Observation of Λ(4)H Hyperhydrogen by Decay-Pion Spectroscopy in Electron Scattering.

At the Mainz Microtron MAMI, the first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a (9)Be target in order to study the Λ binding energy of light hypernuclei. Positively charged kaons were detected by a short-orbit spectrometer with a broad momentum acceptance at 0° forward angles with respect to the beam, efficiently tagging the production of strangeness in the target nucleus. Coincidentally, negatively charged decay pions were detected by two independent high-resolution spectrometers. About 10(3) pionic weak decays of hyperfragments and hyperons were observed. The pion momentum distribution shows a monochromatic peak at pπ≈133 MeV/c, corresponding to the unique signature for the two-body decay of hyperhydrogen Λ(4)H→(4)He+π(-), stopped inside the target. Its Λ binding energy was determined to be BΛ=2.12±0.01 (stat)±0.09 (syst)MeV with respect to the (3)H+Λ mass.

Differential effects of sex steroid hormones on the expression of multiple first exons including a novel first exon of prolactin receptor gene in the rat liver.

In addition to the known four alternative first exons E1(1), E1(2), E1(3) and E1(4) of the rat prolactin receptor (PRL-R) gene, a novel first exon, E1(5), was identified by cDNA cloning of the 5'-end region of PRL-R mRNA in the rat liver. Genomic fragments containing E1(5) and its 5'- or 3'-flanking regions were also cloned from rat kidney genomic DNA. A sequence search for E1(5) revealed that E1(5) is located 49 kb upstream of exon 2 of the PRL-R gene in rat chromosome 2q16. RT-PCR analysis revealed that E1(5) was preferentially expressed in the liver, brain and kidney. Expression profiles of E1(2)-, E1(3)- and E1(5)-PRL-R mRNAs in the liver of male and female rats at 5 days of age and those at 8 weeks of age were examined by RT-PCR. The levels of E1(2)-PRL-R mRNA in the female rat increased remarkably in rats at 8 weeks of age compared with those at 5 days of age, and the levels of E1(5)-PRL-R mRNA in the male rat decreased markedly at 8 weeks of age compared with those at 5 days of age. In the female rat, the levels of E1(2)-PRL-R mRNA at 8 weeks of age decreased with ovariectomy performed at 4 weeks of age and recovered with the administration of beta-oestradiol. On the contrary, the levels of E1(5)-PRL-R mRNA increased with ovariectomy and decreased with the oestrogen treatment. In the male rat liver, the levels of E1(2)-PRL-R mRNA at 8 weeks of age increased strikingly with castration performed at 4 weeks of age and became undetectable with the administration of testosterone. The levels of E1(5)-PRL-R mRNA increased slightly with castration and were restored by testosterone treatment. Removal of gonadal tissues and sex steroid hormone treatment had no effect on the expression levels of E1(3)-PRL-R mRNA in both female and male rat livers. These results indicated that the expression of the PRL-R gene in the liver is regulated by the differential effects of sex steroid hormones on the transcription of the multiple first exons including the novel one.

Copulatory behavior of sexually naive and sexually experienced male rats following removal of the vomeronasal organ.

The question addressed was whether removal of the vomeronasal organ (VNO) of the male rat would produce observable deficits in sexual behavior. Both sexually naive and sexually experienced males were used and each animal was given more than 12 hours to mate with a receptive female. Although sexual arousal was depressed in both groups, and depressed more among naive than experienced animals, every male was eventually aroused by the receptive female and eventually ejaculated. We conclude that while the VNO contributes to arousal it is not indispensable for arousal.

Sexual behavior in the female rat following removal of the vomeronasal organ.

We used female Wistar rats from which the vomeronasal organ (VNO) has been removed. The first question addressed was whether such females would show deficits in sexual behavior. The data left no doubt that removal of the VNO severely depressed lordosis as well as such proceptive behaviors as "darting" and "hopping." We then injected estrogen and progesterone and, in still another experiment, estrogen and luteinizing hormone-releasing hormone (LHRH). Estrogen and progesterone significantly enhanced lordosis, but only estrogen and LHRH raised the lordosis quotient of VNO-ablated females to that of the control females. We discuss the results in terms of a theoretical model involving the complementary action of estrogen and LHRH in inducing lordosis in the intact female.

[Effects of the long-term administration of methamphetamine on body weight, food intake, blood biochemistry and estrous cycle in rats].

We have a big problem with the abuse of amphetamine and its close relative, methamphetamine (MAP) in Japan. As an animal model of people who abuse MAP, male and female rats were treated with MAP (0.1-10.0 mg/kg/day) for a long time. The results obtained in the present study were as follows. 1. Body weights in MAP-treated groups showed a dose-dependent decrease with loss of food intake. 2. Food intake in rats treated with MAP decreased, compared with the control, but when treatment with MAP was discontinued, food intake increased dramatically. 3. In a blood biochemistry assay, the turnover of protein and lipid was suppressed in rats after MAP. 4. The administration of MAP appeared to disturb the estrous cycle in female rats.

Prolactin levels and maternal behavior induced by ultrasonic vocalizations of the rat pup.

The relationship among ultrasonic vocalization (USV), prolactin and maternal behavior was investigated in lactating rat mothers and their pups. The lactating mother had a cannula inserted into the external jugular vein, and was exposed to USVs emitted from a pup immediately. Changes of prolactin and maternal behavior were determined. Prolactin increased dramatically during exposure to USVs, when maternal search, retrieving and nest building behavior appeared significantly. These results suggested that the relationship among USV, prolactin and maternal behavior was included in communication between lactating mother and pup.

Functional natural killer T cells in experimental mouse strains, including NK1.1- strains.

Natural killer T (NKT) cells are a newly discovered subset of lymphocytes. It appears that this subset has potential as important regulators of immune responses. But because there are relatively few NKT cells in lymphoid organs and because of technical difficulties in detecting NKT cells in most mouse strains, the roles of NKT cells have not been fully identified and little attention has been paid to the roles of NKT cells in immunological experiments in which NK1.1- strains were used. To examine the existence of functional NKT cells in various strains of experimental mice, including NK1.1- strains, we utilized alpha-galactosylceramide (KRN7000) which is thought to react specifically with NKT cells. Indeed, we could confirm that early cytokine (IL-4 and IFN-gamma) secretion at 2 h after the injection of KRN7000 was dependent on NKT cells. With this in vivo system, we have successfully detected the presence of functional NKT cells in various mouse strains, including AKR/N, BALB/c, C3H/HeJ, C3H/HeN, C57BL/6, C.B-17, CBA/N, NC, NOD, SJL, W/Wv, aly/aly and aly/+. Notable increases of serum IL-4 were detected in W/Wv and aly/+ strains, and defective response of IFN-gamma in SJL mice and that of IL-4 in NOD mice were observed. This is the first report to show the functional significance of NKT cells in cytokine secretion in various mouse strains in response to a ligand for the T cell receptor of NKT cells.

Marking behavior is innate and not learned in the Mongolian gerbil.

We studied whether marking behavior in Mongolian gerbils would be innate or learned behavior. The marking behavior was defined as "animals rubbing their abdominal scent glands on small protruding objects". Between 21 and 90 days of age, Mongolian gerbils, which were kept under such conditions that they would be unable to learn this behavior, were observed at intervals of 5-15 days to find out if there were signs of the behavior or not. Six male and four female Mongolian gerbils were used for observing. Neonate Mongolian gerbils during the age of 3 to 28 days were fostered by ICR mother mice. Weaning Mongolian gerbils were then individually kept away from the others. Marking behavior was observed in 2 out of 6 males at 50 days of age and 2 of 4 females at 60 days and the mean frequency of the marking behavior for 10 min was 3.5 in the males and 5.0 in the females. These results suggest that marking behavior was innate and not learned behavior in Mongolian gerbils.

[Histological studies on postnatal development of the musk gland in house musk shrews (Suncus murinus)].

The development of the musk gland in house musk shrews aged 0 to 21 days was studied lectin histochemically. On about 3 days of age, the musk gland could be discriminated from surrounding skin. This organ developed markedly on days 3 to 7, and its development continued to 21 days of age. Histologically, on day 1, the bulges that should develop into musk glands were identified in the vicinity of hair germs. On days 3 to 7, these bulges developed markedly, and on day 21 their structure revealed almost the same morphology with that in mature musk glands. We used 7 lectins; ConA, RCA I, PNA, SBA, UEA-I, DBA, and WGA. On day 1, 6 lectins except for WGA labelled the cell of the musk gland. WGA began to label it on day 3. Until 7 days of age, lectins bound to only the cytoplasm of the cell of musk glands. On days 12, however, PNA and UEA-1 labelled the cell membrane equally, and RCA I labeled it on day 21.

Comparative study on isolation calls emitted from hamster pups.

Waveforms of isolation calls emitted from hamster pups, which were Syrian hamsters, Djungarian hamsters, and Chinese hamsters, were compared in a basic study on improving reproduction by decrease of cannibalism, because it was reported that maternal behavior was induced by isolation calls in rodents. Isolation calls of hamster pups, isolated from their mother and receiving cold stress, were collected by Real-Time Spectrogram (RTS), and calculated to spectrograms and power spectra by SIGNAL. Isolation calls consisted of ultrasonic vocalizations (USVs) and audible vocalizations (ADVs) in each species. Waveforms of isolation calls emitted by the hamster pups, were shown to have several characteristic features. In this study, the species specificity of isolation calls was shown in hamster pups. It would seem that the species specificity originates in the differences of sensitivity to cold stress via the autonomic nerve in hamsters.

p-Chloroamphetamine (PCA) suppresses ingestive behavior in male rats.

Ingestive behavior was activated in male rats by intraoral intake and intake from a bottle of 1-M solution of sucrose. Intraperitoneal injection of p-chloroamphetamine (PCA), releasing central 5-hydroxytryptamine (5-HT) from serotonergic nerve terminals, inhibited ingestion of the sucrose solution. Significant inhibition of sucrose intake by PCA was observed at 1.25 and 2.5 mg/kg dose in a bottle intake test, and at 5.0 mg/kg dose in an intraoral intake test. These findings suggested that 1.25 and 5.0 mg/kg of PCA suppressed appetitive ingestive behavior and consummatory ingestive behavior in male rats, respectively.

Observation of marking-like behavior, marking behavior, and growth of the scent gland in young Mongolian gerbils (Meriones unguiculatus) of an inbred strain.

A marking-like behavior (defined by authors), a marking behavior, and growth of the scent glands were observed in young Mongolian gerbils of an inbred strain. In males and females, a marking-like behavior, in which animals rub their abdominal scent glands on the floor, began to be seen at the age of 19 days and could be seen in almost all the gerbils at 22 days of age during the suckling period. The frequency of this behavior was highest at 60 days of age (males: 17.9/10 min, females: 15.4/10 min) and there was no sex difference. Marking behavior, in which animals rub their abdominal scent glands on small protruding objects, began to be seen at the age of 40 days in males and 50 days in females. The frequency of this behavior tended to increase until 90 days of age in males (13.7/10 min), but the levels were low (2.5-5.0/10 min) in females. The values in the male group therefore tended to be higher than that in the female group. Macroscopic scent gland pads were clearly observed at the age of 30 days in males, but not until 45 days of age in females. At the age of 45-90 days, the length of the scent gland pad in males and females was 2.1-2.8 and 1.6-1.7 cm, respectively and the width was 0.3-0.5 in males and 0.2-0.3 cm in females. During this period, the length and depth of the pads in males were significantly greater than those in females (p < 0.05). Histological examination of the structure of the scent glands after the age of 45 days showed that the development of clusters of acinar cells in females occurred much later than that in males, but the basic structure of these glands was similar in both sexes. These results suggest that the marking-like behavior was manifested although during the period when the scent glands had not yet developed, whereas true marking behavior first occurred when the glands were moderately well developed.

Simultaneous observation of ingestive and copulatory behavior of the male rat.

In a preliminary test male rats were allowed to ingest a 1 M solution of sucrose from a drinking spout. After daily intake of sucrose became stabilized, the males were given a sexually receptive or non-receptive female and the bottle filled with sucrose solution simultaneously. The ingestive and copulatory behavior was observed for 60 min under illumination by a red lamp. The data obtained from this study showed that the ingestive behavior of males was suppressed by the presence of sexually receptive females and, conversely, the sexual behavior of males was not affected by the presence of a bottle of sucrose. These results suggest that the presence of a sexual partner inhibits appetitive ingestive behavior, i.e., the responses used by male rats to obtain food.

[Age-related changes in the retina of WBN/Kob rats--a pathological study].

Male rats of the WBN/Kob strain, which are known to spontaneously develop diabetes with aging, were examined for histopathological changes in the retina. Five rats (10 eyes) each of WBN/Kob and Wistar/ST as a control were used, and the thickness of the retinal layers, both the central region and the peripheral region of the retina, were measured on weeks 1, 2, 3, 5, 9, 13, 17, 23, 27, 36, 45, 54, 67 and 80 after birth. The rod and cone cell layer in WBN/Kob rats was under-grown, and its thickness decreased 71.7% in the central zone and 59.3% in the peripheral zone of the retina compared with that of the control. In the central and peripheral retina, the rod and cone cell layer, outer nuclear layer and outer plexiform layer, as well as the inner plexiform layer in the central retina, gradually decreased in thickness from 5-45 weeks of age. In the central and peripheral parts of the retina, the number of nuclei decreased in accordance with the thinning of the nuclear layer. The thinned layers showed only cell loss. The rod and cone cell layer of the peripheral retina was thinner than that of the central retina. We obtained the following findings in the retina of male WBN/Kob rats. First, the rod and cone cell layer is undergrown compared with that of the control. Second, the first change occurred in the rod and cone cell layer. Third, the thinning of the rod and cone cell layer appeared at 5 weeks of age, and thinning with aging was slow. And finally, the thinning of the peripheral retina was more severe than that of the central retina. From the above findings, it seems that retinal changes in WBN/Kob rats are similar to the retinal degeneration of rds mice (retinal degeneration slow mice) and that WBN/Kob rats provide a useful animal model for human retinopathy.

Sedative effect of medetomidine and its reversal by atipamezole in house musk shrews (Suncus murinus).

This study was undertaken to evaluate the sedative effect of medetomidine, an alpha 2-adrenoceptor agonist, and the counteractive effect of atipamezole, an antagonist to medetomidine, in house musk shrews (Suncus murinus). Two hundred, 300, 400, or 600 micrograms/kg of medetomidine was intraperitoneal injected into 89 house musk shrews. A sedative effect was produced in one to two minutes after injection. The dose-dependent prolongation of the sedative duration and the dose-dependent appearance of a hypothermic effect were demonstrated. With 200 micrograms/kg of medetomidine, the sedative effect obtained was not adequate in some of the animals. With 300 micrograms/kg and above, a stable sedative state was induced in all the animals. The duration of sedation in the house musk shrews was much longer (p < 0.01) in males than in females. This suggested the higher susceptibility of male house musk shrews to this drug. The sedative effect and hypothermia obtained with 400 micrograms/kg of medetomidine were completely counteracted by more than 2.0 mg/kg of atipamezole. With 0.5 and 1.0 mg/kg of atipamezole, only a partial antagonistic action was produced. Transient vomiting appeared in 4.5% of the house musk shrews at approximately one minute after injection of medetomidine. This side-effect had occurred before the sedative effect was obtained, and was not serious enough to be a problem. None of the 89 house musk shrews died in this experiment. The above results show that the combination of medetomidine and atipamezole is a highly effective and safe anesthetic treatment which permits easy handling of house musk shrews.

Development of the Bowman's and Jacobson's glands in the Japanese reddish frog, Rana japonica.

The olfactory organs are equipped with their own associated glands, Bowman's glands (BG) of the olfactory epithelium (OE), and Jacobson's glands (JG) of the vomeronasal organ (VNO). Histology and ultrastructure of these glands in the adult were investigated in the Japanese reddish frog, Rana japonica, along with their development from hatching to the end of metamorphosis. In the adult, BG cells contained large, electron-opaque secretory granules, intensely PAS-positive by light microscopy, while JG cells contained middle-sized secretory granules with moderate electron density, only faintly PAS-positive. Embryologically, BG appeared within the OE at 44 days after hatch, increased in number and were situated in the lamina propria under the OE at 52 days after hatch. BG cells contained large, electron-opaque granules, and well-developed rER at this time. While, JG appeared much earlier than BG. The VNO appeared as a concave of the ventral part of the OE at 4 days after hatch, and JG appeared under the VNO at 10 days after hatch. JG cells contained well-developed rER at 12 days after hatch. Secretory granules appeared in a small number in JG at 24 days after hatch, and increased thereafter. These findings suggest that JG may take part in secretion earlier than BG in ontogeny.

Development of the olfactory epithelium and vomeronasal organ in the Japanese reddish frog, Rana japonica.

Histological and ultrastructural development of the olfactory epithelium (OE) and vomeronasal organ (VNO) was investigated in the Japanese reddish frog, Rana japonica. Tadpoles, from hatching to the end of metamorphosis, and adult frogs were examined. In the adult, olfactory cells of the OE were equipped with olfactory vesicles with long cilia, but supporting cells with microvilli. The supporting cells of the OE contained secretory granules, PAS-positive by light microscopy, in their apical cytoplasm. On the contrary, sensory cells of the VNO were equipped with microvilli, and supporting cells of the VNO were equipped with cilia, but without secretory granules. Embryologically, the olfactory cells were indistinguishable from the supporting cells in the olfactory placode (primitive OE) lining the nasal pit, at hatch. The VNO appeared as a concave of the ventral part of the OE at 4 days after hatch. At the time, the olfactory and supporting cells of the OE became distinguishable from each other. Secretory granules were formed in the supporting cells of the OE at 36 days after hatch, and the OE was similar in fine structure to that in the adult. While, the VNO remained immature at 24-36 days after hatch, and did not complete its ultrastructural development at 60 days after hatch, the end of metamorphosis. These findings suggest that the OE may take part in the olfaction earlier than the VNO in ontogeny.

A simple method for prevention of coprophagy in the mouse.

A series of studies of coprophagy in mice has been conducted from the viewpoints of behaviour and nutrition. Since it was necessary to prevent coprophagy to investigate its significance, an attempt was made to devise a restrainer. A polyethylene bottle was cut and fixed to the mouse so as to prevent its head from reaching its anus when faeces were excreted. The animals were also housed in cages with floors of larger mesh size in order to let the faeces fall through.

Para-chloroamphetamine (PCA)-induced ejaculation in aged rats, semen analysis and artificial insemination.

The present study was undertaken to determine sperm motility and counts in semen yielded by para-chloroamphetamine (PCA)-induced ejaculation of aged rats which had lost their reproductive ability, and to attempt artificial insemination with suspensions of spermatozoa obtained in this way. The semen yielded by PCA-induced ejaculation from aged (75-week-old) rats had average sperm counts of 0.82 +/- 0.69 x 10(7), which were much lower than the average counts (9.42 +/- 1.65 x 10(7)) for semen spontaneously ejaculated by young adult rats (14 weeks old). However, 77.5% of the spermatozoa contained in the PCA-induced semen were rated as showing the most active movement. Spermatozoa collected in this way were injected into the upper parts of both uterine horns or into both ovarian bursae. Both methods made the females pregnant, but the results were better after injection into the ovarian bursae. The offspring born to these females showed no abnormalities.

Obesity induced changes to plasma adiponectin concentration and cholesterol lipoprotein composition profile in cats.

Feline obesity generally results in aberrations to plasma metabolite levels, such as lipid concentrations and lipoprotein composition. This study sought to investigate the resultant effect of obesity on cholesterol lipoprotein composition and circulating adiponectin concentrations in cats. Plasma glucose, lipids (triglyceride, cholesterol and free fatty acid), insulin and adiponectin concentrations, and cholesterol lipoprotein composition were measured and compared between body condition score (BCS) determined normal healthy control and obese cats. Although the obese group demonstrated higher levels of plasma cholesterol, glucose, and triglycerides, as compared to healthy controls, the difference was insignificant thus indicating that the BCS determined obese cats may have been overweight and not morbidly obese. Plasma insulin levels were significantly higher (25-30%) versus healthy control animals thereby possibly hinting at the ensuing emergence of obesity induced insulin resistance. However, the BCS determined obese cat demonstrated a significant reduction (p<0.05) in plasma adiponectin concentration and a significant increase (p<0.05) in LDL-cholesterol % as compared to age matched healthy control animals. This would indicate that changes in plasma adiponectin concentration and cholesterol lipoprotein composition may be good early indicators of obesity in cats.