Male Golden Hamsters Research Articles

The influence of handling and exposure to a ferret on body temperature and running wheel activity of golden hamsters ( Mesocricetus auratus)

In order to determine a stress response, two groups of twenty male golden hamsters were either exposed to a ferret or handled by a human. The hamsters’ body temperature and running wheel activity were measured as stress correlates. Half of the hamsters’ cages were equipped with a functional running wheel to determine whether the presence of a running wheel might reduce stress. Exposure to the ferret was followed by a significant increase in body temperature and running wheel revolutions; however, running wheel activity did not change after handling. Body temperature increased less after handling in hamsters living in a cage with a functional running wheel than in those with a non-revolving running wheel. This suggests that hamsters with a functional running wheel reacted less strongly to acute stress caused by handling. On the other hand, temperature increase after the exposure to a ferret was not affected by the presence of a running wheel. Both exposure to a ferret and handling caused stress in golden hamsters, as demonstrated by an increase in body temperature (emotional fever). Stress caused by handling was much milder than stress caused by the ferret.

Effects of red mold dioscorea on oral carcinogenesis in DMBA-induced hamster animal model

Monascus-fermented products offer valuable therapeutic benefits and have been extensively used for centuries in East Asia. Dioscorea has been proved to have anti-cancer effect. The aim of this study is to investigate the anti-tumor ability of the ethanol extract of red mold dioscorea (RMDE) on 7,12-dimethyl-1,2-benz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. We induced oral squamous cell carcinoma (OSCC) in the buccal pouch of male Syrian golden hamsters by painting with 0.5% DMBA three times a week for 14weeks. From 9 to 14weeks, a dose of 50, 100, and 200mg RMDE per kg body weight were painting with the hamsters for 6weeks on days alternate to the DMBA application. The results demonstrated that RMDE decreased nitric oxide (NO), reactive oxygen species (ROS), and prostaglandin E2 (PGE2) overexpression in hamster buccal pouches in the DMBA treatment group and increased p53, serum tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) to significantly stimulate caspase-8 and -3 activities, indicating that RMDE reduced oxidative damage causing by DMBA and induced apoptosis in oral cancer cells. Therefore, RMDE may have therapeutic potentials against OSCC.

Aberrant expression in multiple components of the transforming growth factor-β1-induced Smad signaling pathway during 7,12-dimethylbenz[a]anthracene-induced hamster buccal-pouch squamous-cell carcinogenesis

Transforming growth factor (TGF)-β1 signaling controls a plethora of cellular processes including tumorigenesis. The TGF-β1 ligand initiates signaling by binding to TGF-βreceptor II (TβRII) and allowing heterodimerization with TGF-βreceptor I (TβRI); thus, TβRI is phosphorylated by TβRII. After phosphorylation, Smad2 and Smad3 heterodimerize with Smad4, and this complex migrates to the nucleus to regulate the expression of specific target genes. However, Smad7 interrupts above signal transduction by preventing phosphorylation of Smad2 or Smad3. The objective of this study was to examine the TGF-β1-induced Smad signaling pathway during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal-pouch squamous-cell carcinogenesis. Fifty 6-week-old male Syrian golden hamsters were divided into three experimental and two control groups (10 animals in each). Both pouches of each animal in the experimental groups were painted with 0.5% DMBA solution, and both pouches of each animal of one of the control groups were similarly treated with mineral oil; the other control group remained untreated throughout the experiment. Animals from three experimental groups were sacrificed at the end of 3rd, 9th, and 14th-weeks after DMBA treatment, respectively, and animals from two control groups were all sacrificed at 14th-weeks after the treatment. Immunohistochemical staining for TGF-β1, TβRI, TβRII, Smad2-4 and Smad7 were performed. A significant increase in the expression of Smad7 and significant decreases in the expression of TβRII, Smad 2, Smad3 and Smad4 were noted during hamster buccal-pouch carcinogenesis induced by DMBA. Our findings indicate that a disruption in TGF-β1-induced Smad signaling occurs as a result of aberrant expression of multiple components in the TGF-β1 signaling pathway during DMBA-induced hamster buccal-pouch carcinogenesis, leading to loss of TGF-β1 growth-suppressive effects on transformed pouch keratinocytes.

Effect of cigarette smoke on mutagenic activation of environmental carcinogens by cytochrome P450 2A8 and inactivation by glucuronidation in hamster liver

To elucidate the mechanism underlying suppression of N-nitrosobis(2-oxopropyl)amine (BOP)-induced hamster pancreatic carcinogenesis by cigarette smoke (CS), hepatic levels of microsomal cytochrome P450 (CYP) enzymes, mutagenic activation of environmental carcinogens and three types of uridine diphosphate-glucuronyltransferase (UDPGT) and sulphotransferase (ST) activities were assayed in male Syrian golden hamsters and F344 rats exposed to CS. Immunoblot analyses of microsomal CYP proteins revealed induction of constitutive CYP1A2 (2.6-fold increase) and 2A8 (4.0-fold increase) and induction of CYP1A1 and constitutive CYP1A2 (3.9-fold increase) in rats following exposure to CS for 4 weeks using a Hamburg type II smoking machine. CS exposure enhanced mutagenicities of four heterocyclic amines in the presence of liver S9 in both species, whereas the mutagenicities of aflatoxin B(1) (AFB(1)), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were significantly increased by CS in hamsters but not in rats. However, no CS-induced alterations in the mutagenic activities of other carcinogens, including BOP and other pancreatic carcinogens, were observed in either species. Application of several CYP inhibitors revealed that the mutagenic activities of MeAαC, AFB(1) and NNK in the hamster liver S9 were partly associated with CYP2A8, whereas those of the three pancreatic carcinogens were selectively associated with CYP2B. CS enhanced UDPGT activities towards 4-nitrophenol (4-NP) (1.9- to 2.0-fold) but did not affect those of bilirubin, testosterone UDPGTs and three STs in both species. Together with the previous findings that BOP does not induce tumourigenesis in rats and that the glucuronidation of β-oxypropylnitrosamines is higher in rats than in hamsters, suppression of BOP-induced pancreatic carcinogenesis by CS might be attributed to increased detoxification by 4-NP UDPGT and not decreased CYP2B activation. This is the first demonstration of the induction of CYP2A protein by CS; CYP2A protein polymorphisms have been associated with oral and pulmonary carcinogenesis in smokers.

Antidiabetic and antidyslipidemic activities of Cuminum cyminum L. in validated animal models

The ethanolic extract of seeds of Cuminum cyminum (C.c) was found to improve glucose tolerance to the tune of around 18.3% (P < 0.01) in normal rats and shows around 17.7% (P < 0.01) and 17.1% fall on blood glucose levels at 0–300 and 0–1440 min, respectively, on streptozotocin-induced diabetic rats at an oral dose of 250 mg/Kg body weight. The extract has also been found to improve around 26.7% (P < 0.01) glucose intolerance on 14th day post treatment in high fructose fed streptozotocin-induced diabetic rats. The extract was also found to have antidyslipidemic activity as evident by 21.04% (P < 0.01) decline in serum triglycerides, 22.7% (P < 0.01) decline in total serum cholesterol, and 16.9% of decline in serum LDL-C, respectively, along with 12.2% (P < 0.05) increase in serum HDL-C on high fat diet fed male Syrian golden hamster. The extract was also found inhibitory to eye lens aldose reductase (EC 1.1.1.21) with IC50 value of 7.07 μg/ml as compared to the standard AR inhibiting compound Quercetin which showed IC50 2.35 μg/ml. The extract was also found inhibitory to α-glucosidase with IC50 value of 100 μg/ml as compared to known drug Acarbose which showed IC50 of around 25 μg/ml.

Characterization of behavioural responses in different test contexts after a single social defeat in male golden hamsters (Mesocricetus auratus)

The objective of the present study was to characterize behavioural responses of male hamsters in each of three test contexts after they had experienced either a single social defeat or a neutral encounter. In experiment 1, hamsters were observed in a familiar social context (i.e., their home cages), and defeated males displayed different amounts of time and submissive behaviours towards a known opponent than a novel intruder, whereas males in the neutral-encounter groups did not show such differences. In experiment 2, in an unfamiliar social context (i.e., a Y-maze), defeated males generated submissive behaviours and fear memory towards a known opponent that they re-encountered 5-min and 24-h after the defeat. The formation of long-term memory was interrupted by an injection of anisomycin (210 mg/kg). In experiment 3, in a non-social, anxiogenic context, hamsters that had previously had different social experiences did not demonstrate additional anxiety in an elevated plus-maze, with the exception of males that had previously experienced repeated social defeats. Our data suggested that hamsters' behavioural changes following defeat are context-dependent and stimulus-specific. The experience of a single social defeat is sufficient to regenerate submissive behaviours and fear memory when reencountering a known opponent.

Terminalia Arjuna (Roxb.) Modulates Circulatory Antioxidants on 7,12-dimethylbenz(a)anthracene- induced Hamster Buccal Pouch Carcinogenesis.

Oral cancer is the fifth most frequent cancer worldwide and India has recorded the highest incidence (40-50%) of oral malignancy. This study is designed to investigate the effect of aqueous extract of Terminalia arjuna bark (TaBet) on circulatory lipid peroxidation and antioxidant status during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Male Syrian golden hamsters painted with 0.5% 7,12-dimethylbenz[a]anthracene on the buccal pouches and developed oral squamous cell carcinoma were included in this study. The enhanced Thiobarbituric acid reactive substances in circulation of tumor-bearing animals was accompanied by a significant decrease in the levels of vitamin C, vitamin E, reduced glutathione, superoxide dismutase, catalase and glutathione peroxidase. Administration of TaBet (500 mg/kg body weight) significantly suppressed DMBA-induced hamster buccal pouch carcinomas, decreased lipid peroxidation and enhanced the levels of antioxidants. The chemopreventive potential of TaBet is probably due to its antilipidperoxidative effect or the presence of some potent bioactive chemopreventive principles in the bark of Terminalia arjuna. The results of the present study indicate that T. arjuna may emerge as a putative chemopreventive agent against oral carcinogenesis.

Trans-8,cis-10+cis-9,trans-11-conjugated linoleic acid mixture alters body composition in Syrian golden hamsters fed a hypercholesterolaemic diet

The effectiveness of conjugated linoleic acid (CLA) as a weight-loss nutraceutical continues to be debatable, suggesting that there may be value in exploring the physiological effects of the lesser-known isomers. The effects of the minor isomer, trans-8, cis-10 (t8, c10)-CLA, in the form of an equimolar mixture with the cis-9, trans-11 (c9, t11) isomer, on body weight and body composition, circulating glucose and lipid concentrations, and liver weights were studied in sixty male Syrian golden hamsters. Animals were randomised to receive for 28 d a semi-purified, hypercholesterolaemic diet (5% dietary fat and 0.25% cholesterol) supplemented at the 2% level with either the t8, c10+c9, t11-CLA mixture, c9, t11-CLA or trans-10, cis-12 (t10, c12)-CLA replacing lard and safflower-seed oil (control). Results show that compared with control, the t8, c10+c9, t11-CLA mixture and t10, c12-CLA-fed animals had lower (P < 0.0001) fat mass following supplementation. Animals consuming t10, c12-CLA also possessed higher lean mass compared with control and c9, t11-CLA groups (P < 0.001). However, the livers of these animals were larger (P < 0.0001) compared with those in the control and other CLA groups. Body weights of the hamsters did not differ across the experimental groups. CLA treatments had no effect on serum glucose or lipid profile, except for inducing higher (P < 0.05) non-HDL-cholesterol concentration with t10, c12-CLA compared with the c9, t11 isomer. Overall, these results indicate that in male hamsters fed a hypercholesterolaemic diet, the t8, c10+c9, t11-CLA mixture does not have an impact on blood lipid profile, but is able to effectively reduce fat mass, without incurring an accompanying liver enlargement.

521 Enhanced pulmonary tumourigenesis by N-nitrosobis (2-hydroxypropyl) amine after thoracic irradiation with X-rays in new born, juvenile and adult Wistar rats

Weekly application of N-nitrosobis (2-hydroxypropyl) amine (BHP) at a dose of 50 mg/application to the skin of the neck and flank organ of male Syrian golden hamsters induced no local lesions. However, nearly all treated animals developed internal tumors, primarily of pancreatic, hepatic, respiratory and colorectal origins. Results from this and previous studies indicate that the local carcinogenic effect of nitrosamines depends on the molecular structure of the carcinogen, rather than on tissue specificity. Furthermore, some common types of human cancer could be induced by absorption of specific nitrosamines through skin.

Efficacy of Diabetinol™ on glycemic control in insulin resistant hamsters and subjects with impaired fasting glucose – a pilot study

The anti-diabetic potential of Diabetinol™ was tested in an animal model and in a pilot study in humans. Male Syrian golden hamsters ( n = 18) were fed regular chow, 60% fructose or a 60% fructose diet + 1% Diabetinol™. Hamsters fed 60% fructose + 1% Diabetinol™ demonstrated a decrease in blood glucose, serum insulin, total cholesterol and triacylglycerol levels as compared to the fructose-fed animals. Efficacy of Diabetinol™ (2 × 525 mg/day) was investigated in a randomized, placebo-controlled, double-blind trial where subjects ( n = 19) with impaired fasting glucose (IFG) on either Diabetinol™ or placebo were presented with a standard oral glucose challenge. After 84 days of supplementation a significant reduction ( p < 0.01) in glucose intolerance, total cholesterol, LDL-cholesterol and decreasing trends in the HbA1c were observed in subjects supplemented with Diabetinol™. This study demonstrated an important future role for the Diabetinol™ in glycemic control and management of risk factors in subjects with IFG on oral medication.

Peanuts, Peanut Oil, and Fat Free Peanut Flour Reduced Cardiovascular Disease Risk Factors and the Development of Atherosclerosis in Syrian Golden Hamsters

Human clinical trials have demonstrated the cardiovascular protective properties of peanuts and peanut oil in decreasing total and low density lipoprotein cholesterol (LDL-C) without reducing high density lipoprotein cholesterol (HDL-C). The cardiovascular effects of the nonlipid portion of peanuts has not been evaluated even though that fraction contains arginine, flavonoids, folates, and other compounds that have been linked to cardiovascular health. The objective of this study was to evaluate the effects of fat free peanut flour (FFPF), peanuts, and peanut oil on cardiovascular disease (CVD) risk factors and the development of atherosclerosis in male Syrian golden hamsters. Each experimental diet group was fed a high fat, high cholesterol diet with various peanut components (FFPF, peanut oil, or peanuts) substituted for similar metabolic components in the control diet. Tissues were collected at week 0, 12, 18, and 24. Total plasma cholesterol (TPC), LDL-C, and HDL-C distributions were determined by high-performance gel filtration chromatography, while aortic total cholesterol (TC) and cholesteryl ester (CE) were determined by gas liquid chromatography. Peanuts, peanut oil, and FFPF diet groups had significantly (P < 0.05) lower TPC, non-HDL-C than the control group beginning at about 12 wk and continuing through the 24-wk study. HDL-C was not significantly different among the diet groups. Peanut and peanut component diets retarded an increase in TC and CE. Because CE is an indicator of the development of atherosclerosis this study demonstrated that peanuts, peanut oil, and FFPF retarded the development of atherosclerosis in animals consuming an atherosclerosis inducing diet.

Scent Marking by Male Golden Hamsters (Mesocricetus auratus)

Im Band 37, Heft 2, Seite 213, soll der erste Satz des Abstract wie folgt verbessert werden: 8 male golden hamsters were observed two at a time in a plexiglas cage (area roughly 11 sg. ft.) subdivided into 47 connected compartments. 8 malexj golden hamsters were observed two at a time in a plexiglas cage (area roughly 11 sp. ft.) subdivided into 47 connected compartments. Each pair spent 2–3 weeks in this cage, observations lasting 1–2 weeks. Dominance relationships, food hoarding and marking behaviour in this situation are described.

Cordycepin Prevents Hyperlipidemia in Hamsters Fed a High-Fat Diet via Activation of AMP-Activated Protein Kinase

Hyperlipidemia is a major risk factor for cardiovascular diseases. In this study, we investigated the potential effects of cordycepin (3′-deoxyadenosine), a bioactive component of the fungus Cordyceps militaris, on hyperlipidemia. We found that in male Syrian golden hamsters fed a high-fat diet (HFD), daily administration of cordycepin effectively reduced the accumulation of serum total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-c) and suppressed HFD-associated increases in relative retroperitoneal fat. It also increased the levels of phospho–AMP-activated protein kinase (AMPK) and phospho–acetyl-CoA carboxylase (phospho-ACC) in liver and retroperitoneal adipose tissues. In HepG2 cells, cordycepin stimulated robust concentration- and time-dependent AMPK activation that correlated with the activation of ACC and the suppression of lipid biosynthesis. However, pretreatment with compound C, a specific inhibitor of AMPK, substantially abolished the effects of cordycepin on AMPK activation and lipid biosynthesis inhibition. These results indicate that cordycepin prevents hyperlipidemia via activation of AMPK. Experiments on abnormal metabolic mice indicated that cordycepin can also improve insulin sensitivity effectively.

Promoting Effects of Sucrose-rich Diet on N-Nitrosobis (2-oxopropyl) amine-induced Pancreatic Carcinogenesis in Hamsters

It has been reported that there is an association between pancreatic cancer and obesity, impaired glucose metabolism and diabetes based on excess dietary fat and sugar intakes. A number of studies have suggested that a high-fat diet increases development of carcinomas in various organs and possible risk factors for pancreatic cancer. However, how an excess sugar intake promotes pancreatic carcinogenesis is still unknown. In the present study, we investigated the influence of an excess sugar intake on pancreatic carcinogenesis by administration of a sucrose-rich diet in which starch was replaced by sucrose in order to contain the same calories and other nutrients. Two similar experiments were performed. Six-week-old male Syrian golden hamsters were given N-nitrosobis (2-oxopropyl) amine (BOP) at a dose of 50 and 20 mg/kg body weight as a carcinogen in Week 0 and 1, respectively. In Week 2, the animals were divided into control and experimental groups. In experiment 1, 15 animals received a control diet or sucrose-rich diet in which 100% of the starch was replaced by sucrose, respectively. Since five animals fed on the sucrose-rich diet died by Week 12, the diet was changed to a sucrose-rich diet in which 50% of the starch was replaced by sucrose. In experiment 2, 15 animals received a control diet or sucrose-rich diet in which 50 or 20% of the starch was replaced by sucrose, respectively. All animals were sacrificed 25 weeks after the start of the experiment, and histological examination of the pancreas was performed. No significant difference was seen in the body weight at the end of the experiment. There were no significant differences in the glycosylated hemoglobin (HbA1c) and serum triglyceride, total cholesterol and HDL-cholesterol levels between the control and sucrose-rich diet groups in experiments 1 and 2. The incidence and number of carcinomas increased in hamsters fed the sucrose-rich diet compared with the control diet in experiments 1 and 2. These results suggest that an excess sucrose intake may promote the development of pancreatic cancer in hamsters.

Effect of Dexamethasone Premedication on Oral Mucositis in Hamster

Davarmanesh, M., Mardani, M., Mirkhani, H., Monabbati, A., Tanideh, N. and Mehrabani, D. 2009. Effect of dexamethasone premedication on oral mucositis in hamster. J. Appl. Anim. Res., 36: 267–270. To determine the protective effect of dexamethasone on the course of an experimental oral mucositis, 75 male adult golden hamsters were randomly divided into five equal groups. The control group received no medication. The other four groups received 5-fluorouracil on days 1–2, one hour after daily injections of either normal saline or dexamethasone in three doses and continued till d9. Along 16 d of experimental period to cover oral mucositis resolution, all animals were blindly subjected to scratching by needle tips over the cheek pouches on d 4 to potentiate oral mucositis. Macroscopic assessments were performed on d 6, 9, 16 and microscopic assessments in sacrificed animals on days 9 and 16 using a valid scoring systems and a blood sampling for microbiological culture in two randomly selected animals from each group (d 9). A significant protective role of dexamethasone was observed at high and moderate doses on the course of oral mucositis development. Our findings showed that in the course of the current chemotherapeutic regimens, premedication of dexamethasone could effectively intervene against development of oral mucositis.

Effects of Buflomedil and Pentoxifylline on Hamster Skin-Flap Microcirculation: Prediction of Flap Viability Using Orthogonal Polarization Spectral Imaging

OBJECTIVEThis study investigated the effects of buflomedil and pentoxifylline, both of which are used in reconstructive surgery of hamster skin flap microcirculation, and evaluated the skin flap survival rate by orthogonal polarization spectral imaging.METHODTwenty-four adult male Syrian golden hamsters were divided into three groups: a control (C, 0.1 ml 0.9% saline), buflomedil (B, 3 mg/kg/day), and pentoxifylline group (P, 14.5 mg/kg/day). Treatments administered intraperitoneally were initiated 1 hour before skin flap preparation and continued for 7 days post-operatively at 12-hour intervals. Preparations (skin flaps) were divided into 12 fields, which were organized into six bands. Functional capillary density (FCD, in mm/mm2), distance from the skin flap base to blood flow cessation (Distwith flow, in cm), percentage of viable skin (VA, in%), and qualitative analysis of blood flow by orthogonal polarization spectral imaging were performed at 1 and 24 hours and on the seventh post-operative day.RESULTBands IV, V, and VI presented no flow independent of time. The functional capillary density group B was higher than that of groups C and P, primarily after 24 hours. All groups showed an increase in D with time but reached similar final distances (C = 2.73, B = 2.78 and P = 2.70 cm). Moreover, the percentage of viable areas remained at approximately 50%. The orthogonal polarization spectral imaging was useful to assess viability by counting fields with and without blood flow.CONCLUSIONSFunctional capillary density values were higher in the buflomedil group compared to the control and pentoxifylline groups in this model. Functional capillary density did not influence D or the percentage of VA, and the technique showed favorable potential to assess/predict the viability of skin flaps within 1 h after surgery.

ERYTHROPOIETIN ENHANCES OXYGENATION IN CRITICALLY PERFUSED TISSUE THROUGH MODULATION OF NITRIC OXIDE SYNTHASE

The aim of this study was to investigate the effect of human recombinant erythropoietin (EPO) on the microcirculation and oxygenation of critically ischemic tissue and to elucidate the role of endothelial NO synthase in EPO-mediated tissue protection. Island flaps were dissected from the back skin of anesthetized male Syrian golden hamsters including a critically ischemic, hypoxic area that was perfused via a collateralized vasculature. Before ischemia, animals received an injection of epoetin beta at a dose of 5,000 U/kg body weight with (n = 7) or without (n = 7) blocking NO synthase by 30 mg/kg body weight L-NAME (Nomega-nitro-L-arginine methyl ester hydrochloride). Saline-treated animals served as control (n = 7). Ischemic tissue damage was characterized by severe hypoperfusion and inflammation, hypoxia, and accumulation of apoptotic cell nuclei after 5 h of collateralization. Erythropoietin pretreatment increased arteriolar and venular blood flow by 33% and 37%, respectively (P < 0.05), and attenuated leukocytic inflammation by approximately 75% (P < 0.05). Furthermore, partial tissue oxygen tension in the ischemic tissue increased from 8.2 to 15.8 mmHg (P < 0.05), which was paralleled by a 21% increased density of patent capillaries (P < 0.05) and a 50% reduced apoptotic cell count (P < 0.05). The improved microcirculation and oxygenation were associated with a 2.2-fold (P < 0.05) increase of endothelial NO synthase protein expression. Of interest, L-NAME completely abolished all the beneficial effects of EPO pretreatment. Our study demonstrates that, in critically ischemic and hypoxic collateralized tissue, EPO pretreatment improves tissue perfusion and oxygenation in vivo. This effect may be attributed to NO-dependent vasodilative effects and anti-inflammatory actions on the altered vascular endothelium.

Vasopressin facilitates play fighting in juvenile golden hamsters

Vasopressin facilitates aggression in adult hamsters. Whether this neuropeptide has a similar role in play fighting remains unknown. The goal of the present study was to identify whether vasopressin controls play fighting in juvenile golden hamsters as well. Juvenile male golden hamsters were tested for play fighting after microinjections of a vasopressin V1A-receptor antagonist, Manning compound, either 0, 9, or 90 µM, into the anterior hypothalamus. The treatment selectively inhibited offensive aspects of play fighting in experimental animals. Attack frequencies were significantly decreased by both doses of Manning compound. In addition, the high dose of the receptor antagonist increased attack latencies, decreased bite frequencies, and decreased the averaged number of attacks per contact bout. Together, these results show that vasopressin controls offensive behaviors throughout development from play fighting in juveniles to aggression in adults.

Innervation of accessory sex glands in the adult male golden hamster and quantitative changes of nerve densities with age.

Enzyme histochemistry and immunohistochemistry were used to determine the types of nerves supplying the ampullary gland, coagulating gland, dorsolateral prostate, ventral prostate and seminal vesicle of the male golden hamster. Quantitative change of dopamine beta-hydroxylase (DbetaH), and neuropeptide Y (NPY) immunoreactive and acetylcholinesterase-stained (AChE-stained) nerves with age was also determined. Using an antibody against protein gene product 9.5, nerves were seen to distribute in subepithelial connective tissues, smooth muscles and adventitial connective tissues. Presumptive catecholaminergic nerves immunoreactive for DbetaH and tyrosine hydroxylase were found mainly in periacinar smooth muscles, while AChE-stained nerves predominantly ramified subepithelial connective tissues. In addition, nerves immunoreactive to NPY, calcitonin gene-related peptide, leu-enkephalin, galanin, substance P, and vasoactive intestinal peptide were also detected. Quantitative estimation at 10, 52 and 78 weeks of age showed that densities of DbetaH and NPY nerves were halved by 52 weeks of age. This level was maintained in older animals. The density of AChE-stained nerves in all glands did not change with age. The ampullary gland appeared to have more AChE-stained nerves. These results were discussed from a comparative viewpoint and with regard to possible implications of aging of peripheral nerves on functioning of the male accessory sex glands.

Antifertility effects of sulfapyridine on male hamsters

Sulfapyridine was administered to mature male golden hamsters either by impregnation in feed pellets, or by subcutaneous injection as a solution in dimethylsulfoxide. The average litter size for control males was 8.3 +/- 3.3 (n = 13) vs. 4.2 +/- 2.7 (n = 11) for sulfapyridine-fed treated animals. Histology of the testis and epididymis was normal and sperm were normal in morphology and motility. Subcutaneous injection of sulfapyridine caused much more dramatic inhibition of male fertility than was achieved by feeding the drug. Sulfapyridine (750 mg/kg body weight in 0.2 ml DMSO) injected subcutaneously for 60 days was effective in reducing testis size and sperm quality. Histology of testes showed spermatogenic arrest at young spermatids. Two classes of animals were found in both sulfapyridine-fed and -injected treatment groups. One class was relatively resistant to the antifertility effects of the drugs. This difference may reflect differing abilities of the animals to convert sulfapyridine to an active form or to excrete its metabolites.