Effect of enrichment on stress level of laboratory rats

In certain biomedical research protocols, there is a need to singly house experimental rats. Since rodents are classified as social animals in nature, housing rats singly will result in stress to the animals. The aim of this study was to determine the effect of enrichment to the stress leukogram, feed intake, weight gain and behavior of singly-housed rats as opposed to singly-housed rats without enrichment and pair-housed rats. Eighteen 5 weeks old, male Sprague-Dawley rats were randomly assigned to three groups; singly-housed without enrichment, singly-housed with enrichment (provided with enrichment nestlets), and pair-housed. The rats were acclimatized for 7 days before start of study. Blood samplings were done on days 0, 14 and 26 for complete blood and differential counts. Feed intake and weight gain were recorded every 4 days and on days 0, 14 and 26. Behavioral assessment was done every week for 10 minutes for each cage. Results showed significant neutropenia in the singly-housed rats with and without enrichment as opposed to neutrophilia in the pair-housed rats. Monocytosis and eosinophilia were also more evident in the singly-housed rats without enrichment than in either the pair-housed rats or singly-housed rats with enrichment. However, there was no significant difference in other blood parameters, feed intake and weight gain. Singly-housed rats without enrichment also showed significantly higher stereotypical behavior when compared to rats in the other two groups. Thus, it could be concluded that singly-housed rats did not show higher stress level than pair-housed rats in the short term. Enrichment nestlets too have been proven to be effective in reducing some degree stress, aggression and stereotypical behavior in singly-housed rats

Seroprevalence of helicobacter hepaticus in mice from laboratary animal facilities in Klang Valley, Malaysia

Helicobacter is a genus of Gram-negativebacteria possessing a characteristic helix shape. They were initially considered to be members of the Campylobacter genus, but since 1989 they have been grouped in their own genus. Helicobacter hepaticusis an enterohepatic Helicobacter species (EHS) belonging to the family Helicobacteriaceae of the order Campylobacterales of Epsilon-proteobacteria division. It is a Gram-negative, microaerophilic, urease-positive, spiral rod. H. hepaticus colonises the colon and invades the liver of mice causing chronic severe active hepatitis and proliferative typhlocolitis. It can also induce hepatocellular carcinomas in certain breeds. The bacterium has been associated with inflammatory bowel disease in immunocompromised mice. Certain strains of mice will develop a proliferative, inflammatory typhlitis and/or colitis that may result in rectal prolapse. Detection of H. hepaticus in laboratory mice is therefore important because of its effect on research animals ultimately complicating the research findings. Currently PCR, culture, serology test or histologic examination of silver-stained liver sections is used to diagnose H. hepaticus infection. Most mice colonised with helicobacters remain asymptomatic for long periods of time. This study was conducted to investigate the serological prevalence of Helicobacter hepaticus in mice in 5 laboratory facilities in the Klang Valley. Fifty sera were collected and examined for presence of H. hepaticus antibodies by commercial ELISA test kit. Result showed two facilities had positive sera towards H. hepaticus while the rest were negative. Four of fifty sera were positive while other serum samples were negative

Effect of stocking density on Haematological indices and welfare of grower rabbits (Oryctolagus cuniculus) in tropical climate.

Ten New Zealand white cross rabbits of mixed sexes aged 10 weeks were used to evaluate the effect of stocking density (1 m2/rabbit and 0.1 m2/rabbit for 29 days) on haematological indices and welfare parameters in tropical climate. The rabbits were divided equally and allotted to the two stocking densities corresponding to an area of 0.5 m2 for Group A and 5 m2 for Group B. The rabbits were fed ad libitum with commercial rabbit grower pellets and fresh water was freely available throughout the study period. Each treatment group was also given carrot every Saturday and alfalfa hay every Monday evening as dietary enrichment. Group B rabbits had higher packed cell volume, haemoglobin concentration, mean corpuscular volume and mean corpuscular haemoglobin concentration and recorded a steeper rise of these indices over time when compared to Group A rabbits. Neutrophil/Lymphocyte ratio showed a correlation between social hierarchy and the availability of more space. Group A rabbits had higher weight gain and feed efficiency compared to that of Group B rabbits. However Group B rabbits recorded higher locomotor activity and Group A rabbits were observed to be utilizing the raised platform more. Both groups enjoyed the dietary enrichment exhibiting increased locomotor activity. The results of the study indicate that rabbits kept at 1 m2/rabbit had better haematological indices and locomotion activities compared to rabbits kept at 0.1 m2/rabbit in the tropical climate of Malaysia

Comparison of effect of sex hormone manipulation during neonatal period, on mRNA expression of Slc9a4, Nr3c2, Htr5b and Mas1 in hippocampus and frontal cortex of male and female rats.

It has long been known that spatial memory and the ability to navigate through space are sexually dimorphic traits among mammals, and numerous studies have shown that these traits can be altered by means of sex hormone manipulation. Hippocampus, the main organ involved in this kind of memory, has specific signature genes with high expression level compared to other regions of the brain. Based on their expression levels and the role that products of these genes can play in processes like signal transduction, mediation of hormone effects and long term potentiation, these genes can be considered as genes necessary for routine tasks of hippocampus. Male and female rat pups were injected with estradiol and testosterone respectively. at early stage of their lives to examine the effect of sex hormone manipulation on mRNA expression of Slc9a4, Nr3c2, Htr5b and Mas1 using comparative quantitative real-time polymerase chain reaction. The results showed that expressions of these genes are strongly influenced by sex hormones in both the frontal cortex and hippocampus, especially in male hippocampus, in which expression of all genes were up-regulated. Htr5b was the only gene that was affected only in the males. Expression of Mas1 was contrary to expectations, showed stronger changes in its expression in cortex than in hippocampus. Nr3c2 was down regulated in all samples but up regulated in male hippocampus, and Slc9a4 also showed a huge up-regulation in male hippocampus compared to other samples

Effect of local versus imported rodent diet on body weight and blood parameters of Sprague-Dawley rats.

This study was conducted to determine the effect of short-term (28 day) feeding of a local and two imported rodent diet on the body weight and blood profile of the Sprague-Dawley rats. Thirty female Sprague-Dawley rats aged between five to six weeks were placed in pairs in the polyethylene cages. Water and feed were given ad libitum. The rats were assigned to three groups where one group was fed the local diet; the second fed a United States of America diet and the third an Australian diet. The rats were weighed on days 0, 7, 14, 21 and 28 and the feed excess weighed every two days. From this study, it can be concluded that in short-term feeding, the body weight of Sprague-Dawley rat were affected by the type of diet. However, there was no significant difference between blood parameters of rats fed local and imported diet. This also holds true for the liver enzymes. However, there was a significant (p>0.05) difference in blood urea nitrogen (BUN) concentrations between these rats. The Australian diet produced less effect on BUN concentrations

Effect of short-term ingestion of the methanolic extract of mitragyna speciosa on sperm quality in mice

Mitragyna speciosa (MS) which is known as “Ketum” in Malaysia and “Kratom” in Thailand is a tropical plant indigenous to Southeast Asia. The leaves of MS have been used by natives of these countries for their opium-like effects and cocaine-like stimulant activities to overcome fatigue, enhance tolerance to hard work, prolong the duration of sexual intercouse and increase libido in males. However, no scientific studies have been carries out to assess the effects of MS consumption on the quality of sperm in animals or man. In this study, the effect of short-term ingestion of MS on the quality of sperm in mice was investigated. Forty mice were divided into 5 groups; 2 controls and 3 treatments. The negative control group received 0.9% sodium chloride (NaC1, 10 mL/ kg) while the positive control received clomiphene (25 mg/70 kg). the respective treatment groups received either 50, 100 and 200 mg/kg of MS extract. The drugs and extracts were administered orally once daily for 14. The results showed an increase in the number of sperms in groups treated with MS. The morbidity rates of the sperm in groups treated with MS were markedly lower than that of the control groups. In addition, marked deformity in the sperm in the form of swelling at the tail was observed in the groups treated with MS. In conclusion, mice treated with MS showed an increase in the number of sperm count in spite of defect in sperm morphology and reduced sperm motility

Pathogenicity of Leptospira icterohaemorrhagiae serovar Lai strain Langkawi in guinea pigs (Cavia porcellus)

A tourist was infected with a new strain of leptospires namely, Leptospira icterohemorrhagiae serovar Lai strain Langkawi, when he was on vacation in Langkawi, Malaysia. The leptospiral strain was successfully isolated from the patient in the Netherland. In this study, the bacteria were retrieved from Holland and inoculated into fifteen guinea pigs in Universiti Putra Malaysia (UPM) to determine its pathogenicity. The main clinical symptoms in the guinea pigs were decreased appetite and jaundice. Blood profile showed high neutrophil, lymphocyte, PCV, RBC, haemoglobin, leukocyte and thrombocyte counts. Besides that, enhancement of electrolytes such as sodium (Na), chloride (Cl), and potassium (K) was also noted. Biochemical examination showed an increase alkaline phosphatase (ALP), aspartate transaminase (AST) and bilirubin levels. Albumin, alanine transaminase (ALT), blood urea, total protein and creatinine were low values. Histopathological examination under haematoxylin and eosin staining showed evidence of haemorrhages, congestion and oedema in all organs, with inflammatory cell infiltration characterized by neutrophils, lymphocytes and macrophages. Hydropic degeneration and cell necrosis were also common in the findings. Leptospires were detected from Day 2 p.i by silver staining and transmission electron microscopy (TEM). Rise in antibody titre was seen as early as Day 5 p.i and leptospiral DNA was detected by PCR in the kidneys and liver on Day 3 and Day 5, respectively. The findings were indicative of leptospirosis. This study demonstrated that guinea pigs are a suitable animal model to illustrate the clinical symptoms and pathological changes seen following infection with Leptospira icterohaemorrhagiae serovar Lai strain Langkawi. In general, the symptoms and changes seen in leptospirosis are similar to viral infections and the information and data from this present study would help differentiate infection due to leptospires from that of viral infection. Leptospiral infection has often been misdiagnosed to be viral infection such as influenza and dengue which have similar signs and symptoms as leptospirosis

Comparison of clinical signs and mortality rate in murine models infected with herpes virus isolates from captive wildlife

Clinical signs, cellular infectivity and mortality rate of two closely related alpha-herpesvirus from a gaur (UPMV5/05) and a bear(UPMVI9/05) were studied in mice experimentally infected via the nasal route. The grade of viral infection was divided into low (103 and 104 pfu/ml), medium (105 and 106 pfu/ml) and high (107 pfu/ml). Clinically, all animals with the exception of controls, showed respiratory and neurological sign starting from 36 hpi. Although there were a number of differences in the onset time of clinical signs, these were not significant and the types of clinical signs shown were common. Nevertheless, there was a significant difference in the mortality rate, in which isolate UPMVI9/05 from a bear was more pathogenic (83%) than the gaurisolate, UPMV5/05(16.7%). These results strongly suggest that the consequences of host adaptation of herpesviruses may have been derived from interspecies transmission and underscore the need for extreme caution when managing wild or captive animals in close proximity to bovines

Vascular pathology associated with Leptospira icterohaemorrhagiae serovar Lai strain Langkawi infection in guinea pigs (Cavia porcellus)

Fifteen (15) guinea pigs were experimentally infected with Leptospira icterohemorrhagiae serovar Lai strain Langkawi, a new strain that was isolated from a human leptospirosis patient. Hematoxylin and Eosin ((H&E) staining showed haemorrhages, congestion and oedema in all internal organs examined (lungs, liver, spleen and kidneys) with inflammatory cell infiltration characterized by neutrophils, lymphocytes and macrophages. Hydropic degeneration and cell necrosis were also common in our findings. Leptospires were detected starting Day 2 p.i by silver staining and Transmission Electron Microscopy (TEM). Rise in antibody titres started on Day 5 p.i and leptospiral DNA was detected beginning Day 3 in the kidneys and Day 5 in the liver by Polymerase Chain Reaction (PCR) assay. The findings illustrated the pathogenesis of leptospirosis in guinea pigs which disclosed them as a suitable animal model for demonstration of clinical symptoms of leptospirosis and pathological changes after being infected with Leptospira icterohaemorrhagiae serovar Lai strain Langkawi, particularly pulmonary haemorrhages, a leading cause of mortality in human leptospirosis

Adulterated honey consumption can induce obesity, increase blood glucose level and demonstrate toxicity effects

The effects of adulterated honey consumption towards human health is not widely known; mainly due to lack of systematic and scientific studies and low public awareness. In this study, short-term and long-term effects of consumption on two brands of commercially honey are available in Malaysian market was investigated and compared to normal control (NC) rats and rats fed with natural pineapple honey (PH) using male Sprague dawley rats. Adulteration of honey used in the study was measured using physicochemical and antioxidant analyses and identified as adulterated honey A (FHA) and B (FHB). No toxicity effect was found for short-term consumption (14 days with one honey consumption). However, visible effects were observed after 16 weeks of study. Both FHA and FHB showed a significant increase (p>0.05) in cholesterol (48.6 ± 4.8 mmol/L, 46.5 ± 3.6 mmol/L), triglycerides (26 ± 1.2 mmol/L, 24.4 ± 1.8 mmol/L) and glucose (28.4 ± 2.5 mmol/L, 25 ± 2.6 mmol/L) level respectively. In contrast, rats from NC and PH groups have lower cholesterol (26.5 ± 4.4 mmol/L, 18.94 ± 3.6 mmol/L), triglycerides (17.5 ± 1.2 mmol/L, 13.5 ± 1.5 mmol/L) and glucose (6.4 ± 1.4 mmol/L, 8.0 ± 1.5 mmol/L) level, respectively. The most critical finding was in total five rats from both fake honey groups showed early mortality. This intensive study indicates long-term adulterated honey may harm to human health and required prompt actions from various authorities locally and internationally to avoid other consequences in the future