Ontogeny of taste sense.

Developmental changes in the taste receptors and CNS, in physiological and behavioural patterns in fetus and postnatal animals constitute the ontogeny of taste. Tongue epithelial cells are modified into taste buds only with innervation and are seen to degenerate on denervation. On removal of a portion of the tongue, with its taste buds, the central projections of gustation also atrophy, indicating an interdependence of taste receptors and central areas for their development. Gradual transitions in electrical responses to taste stimuli are shown from fetal to adult stage. While responses to ammonium chloride are marked in early fetus, with advancements in age responses to a wide variety of chemicals are shown. Again, early in the development, fibers responsive to chloride are predominant while at a later stage fibers responsive to sodium increase in number. Behaviourally, human fetus and neonatal mammals showed increased swallowing movements on sweet taste and decreased movements on bitter taste which is somewhat at variance with electrophysiological evidence and reflects on the multimodal involvement of taste cell functional and behavioural dynamics with age.

Electroacupuncture, morphine and clonidine: a comparative study of analgesic effects.

This is a comparative study of the analgesic effects of the modified traditional method of analgesia, electroacupuncture (EA), a standard analgesic drug, morphine, a potential analgesic drug, clonidine and the combination of EA + morphine and EA + clonidine. In each case, the index of analgesia (IA) was determined by recording the tail flick latency (TFL) in 60 rats divided into 6 groups of 10 rats each. Group I rats served as control group while Group II-VI were subjected to EA for 20 min (at Zusanli and Kunlun points), morphine (5 mg/kg bw i.p.), clonidine (150 micrograms/kg bw i.p.), EA + morphine and EA + clonidine respectively. TFLs were recorded after the procedure and at 10 min intervals for 150 min or til the TFL returned to¿ the baseline. The IA, analyzed using the Kruskal-Wallis test and its significance determined by multiple comparison test (at 5% level), was found to be significantly different, at various time intervals, in the 6 groups studied.

Airway functions in pregnant Indian women.

The airway functions in pregnancy have been widely studied but reports obtained from Western and Indian population show divergence. While the Indian populations show significant changes in total and timed vital capacity (FVC and FEV1), the Western counterparts dismiss such changes as insignificant. Our results show insignificant alteration in airway function and support the results reported for Western population.

Urinary bladder serosal chemoreceptor induced cardio-respiratory responses: possible pathway.

There is limited experimental information about pain originating from the urinary bladder. In the present study application of 3-5 ml of 1% ammonium oxalate, 1% potassium chloride, 100m M citric acid, IM ammonium chloride, 1% oxalic acid, 0.5% sodium hydroxide, or 2 micrograms/ml bradykinin, to the serosal surface of the urinary bladder in anaesthetized dogs, resulted in an increase in heart rate, rise of both systolic and diastolic blood pressures and increase in respiratory rate and depth. These facilitatory cardio-respiratory responses were coupled with powerful contractions of the urinary bladder wall. By contrast, mucosal application of the chemicals did not bring about any significant change. The cardio-respiratory responses obtained were completely abolished on serosal application of procaine (1%), section of the hypogastric nerves or by spinalectomy at T8. Bilateral cervical vagotomy and pelvic nerve section did not modify the responses. However, the blood pressure responses were abolished by the administration of tolazoline hydrochloride, indicating a major role of sympathetics in this nociceptive reflex.

Morphine-induced modulation of sciatic nerve stimulation evoked blood pressure responses.

Effect of i.v. morphine (1-2 mg/kg) on blood pressure changes evoked by sciatic nerve stimulation (SNS) were studied in chloralose anaesthetised cats. SNS gave a depressor, pressor or a biphasic BP response generally linked to the parameters of stimulation. Morphine produced marked attenuation of depressor and some facilitation of pressor response, suggesting a possible reciprocal relationship between depressor and pressor responses. Depressor response has been correlated with deep tissue or visceral pain mediated through A delta fibres and pressor response to cutaneous nociception involving C fibres or non nociceptive input via group II fibres. Involvement of medullary regions in differential modulation of these depressor and pressor response has been suggested.

Effects of medial septal stimulation & its blockade with atropine on hippocampal rhythmical slow activity in free-moving rabbits.

The influence of the medial septal nucleus (MSN) on hippocampal rhythmical slow activity (RSA) was investigated in hunger motivated free-moving rabbits. Single unit activity of 29 CA3 dorsal hippocampal neurones was studied under two paradigms viz., electrical stimulation (3v/1msec/5Hz) and chemical blockade of atropine-sensitive medial septal cells (dose of 5 micrograms in 5 microliters). The analysis of interspike interval sample histograms recorded with Apple II, along with single unit neuronal spikes recorded on polygraph showed bimodal pattern with two peaks; one at bin 10-20 (high frequency) and second at bin 100-300 (theta frequency). On stimulation of MSN, there was total suppression of bin 100-300 with peaks at bin 1-20 and at bin greater than 1000 (very low frequency). Blockade of cholinergic receptors at MSN showed reduction of bin 100-300 and peak at bin 700- greater than 1000; this was followed by gradual decrease of spike's amplitude and thereafter its total abolition. The results indicate that the septal region is not a pacemaker per se in the genesis of hippocampal RSA (theta rhythm), but serves more in the nature of a relay station for a number of inputs and that its influence on the hippocampal electrical activity depends on the integrity of cholinergic inputs, be it from hippocampus proper or from mid-brain reticular formation.

Significance of CA3 region of hippocampus in memory function.

In mobile unanaesthetised adult rabbits, spontaneous single unit activities of CA3 neurons of Hippocampus showed a specific change in firing pattern in response to conditioned stimuli (CS+). This pattern could be correlated with changes in the general behaviour of these animals. Major deafferntation of the CA3 region did not alter the conditioned response, though neuronal firing pattern and behavioural response changed to that of the pre-conditioned state after antidromic stimulation of CA3 region through fimbria. The importance of CA3 region in memory retention process has been indicated in these experiments.

Visual evoked potential in young adults: a normative study.

It is important to acquire adequate normative data of visual evoked potential before using it as a diagnostic tool. A study using visual evoked potential with pattern (VEP-P) was conducted in Twenty male and seven female young healthy subjects of 17-35 years age. Ag/Agcl electrodes anchored on scalp with collodion at O1-A1, O2-A2 (10-20 system), with transition skin to electrode impedence kept at less than 5 K ohms were connected to MEB 5200 Evoked potential Recorder (Nihon Kohden, Japan). The evoked responses to 256 visual stimuli were recorded using transient pattern reversal (checker size 32'), frequency 1/sec and contrast between black and white checks 67%. The responses were averaged by the computer and absolute peak latency values for P100 alongwith other positive and negative waves worked out. P100 latency of 95.37 +/- 6.85, amp. 6.4 +/- 2.38 for males and 91.07 +/- 49 msec, amp. 6.88 +/- 2.79 microv for females are being reported. The P100 latency values of present study are similar to those reported in age and sex matched subjects of the western world, indicating that there are no ethnic variations in P100 of VEP.

Serum rhodanese in goitre and calcific pancreatitis of tropics.

Rhodanese is one of the enzymes concerned in the detoxification of cyanide. Cassava intake and consequent cyanide toxicity are incriminated in the pathogenesis of goitre and calcific pancreatitis of tropics. So we studied the activity of rhodanese in these patients. 14 controls, 13 patients with pancreatitis and 12 with goitre were studied. The median (and range) of rhodanese in these groups were 82 (50-144), 110 (64-180) and 71 (22-160) units respectively. The serum rhodanese was significantly higher (P less than 0.05) in patients with pancreatitis when compared to the other groups. There was no significant difference between the serum rhodanese in patients with goitre and the controls. The presence of adequate amounts of rhodanese indicates that goitre and chronic pancreatitis are not produced by impaired cyanide detoxification.

Pulmonary diffusion indices in ageing adults.

The lung transfer factor (Tl) was measured by the single breath holding CO technique in 147 apparently healthy males and 88 females of 35-70 years of age, belonging to similar middle class of socio-economic and nutritional status. They were non-smokers, non-alcoholics and had no cardio-respiratory problems at the time of study. The male subjects with average age of 46.9 years, weight 63.9 Kgs, Height 168.9 cms, surface area 1.73 m2, Hb 12.7 gm% had Tl 29.41 +/- 1.78 mlCo/min/mmHg whereas female subjects with average age of 45-60 years, with Wt 63.2 Kgs, Ht. 155.5 cms, Surface area 1.57 m2, Hb 10.88% had Tl 22.49 +/- 1.28 mlCo/min/mmHg. Simple and multiple regression equation for age, Ht, Hb were worked out and their correlation with Tl discussed.

Effect of third ventricular injection of beta-endorphin on the electrophysiological responses of some regions of endocrine hypothalamus.

Multiunit activity (MUA) of arcuate nucleus and cortical EEG were recorded in the regularly cycling female rats on the day of proestrous under urethane anaesthesia. The MUA was compared before and after injection of beta-endorphin in third ventricle. In some animals MUA increased after 30-40 min and persisted for 3-4 hr, in others MUA got inhibited within 5-10 min of injection of beta-Endorphin and effect lasted for 5-6 hr. There was no change in frontoparietal EEG activity. In another group of animals medial pre-optic responses (MPO) to stimulation of medial amygdala were tested before and after ventricular infusion of beta-endorphin. Most of the facilitatory MPO responses got blocked. These observations suggest the involvement of opioid receptors in the mediation of neuroendocrine control of preovulatory events through the amygdalo-preoptico-medial basal hypothalamic axis. There seems to be heterogeneity of beta-endorphin receptors in the arcuate nucleus.

Lung transfer factor (Tl) in a group of healthy subjects.

Lung transfer factor (Tl) was determined by employing single breath technique in fortyfive healthy young males, and twenty females. These subjects belonged to similar socioeconomic and nutritional status and were non smokers. Morning value of Tl in sitting posture was worked out by using Morgan's Pulmotest C while subjects were at physical and mental rest. Male subjects in the age group of (18-26) yrs (av. 21.0 yrs) and height 1.68 M and weight 58.5 kgs, showed Tl of 30.6 +/- 3.8 ml/CO/mm Hg/min and females of same age group, height 1.57 M and weight 49.1 kg, had Tl values of 25.5 +/- 6.2 ml CO/mm Hg/min.