Strain differences of hypertension induced by dietary NG-nitro-L-arginine in normotensive rats.

When the potent inhibitor of nitric oxide (NO) synthesis NG-nitro-L-arginine (L-NNA) was incorporated into the diet, hypertension was induced and sustained due to the effects of the long-term inhibition of endothelium-dependent relaxing factor (EDRF)/NO. The effects of L-NNA on normotensive rats of four strains (Donryu, Sprague-Dawley (SD), Wistar, and Wistar-Kyoto (WKY)) were compared relative to control rats. L-NNA administration caused a sharp initial increase in systolic blood pressure (SBP) at 2 weeks in all animals, and this was followed by a gradual and steady increase until 4 weeks. At the end of the experiments (5 weeks), the mean SBP of Donryu and SD rats was decreased. The maximum blood pressure of Donryu and Wistar rats during the experiments exceeded 200 mmHg, but that of SD and WKY rats was below 200 mmHg. Body weight loss and death were observed only in L-NNA-fed Donryu rats. Pathological changes in the kidneys and the morbidity rates for the lesions were determined, and indicated that the Donryu L-NNA group was 100% positive. These results suggest that the Donryu strain is more sensitive to L-NNA than the other strains. That dietary L-NNA-induced hypertension in normotensive rats of the four strains provides a new artificially-induced hypertensive model in which vasoconstriction occurs mainly due to EDRF deficiency.

[Morphological studies on preputial gland of mice--1. Light and transmission electron microscopic observations of preputial gland in male mice].

Male BALB/c mice isolated after weaning were housed two mice per cage at the age of 10 weeks. After 1 week, each pair of mice was observed for social dominance, and compared with control mice kept in isolation. The preputial gland in the socially dominant animal was histologically examined. The preputial gland consisted of a congregation of branched simple tubuloacinar gland and typical holocrine secretion on morphological examination. Acinar cells in the dominant animals were large, multiplicative and hypertrophic compared with those of controls and subordinates. Dominant animals required copious secretion for attainment and maintenance of a dominant social position. Acinar cells of subordinates were very small, flattened and atrophied because fatty secretion particles filled the luminal duct. These accumulated secretion particles pressed the acinar cells and caused degeneration. Not only luminal acinar cells but also central acinar cells and some basal acinar cells were degenerated. Electron micrographs showed that basal acinar cells in dominant animals contained many mitochondria, agranular endoplasmic reticulum and free ribosomes in the cytoplasm, whereas those of subordinates contained myelin bodies and lipid droplets. Therefore, it is suggested that the synthesis of secretion particles in acinar cells of subordinates hardly occurred.

[Behavioral characteristics of open-field activities in NOD mice].

The open-field test was carried out on NOD mice of both sexes between the ages of 40 to 300 days. The behavior of both sexes of mouse was observed for 3-minute periods with an interval of 20 days. The mean scores of ambulation and rearing increased at the ages of 40-80 days old, and both scores decreased more than 100 days old. The onset of overt diabetes (DM) in female mice were observed after 120 days old. After the onset of DM with great loss of body weight, the scores of ambulation and rearing were dramatically decreased. Other parameters, urination, defecation, and preening were not changed with age of both sexes. These data suggest that conspicuous weight loss with the expression of overt diabetes in NOD female mouse might correlate to decrease of the ambulation and rearing scores.

[Effects of sex hormone on the dilatation of urinary tubule and acidophil body in NON mice].

The influences of sex hormones on the dilatation of the urinary tubules and acidophil bodies were histologically investigated in NON (Non-Obese Non-diabetic) mice. Although the dilatation of the proximal tubules and acidophil bodies in NON mice were observed only in female but not in male, a slight dilatation and a few bodies were also observed in castrated male NON mice. Moreover, in ovariectomized female NON mice the dilatation and bodies were less compared with intact female NON mice. Estradiol administration induced prominent dilatation and numerous acidophil bodies, while the administration of testosterone showed a complete preventive effect. Therefore, it is suggested that the dilatation of the tubules and the acidophil bodies can be profoundly influenced by sex hormones.

Effects of mandibular gland ectomy and environmental temperature of dams on eyelid opening and body weight of pups in mice.

Effects of the mandibular gland ectomy and environmental temperature to pups in Jcl: ICR mice were studied. In normal environmental animal room (A room; Tem. 23 +/- 2 degrees C, R. H. 50 +/- 10%), the mammary gland weights of lactating mothers and the body weights of pups in sialoadenectomized groups were slightly smaller than that of control groups during lactating period, whereas the eyelid opening of pups was not different between both groups and all pups exhibited complete eyelid opening on 14th day after birth. On the other hand, in cold environmental animal room (B room; Tem. 15 +/- 2 degrees C, R. H. 60 +/- 20%), the mammary gland weights of lactating mothers and the body weights of pups in sialoadenectomized groups were smaller than that of sialoadenectomized groups in A room and the eyelid opening of pups was considerably delayed when compared with that of control groups. The pups exhibited complete eyelid opening at 16th day after birth. These results were caused by mandibular gland ectomy and considered to be easily influenced by environmental conditions.

[Cell infiltration in various organ and dilatation of the urinary tubule in NON mice].

The non-obese non-diabetic (NON) mouse, which shows no glycosuria, is a subline of the non-obese diabetic (NOD) mouse. Cellular infiltrations in various organs were observed by light and electron microscopy in both sexes from 30 to 300 days after birth. These infiltrations were found in the kidney, pancreas, mandibular gland, parotid gland, exorbital lacrimal gland, and thyroid gland, but not in the adrenal gland, sublingual gland, testis and ovary. The infiltrating cells were mononuclear cells, mostly small lymphocytes. The population and frequency of these cellular infiltrations were weak generally; especially the infiltration into the pancreatic islet, which was very weak compared with that in NOD mice. Dilation of the proximal tubule occurred only in the females at 60 days or more after birth and it gradually increased with age. Numerous acidophil bodies appeared in the epithelial cells and the lumen of these dilated urinary tubules. These bodies were PAS-positive and stained with MT, and They had electron-dense complex structures.

Fine structure of the parotid gland in the pika and the volcano rabbit.

The parotid glands of the pika and the volcano rabbit were examined by light and transmission electron microscopy. The acinar cells of the pika consisted of light cells containing basophilic granules of low density, while in the volcano rabbit the acinar cells consisted of light and dark cells containing acidophilic granules of moderate density. Intercalated duct cells were composed of light cells containing a few granules of moderate density. These segments of the two animals were similar in morphology. The striated duct cells in both species were composed of light and dark cells. Most of those in the pika contained a few moderately dense granules. In both animals, no myoepithelial cells were detected around the acini, intercalated ducts or striated ducts, while nerve terminals were observed among the adjacent acinar cells.

Fine structure of the mandibular gland in pika (Ochotona rufescens rufescens).

The mandibular gland of the pika was examined by light microscopy, and transmission and scanning electron microscopies. The acinar cells were noted to be composed of serous cells and seromucous cells. The serous cells containing granules of moderate and high densities were slightly basophile and strongly positive to PAS, but were not stained with AB. The seromucous cells possessing less dense granules were light and moderately positive to PAS and AB. A sexual dimorphism was observed between these cells: Serous cells were considerably more frequent in males and seromucous cells were more numerous in females. Intercalated duct cells consisted of cuboidal light cells containing a few vesicles in the apical region. Striated ducts were comprised of two portions--a secretory portion and a typical striated portion without secretory granules. The secretory portion was composed of light and dark cells having secretory granules varying in size and density. The epithelium of typical striated portion consisted of light and dark cells containing fine vacuoles and vesicles.

Fine structure of the mandibular gland of the Djungarian hamster (Phodopus sungarus).

The mandibular gland of the Djungarian hamster was examined by light microscopy, and transmission and scanning electron microscopies. Its acinar cells reacted with periodic acid-Schiff (PAS) and were weakly stained with alcian blue (AB). There were intercellular canaliculi between the acinar cells. These cells therefore appeared to be seromucous. The acinar epithelium was composed of light cells containing various spherical secretory granules. The granular cells of the mandibular gland possessed many acidophilic granules exhibiting a positive reaction to PAS stain. They were frequently observed at the junction of the acini and intercalated ducts in all mandibular glands examined. All of these cells were light and contained secretory granules of varying size and density. The intercalated ducts consisted exclusively of light cells possessing a few round granules of high density in the apical region. The striated ducts were comprised of two portions--a secretory portion and a typical striated portion without secretory granules. The secretory portion consisted of light, dark and specifically light epithelial cells containing acidophilic granules, which exhibited a strongly positive PAS reaction. The epithelium of typically striated portions was composed of light and dark cells containing fine vacuoles in the apical region. The mandibular gland of the Djungarian hamster revealed no histological differences between sexes.

Fine structure of the parotid gland of Djungarian hamster (Phodopus sungarus).

The parotid glands of Djungarian hamster were examined by the light and electron microscopy. The acinar cells contained acidophile granules and reacted with the periodic acid-Schiff (PAS) and stained slightly with alcian blue (AB); they were thought to be seromucous in nature. The acinar epithelia were composed of light cells, dark cells and specific light cells containing spheroid granules. Cytoplasmic crystalloids of moderate to high densities were observed in nearly all light cells. The intercalated duct cells were composed of light cells alone, and contained the granules of moderate density in the apical and supranuclear regions. The striated duct cells consisted of light and dark cells. The most of these cells contained small granules of low to high densities in the apical and supranuclear regions. Myoepithelial cells were detected around the acini, and nerve terminals were observed among the adjacent acinar cells. The parotid gland of Djungarian hamster revealed no histological differences between the sexes.