain lesion by administration of monosodium L-glutamate to mice. I. Brain lesions in infant mice caused by administration of monosodium L-glutamate

Light-microscopic examination was performed on the brain lesions induced by monosodium L-glutamate (MSG) in neonatal and infant mice of ICR strain. Lesions characterized as cytoplasmic balooning, chromatin clumping, pyknosis and karyorrhexis of neurons were recognized in the arcuate nucleus (AN), subfornical organ, preoptic area, area postrema and cerebral cortex. The most vulnerable region was the AN in which the region near the root of the median eminence was easily damaged. The changes in the AN were severest in 7-day-old mice, but only slight in 20-day-old mice. Thresholds of inducing AN lesions in 10-day-old mice after intraperitoneal injection and force-tube feeding were 0.4 and 0.7-0.8 g/kg body weight, respectively. The threshold of retinal changes was about 2.5-fold that of AN in force-tube feeding. In neonatal mice injected daily with 4 g MSG/kg body weight, the neurons of the AN disappeared almost completely by the 4th day of intraperitoneal administration.

Studies on brain lesions after administration of monosodium L-glutamate to mice. II. Absence of brain damage following administration of monosodium L-glutamate in the diet

The effects of monosodium L-glutamate (MSG) on the brain of mice were examined by light-microscopy under the intended conditions of use of this material. Basal diet containing 5, 10 or 15% w/w MSG was fed to pregnant, lactating and weanling mice ad libitum, resulting in the ingestion of 14.0, 42.8 or 42.0 g/kg body wt. of MSG a day respectively. Mice at the same developmental stages were given the basal diet and 5% w/w MST in aqueous solution ad libitum, the maximum ingestion of MSG being 16.9, 31.4 and 26.8 g/kg body wt. a day respectively. Light-microscopy examination revealed no pathological changes in the hypothalamic arcuate nuclei (AN) of all treated mice, i.e., pregnant females and their fetuses, lactating females and their sucklings, and weanlin mice. Pregnant females and their fetuses, and weanling mice, injected subcutaneously with either 5.0 or 4.0 g/kg body wt. of MSG, showed "Glu-type lesions" in the hypothalamus.

Contact angle and surface tension in studies of lung surfactant

The contact angle (theta) was determined in combination with surface tension measured in a Langmuiur-Willhelmy surface tension balance. Correction of the surface tension by the contact angle factor (1/cos theta) was tried on the monolayer curve of dipalmitoyl phosphatidyl choline (DPPC) and total lipid extracts from the bovine lung surfactant material (TLE). The contact angle was observed with an optical apparatus called a Contangulometer and pictures taken discontinuously, and was determined by drawing tangents at the peak of a junction between the water mensicus and a glass plate. The contact angle was about 15 degrees, and had a narrow range of variation until the surface tension became very low, less than 5 dynes/cm, and then the contact angle jumped to almost 90 degrees both in DPPC and in TLE. It is concluded that the directly recorded surface tension curve underestimates the value by about 3-4% and that when the surface tension becomes very low, less than 5 dynes/cm, the value is no longer valid because the contact angle becomes nearly 90 degrees.

Possible sequential transformation of a series of acidophils in the pituitary autografts in the renal capsule of male rats in association with ACTH cell

In our electron microscopy, acidiphils in the pituitary autografts placed in the renal capsules of immature male rats underwent a sequential transformation with the lapse of time: Within 3 and 6 days, all the somaotrophs packed with the large granules of about 350 mmu diameter dispersed. The size and number of the granules in somatotrophs were quickly and markedly reduced with severe modification of cell shape. There was evidence during this time course that Siperstein's or Moriarty's corticotrophs might be synonymous with the stellate shape of acidophils with the arrangement of small granules 150-200 mmu in diameter along the cell acidophils. The "acidophils of the small granule type" possibly related to ACTH production according to Yoshimura et al. (1974) were frequently detected in the grafts as elongated or irregularly shaped cells. Their minute granules 100-150 mmu in diameter were also distributed in row in the cytoplasmic peripheral area. Gradual loss of the minute granules below 100 mmu in diameter eventually made the acidophils to transform into agranular cells. Our own idea that ACTH secretion might correlate with a series of cells transforming along the acidophil-axis was indirectly supported by the present observation on pituitary grafts. On the other hand, basophils rapidly degenerated and died away. Ten and 20 days after autografting, the graft cells which might be principally composed of the cells of acidophil origin enormously proliferated through mitotic division, showing the homologous fine structure, without the normal cell individuality. They always contained three different size and shape of granules simulataneously. Significance of such a rapid and strong response of acidophils to the ectopic replacement in the immature male rats was discussed from the view-point of hypothalamic regulation to simple protein hormones.

Origin of prolactin cells in the pituitary autografts in the renal capsule of young male and female rats

Origin of the prolactin cells in the pituitary grafts autotransplanted into the renal capsule was electron microscopically investigated in young male and female rats. Prolactin cells may mainly originate from the completely degranulated acidophils after grafting in both sexes. The comprehensive degranulation of acidophils may be essential condition for the development of prolactin cells. Formation of initial prolactin granules is related to the Golgi apparatus in 3 and 6 days in the males. Even prolonged transplantation for the duration of 10 and 20 days failed to develop the typical prolactin cells storing large polymorphic granules in the grafts in the males. In the females, however, the population of prolactin cells became higher (20-30%) and their granulation was more rapidly advanced than in the male. Nine and 16 days after grafting quite numerous typical prolactin cells, characterized by the pronounced vesiculation of ER stored large polymorphic granules in the females. Progressive vesiculation of ER in degranulated acidophils may be the second necessary condition for establishing the prolactin cells. Thus, the entire course of cell conversion of acidophils into prolactin cells was observed in this study. All the graft cells including prolactin cells finally turned into the cells losing the respective individuality (10 days in the males; 32 days in the females). This fine structural similarity was striking in the males. We could not, however, deny the possibility of origination of prolactin cells from the follicular cells or their adjoining undifferentiated cells.