Normal Male Mouse Research Articles

Post-stroke angiotensin II type 2 receptor activation provides long-term neuroprotection in aged rats.

Activation of the angiotensin II type 2 receptor (AT2R) by administration of Compound 21 (C21), a selective AT2R agonist, induces neuroprotection in models of ischemic stroke in young adult animals. The mechanisms of this neuroprotective action are varied, and may include direct and indirect effects of AT2R activation. Our objectives were to assess the long-term protective effects of post-stroke C21 treatments in a clinically-relevant model of stroke in aged rats and to characterize the cellular localization of AT2Rs in the mouse brain of transgenic reporter mice following stroke. Intraperitoneal injections of C21 (0.03mg/kg) after ischemic stroke induced by transient monofilament middle cerebral artery occlusion resulted in protective effects that were sustained for up to at least 3-weeks post-stroke. These included improved neurological function across multiple assessments and a significant reduction in infarct volume as assessed by magnetic resonance imaging. We also found AT2R expression to be on neurons, not astrocytes or microglia, in normal female and male mouse brains. Stroke did not induce altered cellular localization of AT2R when assessed at 7 and 14 days post-stroke. These findings demonstrate that the neuroprotection previously characterized only during earlier time points using stroke models in young animals is sustained long-term in aged rats, implying even greater clinical relevance for the study of AT2R agonists for the acute treatment of ischemic stroke in human disease. Further, it appears that this sustained neuroprotection is likely due to a mix of both direct and indirect effects stemming from selective activation of AT2Rs on neurons or other cells besides astrocytes and microglia.

Chronic stress prior to pregnancy potentiated long-lasting postpartum depressive-like behavior, regulated by Akt-mTOR signaling in the hippocampus.

Postpartum depression (PPD) affects over 10% of new mothers and adversely impacts the health of offspring. One of the greatest risk factors for PPD is prepregnancy stress but the underlying biological mechanism is unknown. Here we constructed an animal model which recapitulated prepregnancy stress induced PPD and tested the role of Akt-mTOR signaling in the hippocampus. Female virgin Balb/c mice received chronic restraint stress, followed by co-housing with a normal male mouse. We found that the chronic stress led to a transient depressive-like condition that disappeared within two weeks. However, prepregnantly stressed females developed long-term postpartum depressive-like (PPD-like) symptoms as indicated by deficient performance in tests of sucrose preference, forced swim, and novelty-suppressed feeding. Chronic stress induced transient decrease in Akt-mTOR signaling and altered expressions of glutamate receptor subunits NR1 and GluR1, in contrast to long-term deficits in Akt-mTOR signaling, GluR1/NR1 ratio, and hippocampal neurogenesis in PPD-like mice. Acute ketamine improved the molecular signaling abnormality, and reversed the behavioral deficits in PPD-like mice in a rapid and persistent manner, in contrast to ineffectiveness by chronic fluoxetine treatment. Taken together, we find that chronic prepregnancy stress potentiates a long-term PPD, in which Akt-mTOR signaling may play a crucial role.

Antifertility Activity in the Acetone Extracts of Datura metel, L Seeds on Female Mouse

The present study shows the antifertility activity in the acetone extracts of Datura metal L. in female albino mouse. The crude extract of Datura metel seeds were administered orally to the female mouse (25 gm of bodyweight) in the concentration of 0.5%, 1% and 2% respectively. Control was maintained using NaCl solution. After 15th day of treatment the female mouse was mated with the normal male mouse in the ratio of 1:3. After 10 days of mating they were dissected and observed the number of implantation sites in the uterine horns. The results stated that the females treated with 2% seed extracts caused cent percent anti-implantation activity followed by 1% and 0.5% seed extracts caused 40% and 80% anti implantation activity respectively. The results of the present study concludes that the seed extracts of Datura metel L may be recommended as a good source of antifertility inducious compounds with minimal side effects after testing in the other human models.

Organ dose conversion coefficients based on a voxel mouse model and MCNP code for external photon irradiation

A set of conversion coefficients from kerma free-in-air to the organ absorbed dose for external photon beams from 10 keV to 10 MeV are presented based on a newly developed voxel mouse model, for the purpose of radiation effect evaluation. The voxel mouse model was developed from colour images of successive cryosections of a normal nude male mouse, in which 14 organs or tissues were segmented manually and filled with different colours, while each colour was tagged by a specific ID number for implementation of mouse model in Monte Carlo N-particle code (MCNP). Monte Carlo simulation with MCNP was carried out to obtain organ dose conversion coefficients for 22 external monoenergetic photon beams between 10 keV and 10 MeV under five different irradiation geometries conditions (left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic). Organ dose conversion coefficients were presented in tables and compared with the published data based on a rat model to investigate the effect of body size and weight on the organ dose. The calculated and comparison results show that the organ dose conversion coefficients varying the photon energy exhibits similar trend for most organs except for the bone and skin, and the organ dose is sensitive to body size and weight at a photon energy approximately <0.1 MeV.

Impact of Mouse Model on Preclinical Dosimetry in Targeted Radionuclide Therapy

Small animal dosimetry serves as an important link in establishing a relationship between absorbed dose and biological effect during preclinical targeted radionuclide therapy. Dosimetric approaches reported to date are based on models aiming at representing the animals used during preclinical experiments. However, anatomical variations between models may generate differences in the dosimetric results. Our goal was to assess the impact of the mouse model on the absorbed dose per cumulated activity (S-value, in gray per becquerel-seconds). Two datasets were considered. The first one was developed in our laboratory and is a voxel-based model of a 30-g female nude mouse. Images were segmented manually to identify more than 30 organs and suborgans. The second dataset originates from the DIGIMOUSE project. In that model, a 28-g normal male nude mouse was used to generate the segmented structures of nine regions in the head and 12 major organs. A software developed in our laboratory allowed us to read each three-dimensional mouse atlas slice by slice, to crop the mouse volume to remove background air voxels, and to write the geometry description as an input file for the Monte Carlo code MCNPX using repeated structure representation. A linear interpolation scales the voxel size as a function of the total body mass. The comparison of various voxel-based mouse dosimetric models shows that even when scaled to the same total-body mass, models from different mouse breed or gender demonstrate very different organ masses, volumes, and, therefore, S-values. Computation of the S-values for preclinical studies depends strongly on the definition of the mouse model. Our computational model is a step in the direction of a more realistic description of the geometry in preclinical dosimetry.

Epithelial cells are the major site of hydroxysteroid (17β) dehydrogenase 2 and androgen receptor expression in fetal mouse lungs during the period overlapping the surge of surfactant

Many genes involved in the peripheral metabolism of androgens, including hydroxysteroid (17β) dehydrogenases (HSD17B) 2 and 5, steroid 5α reductase 1, and 3α-HSD, are expressed in the developing lung. Because lung development is delayed by androgens and pathologies related to lung immaturity are major concerns for preterm neonates, we are interested in the elucidation of the androgen metabolism in developing lung. In the present report we have identified the cell types expressing HSD17B2 (testosterone into androstenedione) and androgen receptor in normal male and female mouse developing lung between the gestation days 15.5 and 17.5. In situ hybridization and immunohistochemistry revealed that HSD17B2 is expressed in epithelial cells of respiratory and conducting zones, and in mesenchymal cells. The androgen receptor protein was observed in the same cell types that HSD17B2, and in α-smooth muscle actin-positive cells surrounding arteries. No difference was observed for the location of HSD17B2 and androgen receptor expression at any time points studied, or according to sex. Taken together, our results are in concordance with the hypothesis that in mouse fetal lungs the level of androgen receptor occupancy is finely tuned by local HSD17B2 expression.

Extracts from salivary glands stimulate aggression and inositol-1, 4, 5-triphosphate (IP 3) production in the vomeronasal organ of mice

Mammals use chemical cues to coordinate social and reproductive behaviors. Chemical cues are detected by the VNO organ (VNO), which is a cartilage-encased elongated organ associated with the vomer bone in the rostral nasal cavity. The resident intruder paradigm was utilized to examine the ability of saliva and its feeder exocrine glands, the submaxillary, parotid, and sublingual glands to mediate aggression in mice. Saliva and extracts from submaxillary and parotid glands, but not extracts from sublingual glands of male CD-1 mice, induced a greater number of attacks and lower latencies to sniff and attack ( p < 0.05) and significantly increased IP 3 production ( p < 0.05) versus vehicle (PBS) in CD-1 male mice VNO. We further show that CD-1 male mouse saliva and submaxillary gland extract induced significantly more attacks and a lower latency to attack in lactating female CD-1 mice and produced significantly more inositol triphosphate (IP 3), indicative of phospholipase C β signaling which mediates pheromonal activity, in CD-1 female VNO compared to PBS. Castrated CD-1 male mouse saliva, and exocrine gland extracts induced significantly less IP 3 production in male VNO and less aggression by CD-1 males and lactating females compared to responses to normal CD-1 male mouse saliva and gland extracts. Thus, chemical cues present in saliva, submaxillary and parotid glands of CD-1 male mice are capable of stimulating aggression in male and female congenic mice which are correlated with significant production of IP 3 in the VNO. Additionally, these stimulations of aggression and IP 3 production are shown to be androgen-dependent.

α‐Lipoic acid reduces congenital malformations in the offspring of diabetic mice

The mechanism of diabetes-induced congenital malformation remains to be elucidated. It has been reported that alpha-lipoic acid (LA) prevents neural tube defects (NTDs) in offsprings of rats with streptozotocin-induced diabetes. Here, we evaluate the protective effect of LA against diabetic embryopathy, including NTDs, cardiovascular malformations (CVMs), and skeletal malformations, in mice. Female mice were rendered hyperglycemic using streptozotocin and then mated with normal male mouse. Pregnant diabetic or non-diabetic mice were treated daily with either LA (100 mg/kg body weight) or saline between gestational days 0 and 18. On day 18, fetuses were examined for congenital malformations. Plasma glucose levels on day 18 were not affected by LA treatment. No congenital malformations were observed either in the saline-treated or LA-treated non-diabetic group. In the saline-treated diabetic group, 39% of fetuses had external malformations and 30% had NTDs. In the LA-treated diabetic group, the corresponding proportions were 11 and 8%, respectively. LA treatment also decreased the incidence of CVMs from 30-3% and of skeletal malformations from 29-6%. We conclude that LA can reduce NTDs, CVMs and skeletal malformations in the offspring of diabetic mice at term delivery.

Modified progesterone receptor expression in the hypothalamus of cysticercotic male mice

Progesterone participates in numerous developmental and behavioral processes in the mammalian brain. The intracellular (is this really intracellular? nuclear membrane?) progesterone receptor is expressed as two isoforms: a full-length form (PR-B) and the N-terminally truncated one (PR-A). Experimental intraperitoneal infections with Taenia crassiceps in mice exhibit the tendency of the parasites to develop more rapidly in females. Male mice undergo a feminization process characterized by their oestrogenisation, deandrogenisation and loss of sexual and aggressive patterns of behavior. Hence, we suspected that changes in PR expression in the brain could be involved in the feminization of the infected male mice and in the loss of the sexual and aggressive behaviors. We have studied the expression of PR isoforms in the normal and infected male mouse brain. Transcripts of both receptor isoforms (PR-A and -B) were readily detectable in normal and infected mice, but differentially regulated during infection depending on the area of the brain studied. Although the precise role of progesterone in mediating the behavioral changes noted during infection is not fully understood, our data implicate a role for PR signaling in the feminization process. CNS activity is potentially involved in the network that regulates the oestrogenisation and deandrogenisation observed in chronically infected male mice, as well as in the behavioral peculiarities observed in this parasitic infection.

Digimouse: a 3D whole body mouse atlas from CT and cryosection data

We have constructed a three-dimensional (3D) whole body mouse atlas from coregistered x-ray CT and cryosection data of a normal nude male mouse. High quality PET, x-ray CT and cryosection images were acquired post mortem from a single mouse placed in a stereotactic frame with fiducial markers visible in all three modalities. The image data were coregistered to a common coordinate system using the fiducials and resampled to an isotropic 0.1 mm voxel size. Using interactive editing tools we segmented and labelled whole brain, cerebrum, cerebellum, olfactory bulbs, striatum, medulla, masseter muscles, eyes, lachrymal glands, heart, lungs, liver, stomach, spleen, pancreas, adrenal glands, kidneys, testes, bladder, skeleton and skin surface. The final atlas consists of the 3D volume, in which the voxels are labelled to define the anatomical structures listed above, with coregistered PET, x-ray CT and cryosection images. To illustrate use of the atlas we include simulations of 3D bioluminescence and PET image reconstruction. Optical scatter and absorption values are assigned to each organ to simulate realistic photon transport within the animal for bioluminescence imaging. Similarly, 511 keV photon attenuation values are assigned to each structure in the atlas to simulate realistic photon attenuation in PET. The Digimouse atlas and data are available at http://neuroimage.usc.edu/Digimouse.html.

Developmental Expression and Localization of IA-2 mRNA in Mouse Neuroendocrine Tissues

Islet antigen (IA)-2 is a novel autoantigen of insulin-dependent diabetes mellitus (IDDM), and belongs to a new class within the receptor-type protein tyrosine phosphatase (PTP) family characterized by lack of PTP enzymatic activity with conventional substrates. Its expression is restricted primarily to the pancreas, pituitary, and brain with the highest level in the brain. IA-2 mRNA expressions in the brain, pituitary and pancreas of 1-, 4-, and 8-week-old mice were examined. In situ hybridization of the brain revealed that IA-2 mRNA was expressed in the cerebral cortex, hippocampus, thalamus, choroid plexus, hypothalamus, Purkinje cells, and granular layer of the cerebellum. In the pituitary, IA-2 mRNA was located in the anterior and posterior pituitary by in situ hybridization. The pattern of IA-2 mRNA expression in normal male mouse brain at 1, 4, and 8 weeks of age by the Northern blot analysis was similar to that in the pituitary by RT-PCR analysis. The expression level was higher at 4 weeks and lower at 1 week of age. In the pancreas, IA-2 mRNA expressions detected by RT-PCR were highest at 8 weeks of age. These results indicated that the amount of mRNA expression increased in accordance to development in brain, pituitary, and pancreas.

Corrections in counting paired nuclei labelled with bromodeoxyuridine in tissue sections

Bromodeoxyuridine is finding increasing use as an alternative to, or in conjunction with, tritiated thymidine for labelling nuclei in DNA synthesis. Precise identification of labelled nuclei is possible, even when there is considerable overlap between neighbouring nuclei. In the sparsely labelled renal cortex of the normal male mouse, 'flash labelling' with bromodeoxyuridine shows single labelled nuclei at 1 h. At 24, 48 and 72 h after injection of bromodeoxyuridine, some labelled cells are seen to lie adjacent and such labelled pairs are presumed to be the result of cell division. Single labelled nuclei at 24, 48 and 72 h might indicate arrest in DNA synthesis or a prolonged G2 period, but it is important to recognize that a correction must be made for paired labelled nuclei in which one member is out of the plane of section. The factors involved in making such a correction are discussed and a correction table calculated. In the normal male mouse renal cortex, we show that nearly all cells labelled at 1 h had divided by 72 h.

Sex chromosome configurations in pachytene spermatocytes of an XYY mouse

Karyotypic investigation of a phenotypically normal but sterile male mouse showed the presence of an XYY sex chromosome constitution. The synaptic behaviour of the three sex chromosomes was examined in 65 pachytene cells. The sex chromosomes formed a variety of synaptic configurations: an XYY trivalent (40%); an XY bivalent and Y univalent (38.5%); an X univalent and YY bivalent (13.8%); or X, Y, Y univalence (7.7%). There was considerable variation in the extent of synapsis and some of the associations clearly involved nonhomologous pairing. These observations have been compared with previously published information on chromosome configurations at metaphase I from other XYY males.

Aggression-provoked huge release of submaxillary mouse renin to saliva

In a normal male mouse, which had been kept isolated for some time, confrontation with another male mouse, resulted in aggressive behaviour, including fighting. The aggressive behaviour resulted in secretion of a few microlitre of saliva with vast renin concentration. The renin concentration in saliva reached values of 6000 Goldblatt units X ml-1, corresponding to 15 mg/ml of renin. This concentration is 6 orders of magnitude higher than normal plasma renin concentrations. The secretory pattern could be mimicked by ip injection of pharmacological doses (2-18 mg/kg) of the alpha-adrenergic agonist phenylephrine. This is probably the first demonstration of a physiological secretion of renin to saliva which may be of importance since renin most likely is injected into the opponent or prey through bites.

A 41, XYY mouse

Cytogenetic analyses of bone marrow and meiotic cells in an apparently normal male mouse clearly revealed the presence of an extra Y chromosome leading to 2n=41, XYY. During meiosis the sex chromosomes formed all possible types of combinations (XYY, XY/Y, YY/X and X/Y/Y). Compared to 40, XY normal mice, the sperm count was significantly less, but the incidence of sperm head abnormality was at the normal level.

Observations on the growth of the normal male mouse.

The pattern of body weight gain, the longitudinal growth of the humerus and the changes in the width of its proximal growth plate were determined in normal ICR male mice. The respective growth rates were calculated and compared throughout the animals' first year of life. It was found that the overall growth period can be divided into four phases which differ markedly in their growth rate. Whereas skeletal maturation is reached at the age of 20 weeks, the animals' body weight continues to increase up to the end of the 52nd week. The humeral growth plate retains its existence and function until old age is reached, i.e. 15 months. During the period of highest growth activity extending between weanling and sexual maturation, the growth velocities of the various parameters do no coincide.

In vivo Hybridisation of Cultured Melanoma Cells and Isogenic Normal Mouse Cells

Somatic cell hybrids were derived by fusing tumourigenic and melanogenic melanoma (PAZG) cells with normal diploid male mouse cells in vivo. Their chromosomal composition was equivalent to the sum of both parental genomes and included a Y chromosome lacking in the melanoma parent. Our study showed that in PAZG X C57BL hybrids (MP), tumourigenicity was suppressed but pigmentation was expressed.

The effect of the mouse X-linked Testicular feminization mutation on the hypothalamus-pituitary axis. I. Paradoxical effect of testosterone upon pituitary gonadotrophs.

Testosterone exercises a negative feedback upon pituitary gonadotrophs, paiticularly presumptive LH producers, of both the normal male and normal female mouse. In sharp contrast, the effect of testosterone upon the corresponding cells of Tfm/Y♂ can best be described as a positive feedback. These cells of Tfm/Y♀ atrophy after castration and show remarkable hypertrophy in response to continuous administration of testosterone.

An XYY sex-chromosome constitution in the mouse.

A phenotypically normal male mouse, investigated because it was sterile, was found to possess 41 chromosomes. A karyotypic analysis indicated the extra element was one of the smallest chromosomes, almost certainly the Y. X-Y bivalents, Y-Y bivalents and XYY univalents were seen in meiotic metaphase I cells, and it was therefore concluded that the extra chromosome was indeed the Y. Spermatogenesis tended to break down after meiosis I, but a few spermatids and sperm were observed.

Ultrastructure of mouse submaxillary gland: I. Sexual differences

Normal male and female mouse submaxillary glands have been studied by light and electron microscopy. The female gland is characterized by the presence of secretory granules in the intercalated duct nearest the acinus and a striated secretory tubule, i.e., a tubule with basal mitochondria similar to a striated duct but also containing secretory granules in the apical cytoplasm. The striated secretory tubule is found following the intercalated duct. The male has a very prominent secretory tubule in which two types of cells are present, one relatively clear, the other the dark cell of Pfluger. A striated secretory tubule is absent in the male. The male secretory tubule is also characterized by the presence of intracellular canaliculi.