Sexual dimorphism in the whole brain and brainstem morphometry in the African giant pouched rat (Cricetomys gambianus, Waterhouse 1840)

The study was conducted to evaluate the sexual dimorphism in the morphometric parameters of the whole brain and the brainstem in adult captive African giant pouched rats. Twenty-nine brain samples, comprising 15 females and 14 males, were utilized. Following brain extraction by standard procedures, the mean values of the weights, lengths, diameters, and volumes of the intact brains and the brainstem structures were compared in male and female rats using quantitative analytical statistical methods. The absolute brain weight obtained in the male was significantly higher (p < 0.01) than that of the female while the relative brain weight obtained in the female (0.636 &#177; 0.049%) was higher than that of the male rats (0.564 &#177; 0.032%), although the difference in the values was not statistically significant (p > 0.05). The lengths of the brain and myelencephalon, as well as the weights of the myelencephalon and mesencephalon, did not differ between the two sexes (p > 0.05). The weights and lengths of the pons did not differ between the two sexes (p > 0.05). There was a significant difference (p < 0.05) in the pyramidal length and a highly significant difference (p < 0.01) in the pyramidal width between the two sexes, with the male rats having higher values. This pioneering sexual dimorphic brain morphometry provides information for further research. (Folia Morphol 2010; 69, 2: 69-74

Effects of continuous light exposure on testicular structure and function of the African giant rat (Cricetomys gambianus)

The aim of this investigation was to study the effects of continuous lighting exposure on the testes of the African giant rats (AGR). Samples of testes from twelve (12) healthy AGR were investigated under two groups. The rats were divided into two groups of 6 rats each as follows: Group I - Control rats (12 h light/12 h darkness); Group II - Rats exposed to continuous light (24 h). The indices of the testes were length, width, and weight of the organ, estimation of serum levels of testosterone, luteinizing hormones, follicle stimulating hormone (FSH) by radioimmunoassay (RIA) technique and histological studies of the testes. The mean body weight of the rats exposed to continuous light was 1.086 ± 0.034 kg which was reduced by 3.9 % from the control (1.131 ± 0.02 kg). The mean weight of the testes in rats, exposed to continuous light was 4.549 ± 0.30 g, which was significantly reduced by 17.8 %, when compared to the control (5.534 ± 0.16 g). The mean length and width of testes of rats exposed to continuous lighting was 0.294 ± 0.71 cm and 0.143 ± 0.48 cm, respectively. The mean serum level of testosterone in control rats was 1.225 ± 0.08 miu/ml and that in rats exposed to lighting, 0.275 ± 0.10 miu/ml. This result showed that the serum level of testosterone in male rats exposed to continuous lighting was reduced by 77.6 % from 1.225 ± 0.08 miu/ml in the control rats to 0.275 ± 0.10 miu/ml. Histological observations showed that the testes of rats exposed to light displayed elongated to round seminiferous tubules each with wide lumen lined by low germinal epithelium, and had wide interstitial spaces. Disruption of spermatogenesis and vacuolization of epithelial cells were evident. This study has shown that exposure of AGR for four (4) weeks of continuous lighting will result in disruption of spermatogenesis and decreased testosterone serum level.Keywords: Light; Testes; African giant ra

Effect of ketamine hydrochloride induced anaesthesia on Psammophis sibilans

This study sought to determine the actual dose of ketamine hydrochloride to be used to achieve surgical plane of anaesthesia in hissing sand snake (Psammophis sibilans). Ketamine hydrochloride was administered intravenously to the snakes at different doses based on their body weight, and some physiological parameters were monitored. Twelve snakes divided into four groups A, B, C and D were administered ketamine hydrochloride intravenously at 60 mg/kg, 46 mg/kg, 40 mg/kg, and 30 mg/kg respectively. With 40 mg/kg, a good plane of surgical anaesthesia was achieved in this species of snakes. The dose was able to achieve both anaesthesia and analgesia. Other dose recommended for anaesthesia was 30 mg/kg. It is concluded that dose higher than 46 mg/kg may cause the death of the animal. These result shows that ketamine hydrochloride is generally effective at 40 mg/kg in the Psammophis sibilans, with no wide individual variation in the time to onset (3.5±0.7 mins), duration of anaesthesia (23.5±9.19 mins), and time to recovery (36.5±25.1 mins).Keywords: Ketamine hydrochloride, Psammophis sibilans, righting reflex, anaesthesi

Elevated extracellular potassium ion concentrations suppress hippocampal oscillations in a mouse model of Dravet syndrome in-vitro

Background: Hippocampal hyperexcitability and seizure-like events have been consistently demonstrated in hippocampal slice preparations perfused with ≥ 5 mM high [K+] artificial cerebrospinal fluid (ACSF). Accordingly, high [K+] ACSF has been effectively employed as ionic model of seizure for in vitro experiments, but then, how reliable is this model when employed for in-vitro studies of brain tissues with dysregulated K+ homeostasis? To address this question, we examined how elevations of [K+]o affect hippocampal oscillations in Scn1a mutant mouse, a mouse model of Dravet syndrome, a devastating genetic-epilepsy associated with gliosis, a major cause of dysregulated K+ homeostasis in epileptic brain.Methods: To this end, performing local field potential (LFP) recordings from hippocampi of P30 to P38 Scn1a mutant mice (Scn1a +/-) and wild-type littermates (Scn1a +/+), maintained on a C57BL/6 genetic background, in brain slice preparations in normal and high K+ conditions, we studied the effect of 4 mM and 5 mM high [K+] ACSF(s) on hippocampal oscillations.Results: Hippocampal hyperexcitability was observed only in Scn1a +/+ but not in Scn1a +/- mice. In Scn1a +/- mice, spontaneous hippocampal hyperexcitability was observed in normal ACSF but was significantly suppressed by 4 mM and 5 mM high [K+] ACSF(s).Conclusion: In conclusion, these findings, for the first time, provide evidence of spontaneous hippocampal activity in Scn1a+/- mice older than P30 which may be potentially used as a target for screening anti-epileptic approaches, beneficial for the treatment of DS. Elevated [K+]o-induced depolarization block of neuronal action potentials is involved in epileptic brain tissues modulated in elevated [K+]o. This mechanism underlies the suppressing effect of high [K+] ACSF on hippocampal oscillations in Scn1a+/- mice in vitro. Future studies employing the high K+ ionic model for studies of epileptic brain tissues are required to determine how K+ homeostasis is handled by neurons and glial cells in epileptic brain tissues.Keywords: Dravet syndrome, artificial cerebrospinal fluid (ACSF), Scn1a mutant mouse, depolarization bloc

Resveratrol protects rabbits against cholesterol diet- induced hyperlipidaemia

The excessive consumption of high cholesterol diet has been associated with an increased incidence of lipidaemia. Lipidaemia is enhanced by formation of oxidative stress, lipid peroxidation and hyperglycaemia. The aim of these experiments was to investigate the protective effect of resveratrol co-administered with cholesterol diet induced hyperlipidaemia in rabbits. Thirty rabbits divided into six groups of five animal (group= 5) each: group 1 = normal control, group 2 = cholesterol diet/high fat diet group only (HFD), group 3 = resveratrol 200 mg/kg (R200), group 4 = resveratrol 400 mg/kg (R400), group 5 = HFD + R200 and group 6 = HFD + R400. The normal group was fed with standard animal feeds only; while the HFD groups were fed with standard animal feeds + cholesterol diet (10% Groundnut oil, 20% Groundnut mill and 2% cholesterol). Resveratrol-treated rabbits received resveratrol suspended in 10 g/L carboxymethylcellulose (CMC) and the control group received the vehicle only, CMC. The preparations were administered for 8 weeks of experimental protocol. At the end of the study period, the animals were sacrificed. Blood and plasma samples were collected. Serum evaluation of lipid profile such as total cholesterol (TC), triacylglycerol (Tg), low density lipoprotein cholesterol (LDP-c) and high density lipoprotein cholesterol (HDL-c) were also assessed. The results obtained show significant (P &lt; 0.05) decrease in total cholesterol (TC), Low density lipoprotein cholesterol (LDP-c), total triacylglycerol and an increase in high density lipoprotein cholesterol (HDL-c) in resveratrol treated groups compared to HFD group only. In conclusion, the findings indicated that Resveratrol may contain polar products able to lower plasma lipid concentrations and might be beneficial in treatment of hyperlipidemia and atherosclerosis.Keywords: Cholesterol diet, Lipidaemia, Rabbit; Resveratrol, LDL-c, HDL-c, TC, T

Pattern of Helicobacter pylori infection in normal, overweight and obese adults in Nigeria

Background: Obesity is a state of chronic energy imbalance which has a multifactorial origin, but mainly believed to be due to overeating and underactivity. Prevalence of obesity is rising to an epidemic level world-wide. Obesity is associated with metabolic and cardiovascular complications, and recently, Helicobacter pylori infection (H. pylori). H. pylori is a gram-negative bacteria that colonizes the gastric mucosa, and is highly prevalent. It has been implicated in the pathogenesis of chronic gastritis, gastric cancer and inflammation. Previous studies observed H. pylori infection as a risk factor to development of obesity, but other reports suggest a protective role of H. pylori against obesity. There is inconsistent data across various population studies.Aim: To investigate the pattern of H. pylori in overweight and obese subjects in Nigeria.Methods: A total of 277 subjects (185 males and 92 females), within the age of 18- 72 years were recruited from a university in northern part of Nigeria. Anthropometric and blood pressure were measured, and participants were grouped into normal, overweight and obese. H. pylori was serologically assayed by ELISA.Results: A total of 149 (53.8%) subjects were within normal body mass index (BMI), 55 (19.9%) were overweight and 73 (26.4%) were obese. From a total of 125 respondents who were positive to H. pylori, 52% were within normal group, 19.2% were overweight, and 28.8% were obese. H. pylori infection was present in 64/185 (34.6%) of males and 61/92 (66.3%) of females in the studied population. Out of obese respondents, only 16% of obese males were positive to H. pylori, but up to 43% of obese females were H. pylori positive.Conclusion: In the present study, H. pylori infection was less in obese males and more in the normal group. In the females, H. pylori was more in the obese and less in normal and overweight groups.Keywords: Helicobacter pylori, Overweight, Obese, Male, Females; Nigeri

Molecular mechanisms of aluminium neurotoxicity in animal models of Alzheimer’s disease

Alzheimer’s disease (AD) is the most common cause of dementia that affects one patient every seven seconds. With over 35 million people currently affected worldwide, it has been projected that the disease will affect about 115 million people by 2050. The disease is characterized by dysfunctional cellular and molecular networks and/or genomic and epigenomic interactions that affect the normal function of brain cells, leading to a defective cellular communication and function, and ultimately neurodegeneration. Aluminium (Al3+) is the third most abundant ubiquitous element in the earth crust which has gained easy access to humans and extensively used in daily life. It is an essential component of many materials used in households, such as clays, glasses, and alum. An increasing body of evidence implicates Al3+ in the progression of events that lead to neurodegenerative diseases, some of which remains controversial, but it is widely accepted that Al3+ is a recognised neurotoxin that could cause neurodegenerative diseases such as AD. The pathophysiological changes induced in Al3+ neurotoxicity leading to AD result in critical impairments of the central nervous system functions, which are essential for healthy brain ageing. These changes include; axonal transport, neurotransmitter synthesis and synaptic transmission, disruption of calcium homeostasis, alteration of energy metabolism, phosphorylation/dephosphorylation of proteins, protein degradation, gene expression, formation of reactive oxygen species and inflammatory responses, inhibition of DNA repair system, activation of glial cells, reduction of activities of antioxidant enzymes, alterations of pathways of NF-kB and JNK, binding DNA, cell death, motor and cognitive decline. These multi-faceted pathways provide a link between Al neurotoxicity and AD by modulating both tau and amyloid beta hypotheses of AD.Keywords: Alzheimer’s disease, Aluminium chloride, Amyloid beta, Tau, Animal model

Sub-acute insulin therapy does not affect long-term visiospatial learning and memory in mice assessed using Barnes maze

Insulin is a common hypoglycaemic agent used to treat diabetes, but it has also been reported to exert other effects on the body including modulation cognition. Reported findings on insulin effect on learning and memory are scanty and often conflicting. This study was aimed at evaluating the effect of sub-acute insulin therapy on visio-spatial learning and memory using Barnes maze. Twelve young mice of both sexes, weighing between 20 – 22 g, were divided into control and insulin-treated groups (n = 6). They were administered subcutaneously with deionized water (control) or insulin (10 I.U./kg/day) for seven days. During the last three days of treatments, the mice were subjected to two-day training and one-day probe trial of Barnes maze. Number of primary head searches on day 2 was reduced compared to day 1 for both the insulin-treated (4.17 ± 0.8 s and 11.45 ± 1.9 s) and control (10.0 ± 3.2 s and 19.95 ± 4.5 s) groups (P &lt; 0.05), but the values obtained in the two groups did not differ (P &gt; 0.05). Similarly, there was no difference between the insulin-treated and control groups in latency to locate the escape hole, time spent and number of head searches per quadrant. It was concluded that sub-acute insulin therapy did not affect long-term visio-spatial learning and memory in mice.Keywords: insulin, visio-spatial learning and memory, long-term memory, Barnes maze, mic

Biometric and morphologic studies of the female reproductive organs of the African giant rat (Cricetomys gambianus: Waterhouse)

Different segments of the reproductive tract of 100 adult, non-pregnant, female African giant rats (AGR) were carefully examined, weighed, and measured. The ovaries were observed to be small, pinkish, and kidney-shaped. The uterus of the AGR was found to be uterus duplex. The live weight of the AGR was 999.7 &#177; 16.86 g. The weight, length, and width of the ovary were 0.095 &#177; 0.003 g, 0.750 &#177; 0.01 cm, and 0.01&#177; 0.02 cm, respectively. The length of the oviduct, uterus, and vagina/vestibule were 4.44 &#177; 0.06 cm, 4.877 &#177; 0.11 cm, and 4.345 &#177; 0.07 cm, respectively. The weight and length of the entire tubular organs were 3.171 &#177; 0.01 g and 13.559 &#177; 0.18 cm with corresponding range values of 1.61&#8211;7.10 g and 7.80&#8211;17.40 cm, respectively. (Folia Morphol 2010; 69, 4: 213-215

Effects of selenium yeast on blood glucose and antioxidant biomarkers in cholesterol fed diet induced Type 2 diabetes mellitus in wistar rats

Selenium is an antioxidant that prevents oxygen radical from damaging cells from chronic diseases that can develop from cell injury and inflammation such as diabetes mellitus. The aim of the study is to investigate the possible protective effect of selenium yeast on cholesterol diet induced type-2 diabetes mellitus and oxidative stress in rats. Twenty male wistar rats were divided in to four groups of five animals each: Group 1: (Negative control) received standard animal feed only, Group 2: received cholesterol diet (CD) only, Group 3: received CD and 0.1 mg/kg selenium yeast orally, Group 4: Received CD and 0.2 mg/kg selenium yeast orally for six weeks. At the end of the study period, the animals were sacrificed and the serum samples were collected and evaluated for estimation of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). The results showed a significant (P &lt; 0.05) decrease in blood glucose level in the groups co-administered CD and selenium yeast when compared to CD group only. Antioxidant enzymes status recorded significant (P &lt; 0.05) decrease in SOD, CAT and GPx activities in CD and selenium yeast administered when compared to CD group only. In Conclusion, Selenium yeast administrations prevent free radical formations which are potent inducer of diabetes mellitus.Keywords: Cholesterol diet; Diabetes Mellitus; Selenium yeast; SOD; CAT; GP