Nociception, antinociceptive potency of morphine in streptozotocin induced diabetic rats.

There are controversial reports on the effect of diabetes on the pain threshold. We used male Wistar rats to see the effect of streptozotocin induced diabetes on the tail flick, vocalisation and vocalisation after discharge responses. These represent the spinal, lower brain stem and hypothalamic responses respectively. The effect of morphine in these parameters was studied for both the control and diabetic group. In diabetic rats, the pain threshold was increased. However, this increase was not significant. Morphine produced significant analgesia after thirty minutes for tail flick and vocalisation responses and after fifteen minutes for after discharge in the control group. The antinociceptive effect of morphine was delayed and reduced for all three pain threshold confirming the antagonistic action of glucose on opiate receptors.

Immobilisation stress induced analgesia in diabetic rats.

Stress is known to produce analgesia. The pain threshold is altered in diabetes. We studied the effect of 1 hr of immobilisation stress on pain threshold in male Wistar rats. The same effect was tested in streptozotocin induced diabetic rats. The pain threshold of tail flick, vocalisation and vocalisation after discharge increased in the control group after the stress procedure. Significant analgesia was also obtained in diabetic rats, for flick and after discharge pain threshold. However the vocalisation threshold was not altered, probably due to the antagonistic action of glucose on opiate receptor at the level of brain stem.

Hypotensive effect of intracerebroventricular injection of norepinephrine and its modulation by alpha and beta adrenergic blockers in conscious rabbits.

The present study was designed to investigate the role of central adrenoceptors in the hypotensive effect of intracerebroventricular (ICV) injection of norepinephrine (NE) in conscious rabbits. Experiments were carried out on 19 adult rabbits (oryctolagus cuniculus) of either sex. A dose-dependent hypotensive response to ICV injection of NE was observed with no significant change in heart rate. The hypotensive response of NE was blocked 74.2 +/- 0.7% by yohimbine (alpha-2 adrenergic blocker), and 25.0 +/- 0.5% by metoprolol (beta-1 adrenergic blocker). NE response was not affected either by prazosin or butoxamine (alpha-1 and beta-2 adrenergic blockers respectively). The results suggest that the dose-dependent hypotensive response of ICV administered NE is mediated through alpha-2 and beta-1 central adrenoceptors.

Brain cholesterol and phospholipid levels in cyproheptadine treated albino rats.

Effect of different doses (2.5 mg, 5 mg, 10 mg and 40 mg/kg), s.c., for 2 weeks, of cyproheptadine (CYP) on brain cholesterol and phospholipid of albino rats was investigated. Cyp. 2.5 mg/kg, showed increase in brain cholesterol and phospholipid contents whereas other doses caused a decrease in phospholipid level.

Autonomic functions during different phases of menstrual cycle.

Autonomic functions were studied in female healthy human subjects during the pre-menstrual, menstrual and post-menstrual phases. Our findings indicate a higher BP (systolic) and lower GSR in pre-menstrual phase as compared to other phases. Parasympathetic activity on the other hand does not show significant differences.

Effect of exercise on pulmonary function tests in normal first degree relations of asthmatic subjects.

The prevalence of exercise-induced asthma (EIA) after six minutes of standard exercise test on bicycle ergometer was studied in thirty healthy first degree relations of asthmatic subjects (group II) and was compared with that in thirty healthy controls (group I). Pulmonary function tests (PFT) measuring FVC, FEV1, FEF25-75% and PEFR were performed on each subject prior of exercise, immediately following exercise period and serially at 5 minute interval for 25 minutes thereafter. Bronchial lability was noted in 7% and 27% of the subjects in groups I and II respectively. Of all the parameters measured, FEF25-75% exhibited most striking changes when expressed as % of the baseline value.

Hypothalamic adrenoceptors concerned with control of temperature, elicited by chemical stimulation.

Norepinephrine (NE) and its blockers (alpha-1, alpha-2, beta-1 and beta-2) were micro-injected into the anterior hypothalamus of male albino rats and the effects of these injections on rectal temperature were recorded. The results indicated that the thermoregulatory effects of NE were dependent on ambient temperature. The present study further demonstrated the specific involvement of beta-2 receptors present in the anterior hypothalamus concerned with thermoregulation.

Effect of cyproheptadine on glucose tolerance, serum insulin and structure of pancreatic islets in rats.

The effect of cyproheptadine (CPH) on glucose tolerance, serum immunoreactive insulin (IRI) and structure of pancreatic islets in albino rats has been studied. Hyperglycemia with glucose intolerance was observed after 10 days of administration of CPH (40 mg/kg, ip). There was insignificant change of fasting IRI after the treatment. Histological studies indicated degranulation and vacuolation of beta cells with enlargement of capillaries. Improvement in blood glucose, glucose tolerance and structure of islets with proliferation of small pancreatic ducts and cell cords were observed 10 days after the withdrawal of CPH.

Centrally mediated alpha & beta adrenoceptors controlling blood pressure in rabbits.

The effect of intracerebroventricular (icv) injection of noradrenaline (NA) on the blood pressure was studied in anaesthetised rabbits. Adrenoceptor blockers were used to study the specific adrenoceptor mediating the response. The results indicated a hypotensive response to icv injection of NA. This hypotensive response to NA was blocked by alpha-2 (yohimbine) and beta-1 (metoprolol) but not by alpha-1 (prazosin) and beta-2 (butoxamine) adrenoceptor blockers.

A study of action of norepinephrine on hypothalamic feeding centres.

Effects of intrahypothalamic and intraventricular microinjections of norepinephrine (NE) were studied in fasted albino rats. Applications of NE into ventromedial hypothalamus (VMH), medial part of lateral hypothalamus (LH) and lateral ventricle (LV) caused marked but short lasting decrease in food intake, whereas lateral part of LH was insensitive to NE administration. Decrease in water intake seemed secondary to decrease in food intake. Decrease in food intake could not be attributed to the alteration of body temperature. This study explains the mechanism of anorexigenic action of amphetamine and the mechanism of hyperphagia following destruction of the ventral noradrenergic bundle.

Effect of adrenergic and cholinergic antagonists on post-hemorrhagic erythropoiesis in rats.

Experiments were carried out in albino rats to find out the effect of propranolol, priscol and atropine on post-hemorrhagic erythropoiesis. Administration of either propranolol or priscol decreased reticulocyte response following hemorrhage, whereas administration of atropine produced no change. The results indicate that alpha as well as beta adrenergic systems participate in the control of erythropoiesis following hemorrhage, whereas parasympathetic system does not take part.

The standardized distal motor latencies and the peak to peak amplitudes of evoked muscle action potentials in the extremities of humans.

The values of Standardized Distal Motor Latency (SDML) of Median, Ulnar and Common Peroneal nerves and the peak to peak amplitude of Evoked Muscle Action Potentials (EMAP) of the small muscles of the limbs were studied in 50 normal subjects. The SDML values showed significant sex difference, whereas no sex difference was observed in the amplitude of the EMAPs.

Effect of posture on heart rate and cardiac axis of mice.

Effect of change in body posture on cardiac electrical axis has not been well documented. Hence the present work was undertaken to study the effect of passive head-up and head-down postures on ventricular QRS axis and heart rate of anesthetised mice. During head-up posture, there was a statistically significant (P less than 0.02) increase in heart rate whereas during head-down posture, the heart rate decreased insignificantly. These changes in heart rate can be explained on the basis of synus and aortic nerve mediated baroreceptor reflexes. Ventricular QRS axis showed a significant increase (P less than 0.02) during head-up posture and an insignificant decrease during head-down posture. A change in the posture is likely to produce a change in anatomical orientation of heart within the thorax resulting in alteration of electrical axis of the heart.

Effect of yoga type breathing on heart rate and cardiac axis of normal subjects.

Effect of inspiratory and expiratory phases of normal quiet breathing, deep breathing and savitri pranayam type breathing on heart rate and mean ventricular QRS axis was investigated in young, healthy untrained subjects. Pranayam type breathing produced significant cardioacceleration and increase in QRS axis during the inspiratory phase as compared to eupnea. On the other hand, expiratory effort during pranayam type breathing did not produce any significant change in heart rate or QRS axis. The changes in heart rate and QRS axis during the inspiratory and expiratory phases of pranayam type breathing were similar to the changes observed during the corresponding phases of deep breathing.

Acute effect of streptozotocin induced diabetes on bar pressing for food reward in albino rats.

The operant behaviour in streptozotocin (45 mg or 65 mg/kg) treated rats was studied using albino rats of either sex. Animals were trained daily for 15 days in an operant chamber (Takei & Co.) to press the bar for getting the reward in the form of 45 mg food pellet following 18 hr of food deprivation. After initial training under continuous reinforcement schedule (CRF), animals were trained under FR2 and FR4 schedules, in which after every second (FR2) or every fourth bar press (FR4) rat received the pellet. The results indicate that the bar pressing for food reward is not altered after induction of experimental diabetes with streptozotocin. It is suggested that insulin lack or hyperglycaemia in this condition fails to influence higher centres associated with regulation of motivated behaviour.