Effect of experimental diabetes and vagotomy on gastric emptying in rats.

The present study was performed to evaluate the rate of whole stomach emptying (WSE) in streptozotocin (STZ) induced rat model of diabetes mellitus by assessing the effect of bilateral gastric vagotomy in control as well as in experimental animals. Our results revealed that delayed emptying of solid foods by the stomach is demonstrated within 5 days of induction of diabetes in rats. After bilateral vagotomy, the later stages of WSE slowed down because of the diabetic state, most probably due to the direct effect of diabetes on the gastric antrum.

Differences in active avoidance behaviour of hypoactive and hyperactive rats subjected to immobilisation stress.

Open field activity was studied in Wistar rats. Animals with low scores of ambulatory and rearing behaviours were grouped as hypoactive and those with high scores as hyperactive. Acquisition of active avoidance learning in a shuttle box was studied in the two groups. Hyperactive rats in contrast to hypoactive rats showed a better acquisition of avoidance learning. Learning was suppressed in both groups by domperidone, but was facilitated by immobilisation stress in the hypoactive group only. The two groups did not differ in the basal and stress evoked heart rates. These observations suggest that immobilisation stress favours enhancement of the dopaminergic related behaviour like avoidance learning in hypoactive rats.

Electrophysiological studies in children with paralytic poliomyelitis.

Ten healthy children (Group I), twenty children with acute spinal poliomyelitis (Group II and III) and twenty children of post-polio residual paralysis (Group IV) between the age group of 9 months to 4 years were the study subjects. The motor nerve conduction velocity (MNCV), standardized distal motor latency (SDML) and motor latency (M-RL) were similar in all the groups studied No H-reflex could be elicited in children with acute spinal poliomyelitis seen within one week of onset of paralysis (Group II). The H-max from 4-6 week group (III) improved with time in 9-12 month (Group IV) but did not attain the control (Group I) value. The H-reflex latency (H-RL) which was prolonged in Group III children returned back to normal value in children with residual paralysis (Group IV). The M-max which was significantly reduced in Group II children further decreased in Group III children before showing a significant rise in children with residual paralysis (Group IV). The M-max showed a significant correlation to duration of paralysis during the first week of onset of the disease process and with the muscle power assessed clinically in children with residual paralysis (Group IV). The H/M ratio of children with acute paralysis (Group III) was similar to control while that of residual paralysis was significantly lower in comparison to controls. However, the corrected H/M ratio of children with acute paralysis (Group III) and residual paralysis (Group IV) was significantly lower than the controls. There was significant increase in corrected H/M ratio in group IV children compared to group III.

Nucleus accumbens lesion does not affect schedule induced polydipsia.

Rats with lesion of nucleus accumbens were hypodipsic under free-feeding conditions. In schedule-induced polydipsia (SIP) tests conducted by reducing the rats to 70% of free-feeding body weight and delivering 60 mg bengal gram pellets on a fixed time 1-min schedule, nucleus accumbens lesions did not delay the acquisition or show a decrease in the maintenance of S.I.P.

Effect of different feeding schedules on food intake in caudate lesioned rats.

Inbred albino rats were exposed to different feeding schedules before and after caudate nucleus lesions. The animals show adaptation to the new patterns of food deprivation even after caudate nucleus lesions. However, the lesioned animals are not able to elevate their food intake or body weight to the prelesion levels. These findings suggest that feeding, satiety and body weight mechanisms are disturbed in the absence of intact caudate nucleus, possibly due to removal of nigro-striatal dopamine influence.

Primary taste discrimination in alloxan diabetic rats with restricted access to testant and water.

This study was conducted to assess the primary taste discrimination in 18 h water deprived control and alloxan diabetic rats for a period of 60 min duration by using two bottle choice paradigm. Different concentrations of sodium chloride, sucrose, urea and hydrochloric acid were used for salty, sweet, bitter and sour taste sensations respectively. Alloxan diabetic rats showed loss of discrimination for sucrose and urea solutions, increased sensitivity for low concentration of hydrochloric acid and no change in sodium chloride taste sensitivity.

Modulation of feeding and drinking by dopamine in caudate and accumbens nuclei in rats.

Injection of dopamine (DA) into accumbens and caudate nuclei facilitates a dose-dependent increase in food and water intake, whereas administration of spiperone (SP), a central D2-receptor antagonist suppresses DA-facilitated food and water intake. Bilateral lesions of nucleus accumbens and caudatus result in a sustained and significant decrease in food and water intake. The results suggest that DA is a neurotransmitter involved in feeding and drinking behavior in accumbens and caudate nuclei and this effect is mediated by central D2 receptors.

The effect of bilateral gastric vagotomy and histamine stimulation on parietal cell activity in streptozotocin induced diabetic rat model.

Disturbances in gastric secretions are commonly associated with diabetes mellitus and are usually attributed to autonomic neuropathy. Systematic documentation of the effects of experimental diabetes on parietal cell functions are not available. This study has been designed to evaluate the acid secretory status of the parietal cells in streptozotocin (STZ) induced rat model of diabetes mellitus by assessing the effect of bilateral gastric vagotomy and histamine administration on them. Results show that bilateral gastric vagotomy in the control rats as well as in experimental diabetes lowers the acid secreting capacity of the parietal cells. In the diabetic rats, however, vagotomy does not further decrease the gastric acid secretion. Histamine stimulation augments the acid secretory response in the controls but this rise is substantially prevented in the diabetic state. Histamine challenge following vagotomy in normal controls elicits a sharp rise in gastric acid secretion though not to the same extent as seen in rats with intact vagi. In the diabetic rats however, histamine fails to augment acid secretion after vagotomy. Diabetes is thus seen to severely impair the acid secretory response of the parietal cells and their responsiveness to histamine.

Effect of yoga training on reaction time, respiratory endurance and muscle strength.

There is evidence that the practice of yoga improves physical and mental performance. The present investigation was undertaken to study the effect of yoga training on visual and auditory reaction times (RTs), maximum expiratory pressure (MEP), maximum inspiratory pressure (MIP), 40 mmHg test, breath holding time after expiration (BHTexp), breath holding time after inspiration (BHTinsp), and hand grip strength (HGS). Twenty seven student volunteers were given yoga training for 12 weeks. There was a significant (P < 0.001) decrease in visual RT (from 270.0 +/- 6.20 (SE) to 224.81 +/- 5.76 ms) as well as auditory RT (from 194.18 +/- 6.00 to 157.33 +/- 4.85 ms). MEP increased from 92.61 +/- 9.04 to 126.46 +/- 10.75 mmHg, while MIP increased from 72.23 +/- 6.45 to 90.92 +/- 6.03 mmHg, both these changes being statistically significant (P < 0.05). 40 mmHg test and HGS increased significantly (P < 0.001) from 36.57 +/- 2.04 to 53.36 +/- 3.95 s and 13.78 +/- 0.58 to 16.67 +/- 0.49 kg respectively. BHTexp increased from 32.15 +/- 1.41 to 44.53 +/- 3.78s (P < 0.01) and BHTinsp increased from 63.69 +/- 5.38 to 89.07 +/- 9.61 s (P < 0.05). Our results show that yoga practice for 12 weeks results in significant reduction in visual and auditory RTs and significant increase in respiratory pressures, breath holding times and HGS.

Effects of undernutrition and sex difference on skeletal muscle function in young rats.

The effects of undernutrition and sex difference on skeletal muscle contractile characteristics were studied in young albino rats. The skeletal muscle (gastrocnemius) of 8 week old pups with only one-third normal food intake (undernourished group = UN group; n = 18), as compared to free fed pups (control group = cont. group; n = 16), showed prolongation of contraction time (23.6 +/- 1.0 Vs 20.9 +/- 0.8 msec, Mean +/- SE, P < 0.05) and relaxation time (31.5 +/- 1.8 Vs 22.9 +/- 1.1 msec, P < 0.001) and retention of contraction force and endurance time. In 18 week old rats the effects of sex difference in females (n = 10), as compared to males (n = 10) were prolongation of contraction time in gastrocnemius (32.2 +/- 1.5 Vs 27.8 +/- 1.5 msec, P < 0.05), less force production in gastrocnemius (668.9 +/- 48.0 Vs 895.4 +/- 93.3 g, P < 0.05) and extensor digitorum longus (20.1 +/- 3.3 Vs 29.9 +/- 2.5 g, P < 0.05) and shorter endurance time (160.8 +/- 10.2 Vs 187.2 +/- 7.1 sec, P < 0.05) in soleus. Thus, it is concluded that early undernutrition has prolonged the contraction and relaxation times of the skeletal muscles and the effect of sex difference in the early adulthood was different in different skeletal muscles.

Septal polydipsia in rats is a primary polydipsia not mediated by dopamine.

Bilateral lesions of nucleus septal lateralis resulted in a sustained and significant increase in water intake, without any change in food intake. Intracerebral injection of dopamine (DA) or of spiperone (a central D2-receptor antagonist) did not elicit any change in water or food intake. The polydipsia resulting from septal lesions is thus a primary polydipsia, which is independent of food intake, and is not mediated by neurotransmitter dopamine.

Modulation of daily water intake by dopamine in caudate and accumbens nuclei in rats.

Bilateral lesions of accumbens and caudate nuclei resulted in significant and sustained increase in water intake. Administration of different doses of dopamine (DA) into these nuclei facilitated a dose-dependent increase in 24-h water intake, whereas injection of spiperone following administration of DA inhibited DA-facilitated water intake in a dose-dependent manner. Conversely, administration of DA and spiperone did not elicit any change in water intake in septal nuclei; rather septal lesion facilitated the water intake. This suggests that the nucleus accumbens and nucleus caudatus act as facilitatory thirst areas and that DA is a possible dipsogenic neurotransmitter in these nuclei. This also suggests that the nucleus septal lateralis is a thirst-inhibiting centre where DA may not be involved in dipsogenesis.

Acute effects of experimental diabetes on skeletal muscle contractile functions.

The study was planned to explore the short term effects of experimental diabetes on the contractile characteristics of soleus and diaphragm. Experimental diabetes was induced in rats by streptozotocin (50 mg/kg, IP). On the 5th day, the isometric contractions were studied in soleus (in situ) and in diaphragm strip (in vitro). The soleus of the diabetic group showed similar twitch characteristics and tetanic tensions, decreased maximal relaxation rate (MRR; p < 0.01) and increased endurance time (ET; p < 0.05) as compared to the control group. The diaphragm of the diabetic group showed greater twitch tension (p < 0.05) and tetanic tension (p < 0.01), increased MRR (p < 0.02) and similar ET compared to the control group. It is concluded that the streptozotocin-induced diabetic state produces differential effects on the skeletal muscle contractile characteristics.

Effect of head-up tilting on systolic time intervals in normal young volunteers.

Systolic time intervals (STI) are sensitive indices of myocardial function. Passive tilting is a rapidly reversible and non-invasive method for inducing cardiovascular stress. The present work was conducted to study the effect of graded head-up tilt (HUT) on STI. 20 male medical students were subjected to 30 degrees, 60 degrees and 80 degrees HUT on a tilting table. ECG, phonocardiogram and carotid pulse were recorded simultaneously on Grass polygraph. Electromechanical systole (QS2), left ventricular ejection time (LVET), pre-ejection period (PEP), PEP/LEVT ratio, heart rate (HR) and corrected STI were determined immediately after and at 1, 2, 3, 4 and 5 min after each angle tilt. HUT produced a decrease in QS2 which was more pronounced at higher angle tilt. LVET decreased after 60 degrees and 80 degrees HUT. PEP and PEP/LVET ratio decreased after each angle tilt. These changes in STI can be explained on the basis of sympathetic stimulation-induced increase in the inotropic state of the heart.

A membrane-free plethysmograph for recording volume changes including microlitres.

A method of plethysmography which does not require an air/water tight chamber is described. The method is sensitive enough to record microlitre volumes/volume changes. Its application in two situations, viz. in experimental (artificial) edema and blood flow measurement in the human hand has been demonstrated.

Electrophysiological studies on human phrenic nerve & diaphragm.

To determine normal values for phrenic nerve stimulation, the phrenic nerve was stimulated transcutaneously in 22 healthy adolescent male volunteers. The phrenic latency, amplitude and duration of the evoked diaphragm action potential (EDAP) were noted. Maximum mouth inspiratory pressure (MMIP) and maximum ventilation volume (MVV) were also measured to evaluate the maximal strength of the diaphragm. No significant correlations were observed between EDAP and the parameters of diaphragm strength. The correlation coefficient between the amplitude-duration product of EDAP (integral EDAP) and MMIP was +0.15 and it was +0.29 between the integral EDAP and MVV.

Avoidance learning under hypo and hyperglycemia in rats.

Learning behaviour under different glycaemic conditions were studied in albino rats using an avoidance box. When insulin and glucose levels were low after fasting, animals showed delay in avoidance learning. But there was no change in acquisition of learning after hypoglacaemia induced by insulin. This difference in behaviour under hypoglycaemia of almost similar severity is possibly due to difference in its rate of induction and activation of counter regulatory neuro-endocrine mechanisms. Diabetic (alloxan) rats failed to improve learning. Besides, hyperglycemia, other factors like metabolic disturbances, cytotoxic effects of alloxan may have inhibited learning in this group. Hypo or hyperglycemia disturb the function of neuronal substrates responsible for learning and memory.

Effect of altered ventilations on human spinal and supra spinal reflexes.

The present study was aimed at evaluating the alterations in the human reflexes brought about by briefly altered ventilations. In 20 healthy young male volunteers, the H reflex and blink reflex were studied during normal ventilation, voluntary hypoventilation and voluntary hyperventilation. The latencies of these reflexes were compared. It was observed that the amount of altered ventilations used in the present study could not produce any significant change in these reflexes except in the case of the early response of the blink reflex.

Effects of central administration of insulin in normal and VMH (ventromedial hypothalamus) lesioned rats on food intake.

Central effects of insulin on 20 min. food intake were studied in rats. Insulin administration in the lateral ventricular cerebrospinal fluid (CSF) did not alter food intake in the intact or lesioned ventromedial hypothalamus (VMH) rats. Whereas, after insulin injection in VMH there was a decrease in food intake. In VMH lesioned rats, subcutaneous injection of insulin increased food intake.