Obesity attenuates formalin-induced tonic pain in British Angora Rabbits.

Obesity is known to alter various physiological parameters including the pain sensitivity. There are conflicting reports on the pain sensitivity in obesity. In this context, the present study was aimed to investigate the tonic pain response in obese rabbit model. To achieve this aim, two groups of adult male British Angora rabbits were used. One of the groups was fed with standard rabbit chow and served as control. The other group was fed high fat diet (HFD) for 10 weeks to produce obesity. The standard formalin test was performed at the start and after 10 weeks of dietary regimen in both the groups. Timed behavioral responses (limping, elevation of paw, licking, biting, grooming etc.) were categorized and quantified with the help of standard pain rating scale. The total average pain rating score decreased significantly from 2.01 ± 0.02 to 1.47 ± 0.08 (P<0.05) in HFD group after 10 weeks of dietary regimen, whereas there was no change in the control group. A significant negative correlation was observed between body weight and pain rating score in HFD group of rabbits (P<0.05, r=–0.62). Results suggest that obesity attenuates the tonic pain responses induced by formalin in British Angora rabbits.

High fat diet induces obesity in British Angora Rabbit : A model for experimental obesity.

A reliable and cost-effective animal model for human obesity with its manifested disorders is yet to be established in the context of increased morbidity and mortality due to obesity and its related problems. Therefore, an attempt was made to produce obesity in locally available British Angora Rabbits (BAR) and examine the effect on metabolic and cardiovascular parameters. Adult male BARs weighing nearly 2 kg were randomly divided into two groups, one of the groups was fed with high fat diet (HFD) ad libitum for 10 weeks and the control group received standard normal rabbit chow for same period. Body weight, skinfold thickness, serum cholesterol, serum glucose and resting heart rate were measured before and after the dietary regimens. After 10 weeks, HFD group of rabbits demonstrated significant (P<0.05) increase in body weight (+24%) and skinfold thickness (+37%). The gain in body weight was positively correlated to skinfold thickness (r=0.61). Serum cholesterol, serum glucose and resting heart rate were also increased by 46%, 52% and 15%, respectively. Whereas no such increases in any of these parameters were observed in control group of rabbits. Our results suggest that obesity can be produced in BARs by feeding HFD. The obesity manifests with cardiovascular and metabolic changes. It is proposed that this may serve as a valid and reliable model of experimental obesity.

Decline in respiratory performance of Varanasi population in 22 years: a cross-sectional study.

Lung function tests were performed on apparently healthy, non-smoking male volunteers aged 16-50 years normally staying in Varanasi city area. The volunteers were divided into five groups according to their age (16-19 yr, 20-25 yr, 26-30 yr, 31-35 yr, 40-50 yr). Anthropometric determinants (height and weight) and respiratory performance (vital capacity and peak expiratory flow rate) were recorded in the year 1982 and 2004. No significant (P>0.05) difference in height, weight and body mass index was detected between the age matched groups in the year 1982 and 2004. The Vital capacity (VC) was measured in 483 and 387 volunteers in the year 1982 and 2004 respectively; peak expiratory flow rate (PEFR) was measured in 200 and 388 subjects in the year 1982 and 2004 respectively. Both VC and PEFR were found to be reduced in the year 2004 as compared to those measured in 1982 from the similar population matched for age groups. They were significantly (P<0.001) lower (20-23% less for VC and 4-14% less for PEFR) in the 20-30 years age group. There was also significant (P<0.05) decrease in PEFR for the population of 16-19 years age group studied in 2004 compared to that of 1982. Significant (P<0.001) deterioration in VC per meter of height was observed in the population above 20 years of age. The mean values of VC (ml/m height) ranging from 2119.27 +/- 316.64 (20-25 years age group) to 1923.29 +/- 225.43 (40-50 years age group) in 1982 have dropped to 1896.54 +/- 289.50 and 1593.64 +/- 419.36 for the respective age groups in 2004. Similarly, mean value of PEFR (L/ min) was found to be reduced from 523.67 +/- 64.69 in 1982 to 471.44 +/- 85.25 in 2004 for the same age groups of 20-25 years. Similar reduction was also recorded for 16-19 yr group and 26-30 yr group of population. Air-pollution and sedentary lifestyles in the population of this city may be probable reasons for the decline in respiratory performance.

Effect of streptozotocin-induced diabetes on growth and proteolytic activity of different muscles in rats.

Fibre and non-fibre components and proteolytic activity of fore- and hindlimb muscles with different fibre composition and functions were examined in streptozotocin-induced diabetic rats. From hindlimb, extensor digitorum longus (EDL), medial gastrocnemius (MG) and soleus (SOL) were selected to represent muscles rich in fast oxidative-glycolytic, fast glycolytic and slow oxidative fibres, respectively. The biceps brachii (BB) and extensor carpi radialis longus (ECRL), represented forelimb muscles having similar fibre composition but performing flexor and extensor functions respectively. Among the five muscles studied, all but SOL showed decrease in muscle weight and protein in diabetic rats indicating the atrophy of these muscles. Atrophy was greater in EDL and MG as compared to ECRL and BB. This differential atrophy could be negatively correlated to the percentage of slow oxidative fibres. Despite the loss of fibre mass in diabetic group, elevated fibre protein concentration was observed in BB (flexor) but not in ECRL (extensor). There was a significant reduction in non-fibre protein concentration with markedly enhanced alkaline proteolytic activity in EDL of diabetic rats. Non-protein solid concentration was also increased in EDL and MG. These observations showed that fast muscles are more susceptible to diabetes induced atrophic changes and diabetes affected various muscle components differently in muscles with different fibre composition and functions. Therefore, fibre composition and function of a muscle may be the factors in determining muscle growth in diabetes.

Protein energy ratio as a critical factor in determining growth & glycogen content of muscles in rats.

Effect of protein deficiency, which was produced in rats either by feeding low protein diet (8% protein) ad libitum (PD) or by restricting the amount of diet containing 15 per cent protein (protein calorie deficiency; PCD) on the growth in terms of muscle weight, length, cross-sectional area, protein and glycogen content was studied in extensor digitorum longus (EDL), medial gastrocnemius (MG) and plantaris (PL) muscles in rat. Because of decreased total calorie intake, PCD group exhibited higher value for protein/total calorie consumption. Excepting glycogen concentration, the retardation of growth in terms of all parameters studied was less in the PCD group. Glycogen concentration (mg/g muscle weight) in the PCD group was 3.0 +/- 0.3 in EDL and 2.6 +/- 0.3 in PL, whereas the values in PD group were 1.0 +/- 0.1 in EDL and 1.1 +/- 0.2 in PL respectively. This glycogen sparing effect was not evident in MG of PCD group possibly due to the greater number of glycolytic fibres. It is suggested that lesser retardation of growth of muscles and glycogen sparing effect in PCD group, could be due to altered metabolic changes resulting in enhanced gluconeogenesis.

Fatigue and contractile responses of rat hindlimb muscles following excessive dexamethasone administration.

Muscle weight, protein content and contractile performance (tetanic tension, fatigue and recovery) of extensor digitorum longus and soleus were investigated in rat following systemic administration of Dexamethasone (DX), 5 mg/kg/day for ten days. These animals showed marked reduction in food intake during the course of DX treatment. As a control, a group of food restricted (FR) rats receiving equal amount of food consumed by the DX treated rats was also studied along with the saline control group, to differentiate the effect of DX on muscle from that of dietary deficiency. There was a greater degree of atrophy (reduced muscle mass and protein content) of extensor digitorum longus in DX treated rats as compared to that of the FR rats. In-situ isometric tetanic tension per gram of muscle and per unit weight of protein was similar in both the muscles in the DX treated and the FR rats. There was increased fatiguability with reduced post fatigue recovery in both the muscles of DX treated rats as compared to the FR rats. The results indicate that besides atrophy of fast twitch muscles, DX increases the fatiguability and decreases the postfatigue recovery in both fast and slow muscles.