Effect of lesion of nucleus septal medialis on energy homeostasis in wistar rats.

Mesolimbic areas such as nucleus accumbens, amygdala and septal nuclei are known to influence food intake and body weight. However, the reports on gender difference in the neural regulation of obesity and energy homeostasis are incomplete. Therefore, the present study was conducted to assess the effect of lesions of nucleus septal medialis (NSM) and the gender difference of lesion on food intake (FI), body weight (BW), serum lipid profile, thyroid profile, glucose and insulin levels and glucoseinsulin ratio (GIR) in Wistar albino rats. Twenty-four rats were divided equally into control and experimental groups having 6 male and 6 female rats in each group. In the experimental group, bilateral electrolytic lesion of NSM was performed by stereotaxy and post-lesion parameters were recorded. In the control group, sham-lesions of NSM were produced. Following lesion, blood glucose and serum insulin levels were decreased and GIR was increased significantly in female rats, but not in male rats. It was concluded that NSM is involved in energy homeostasis, especially in female rats.

Role of ventromedial hypothalamus on energy homeostasis in albino rats: Effect of gender.

Various brain areas like the ventromedial hypothalamus (VMH) are known to influence food intake and body weight. Though obesity is more common in females, the reports on gender difference in the neural regulation of energy homeostasis are not adequate. Therefore, the present study was conducted to assess the gender difference in the effect of VMH lesion on food intake (FI), body weight (BW), serum lipid profile, thyroid profile, glucose and insulin levels and glucose-insulin ratio (GIR) in Wistar albino rats. Twenty-four Wistar albino rats were divided equally into control and experimental groups with 6 male and 6 female rats in each. In the experimental group, bilateral electrolytic lesion of VMH was performed by stereotaxy and post-lesion parameters were recorded. In the control group, VMH sham lesion was made. Male-female difference in each parameter was determined. Following VMH lesion, FI was increased (females, P<0.01) and BW (males, P<0.05) and GIR decreased in males (P<0.001), which was significantly correlated with BW. T3 was more significantly correlated with FI and BW in females (P<0.000 and P<0.001). Following VMH lesion, male rats exhibited significant weight gain in the absence of proportionate hyperphagia indicating that weight-gain was mainly metabolic in nature. Also, the male rats developed more susceptibility to insulin resistance. The female rats developed resistance to weight-gain inspite of hyperphagia, which could be due to the higher T3 level.

Study of sympathovagal imbalance by spectral analysis of heart rate variability in young prehypertensives.

Though prehypertension has recently been considered as a risk factor for cardiovascular accidents, the pathophysiological mechanism that causes the development of prehypertension in normotensive subjects has not been fully elucidated. Therefore, the present study was conducted to assess the sympathovagal imbalance in prehypertensives and normotensives by spectral analysis of heart rate variability (HRV) to understand the nature of change in autonomic balance in this dysfunction. Body mass index (BMI), waist-hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), rate-pressure product (RPP) and spectral indices of HRV such as total power (TP), normalized low frequency power (LFnu), normalized high frequency power (HFnu), ratio of low frequency power to high frequency power (LF-HF ratio), mean heart rate (mean RR), square root of the mean squared differences of successive normal to normal intervals; (RMSSD), the number of interval differences of successive NN intervals greater than 50 ms (NN50) and the proportion derived by dividing NN50 by the total number of NN intervals (pNN50) were assessed in two groups of young subjects: normotensives (n=68) and prehypertensives (n=66). Sympathovagal balance (SVB) was analyzed and correlated with BMI, WHR, BHR, BP and RPP in both the groups. It was observed that autonomic imbalance in prehypertensives was due to increase in both sympathetic activity and vagal inhibition. LF-HF ratio, the sensitive indicator of SVB was significantly correlated with BMI, WHR, BHR, BP and RPP in prehypertensive subjects. It was concluded that vagal inhibition might be important in the critical alteration of sympathovagal balance in the development of prehypertension in young normotensive subjects.

Association of albumin-globulin ratio with sympathovagal imbalance in pregnancy-induced hypertension.

The early prediction of pregnancy-induced hypertension (PIH) is based on the demonstration of increased sympathetic activity in early part of pregnancy. However, the mechanisms that increase sympathetic activity in PIH have not yet been fully elucidated. Therefore, in the present study we have investigated the link of albumin-globulin ratio (AGR) to sympathovagal imbalance in PIH patients. Spectral analysis of HRV was performed in three groups of subjects (Group I: normal pregnant women; Group II: pregnant women with risk factors for PIH, but did not develop PIH; Group III: pregnant women with risk factors and developed PIH) and their biochemical parameters including AGR were recorded. It was observed that LF-HF ratio, the most sensitive indicator of sympathovagal balance was significantly high (P<0.01) since early pregnancy in group III compared to other groups, which was considerably correlated with AGR in group III (PIH subjects). It was suggested that alteration in AGR could have direct contribution to the sympathovagal imbalance that plays a critical role in the genesis of PIH.

Pulmonary function test in traffic police personnel in Pondicherry.

Traffic policemen working in the busy traffic signal areas get exposed to the vehicular emissions for years together. The fumes, chemicals and particles present in the emission are reported to be damaging to the lung functions of these individuals. Since there were no data available on the PFT parameters of traffic police personnel of Pondicherry, this study was taken up to assess the effect of traffic air pollution on their pulmonary functions. PFT parameters were recorded in age- and BMI-matched 30 traffic police personnel (study group) and 30 general police personnel (control group) of male gender. As chronic smoking is known to be a critical factor in altering lung function, PFT parameters were compared between the smokers as well as nonsmokers of both the groups. In nonsmokers, there was significant decrease in VC (P<0.05), FEV1 (P<0.01), FEF-25 (P<0.05) and PIF (P<0.05) in study group compared to the control group. In smokers, there was significant decrease in VC (P<0.05), FEV1 (P<0.0001), PEF (P<0.0001), MVV (P<0.0001), FEF-25 (P<0.0001), and PIF (P<0.01) in study group compared to the control group. These changes indicate restriction to the lung expansion, obstruction and narrowing of the airways in traffic police personnel compared to the general police personnel. This may be due to exposure to vehicular pollution for several hours in a day for many years causing decreased functional capacity of the lungs and chronic smoking worsens the condition.

Gender difference in the effect of short-term calorie restriction on body weight and immunological parameters in albino rats.

In the present study, we have assessed the effect of gender on short-term calorie restriction influencing body weight and immunological parameters in albino rats. Adult albino rats (12 females, 12 males) were taken for the study and randomly divided into control and experimental groups of both the genders (n=6 in each). Following the recording of their basal 24 h food intake and body weight, rats of experimental groups were allowed to undergo food restriction (eat every alternate day) for 21 days, whereas control rats were allowed to eat normally. 7 days before the completion of food restriction, all animals were immunized and different immunological parameters such as: –log2 of anti-SRBC titer (Ab titer), liver weight/body weight ratio (LWBWR), spleen weight/body weight ratio (SWBWR), total globulin (Tg) and albumin/globulin ratio (AGR) were assessed. Following three weeks of intermittent calorie restriction, LWBWR was increased in both male (p<0.05) and female (p<0.001) experimental rats compared to their respective controls. Though the increase in SWBWR was not statistically significant in male rats, the increase was significant in female rats (p<0.05). The SRBC titer and total globulin concentration were increased significantly in both male (p<0.01) and female (p<0.001) experimental rats. The decrease AGR was more in female compared to male rats (p<0.01). The decrease in body weight following calorie restriction was significantly correlated with alteration in their immunological parameters. Short-term intermittent calorie restriction was found to facilitate immunity, especially in female rats, which promises future research on health promoting effects of calorie control.

Sympathovagal imbalance in thyroid dysfunctions in females: Correlation with thyroid profile, heart rate and blood pressure.

The aim of the study was to investigate the role of spectral analysis of heart rate variability (HRV) for assessing the type and degree of sympathovagal imbalance (SVI) and their link to cardiovascular morbidities in thyroid dysfunctions. Forty-five female subjects (15 control subjects and freshly diagnosed untreated 15 hypothyroid and 15 hyperthyroid patients) were recruited for the study. Thyroid profile, body mass index (BMI), basal heart rate (BHR), blood pressure (BP) and spectral indices of HRV (TP, LFnu, HFnu and LF-HF ratio, mean RR, SDNN and RMSSD) were assessed in all the three groups. LF-HF ratio was correlated with thyroid profile, BMI, BHR and BP. SVI was more prominent in hyperthyroid (P<0.001) compared to hypothyroid (P<0.05) subjects. LF-HF ratio was correlated with thyroid profile in both hypo and hyperthyroid subjects; but correlation with BHR and BP was significant only in hyperthyroidism. Though the SVI was found to be due to both vagal withdrawal and sympathetic activation, especially in hyperthyroidism, contribution by vagal inhibition was prominent. Vagal inhibition contributes significantly to SVI in thyroid dysfunctions, especially in hyperthyroidism. As the present study indicates poor cardiovascular health due to vagal inhibition in patients suffering from thyroid dysfunctions, attempt should be made to improve vagal tone especially in hyperthyroid subjects to attain a stable sympathovagal and cardiovascular homeostasis.

Effects of injection of serotonin into nucleus caudatus on food and water intake and body weight in albino rats.

Serotonin is known to inhibit food and water intake. However, the effect of its injection into nucleus caudatus on food and water intake is not known. In the present study, serotonin hydrochloride, buspirone (the serotonin 5-HT1A agonist) and ondensetron (the 5HT3 antagonist) were injected into nucleus caudatus through stereotaxically implanted cannulae in three different dosages (1, 2 and 5 microg) and their effects on 24 h food and water intake, and body weight were recorded. The injection of serotonin hydrochloride resulted in a dose- dependent decrease in food intake attaining maximum of 27.3% at 5 microg dose, whereas water intake and body weight were decreased 12% and 4.3% respectively only at the highest does. Buspirone elicited a dose dependent inhibition of food and water intake and body weight (22.3%, 19.8% and 5.1% respectively), whereas ondensetron elicited an increase in food and water intake (37.8% and 36.3% respectively) without significantly altering bodyweight. It was concluded that serotonin hydrochloride injected into nucleus caudatus inhibits food and water intake significantly. These effects are mediated via 5-HT1A and 5HT3 receptors. The effect of injections of 5-HT1A receptor agonist is more pronounced on water intake. The effect of injections of 5HT3 receptor antagonist is also more pronounced on water intake.

Alteration of ingestive behaviours by nucleus accumbens in normal and streptozotocin-induced diabetic rats.

Twenty-four hour basal food and water intakes were recorded in Wistar rats. Diabetes was produced in a group of rats by injecting streptozotocin (STZ, 75 mg/kg, b.w., IP) and their post-diabetic basal food and water intakes were recorded. Noradrenaline (2 microg) and dopamine (2 microg) were injected separately into the nucleus accumbens through the implanted cannula in non-diabetic and diabetic animals and their 24 hr food and water intakes were recorded. Food and water intakes were also recorded following bilateral electrolytic lesions of nucleus accumbens in both the groups of rats. In diabetic rats, basal food and water intakes were significantly increased in comparison to basal intakes of non-diabetic rats. Following injection of noradrenaline, a significant increase in water intake but not food intake was seen in non-diabetic rats, whereas food and water intakes remained unchanged in diabetic rats. Following injection of dopamine, a significant increase in food and water intakes was observed in non-diabetic rats, whereas dopamine-induced increase in food intake was absent in diabetic rats. The bilateral lesions of nucleus accumbens resulted in a significant inhibition of food and water intakes in non-diabetic rats, whereas inhibition of water intake without change in food intake observed in diabetic rats. However, no difference was observed in the pattern of change in water intake following lesions or dopamine injections between non-diabetic and diabetic rats, whereas difference was observed for food intake. The results suggest that nucleus accumbens activity changes for food intake, but not for water intake in diabetes.