Role of striatal dopamine in the lordosis behaviour.

Effects of intrastriatal injections of haloperidol (Dopamine antagonist) and D-amphetamine (Dopamine agonist) on lordosis behaviour were studied in ovariectomized female albino rats, after priming with subcutaneous injections of estrogen and progesterone. The lordosis quotient (LQ) significantly increased after haloperidol, and decreased following D-amphetamine treatment. However, the inhibitory effect of D-amphetamine was transient and could be reversed by haloperidol in the same animal when given one hour after the D-amphetamine injection. The ovarian hormones probably act centrally to suppress the DA system in the striatum thereby enhancing the tonic and dorsal immobility responses associated with lordosis.

Effect of intensity and duration of stress on male sexual behaviour.

Male rats were exposed to four different stress conditions, varying in duration and intensity, during separate periods and their copulatory behaviour was studied. The number of mounts and time spent in other sexual behaviours were reduced with intensity of stressor being primarily responsible rather than prolongation of duration of a less severe stress condition.

Effect of stress on organ weight in rats.

The effect of 90 minute supine restraint or forced swim stress, on weights of various organs in sixty adult male albino rats was studied. One group of twenty rats served as control; second group of twenty was immobilized and third group of twenty was forced to swim in water at room temperature. The animals were studied for a period of 15 days. During this period, they were subjected to 90 minutes of stress everyday at the same time. Both the groups of stressed animals showed a statistically significant increase in weight of cerebrum, cerebellum, pituitary, thyroid, and adrenals. Testes and seminal vesicles showed no significant change in weight. There was an apparent increase in weight of liver after immobilization stress, and a statistically significant increase in its weight in forced swim group. Therefore, immobilization and forced swim stresses produce an increase in the weight of brain cerebrum and cerebellum, endocrine organs and liver.

Role of caudate nucleus on modulation of blood pressure responses in cat.

Changes in blood pressure, heart rate and respiration were studied in 15 cats on bilateral stimulation of rostral, middle and caudal regions of caudate nucleus. Hypotensive response was obtained on stimulation of anterior caudate nucleus, which changed to pressor response when posterior caudate nucleus was stimulated. Biphasic blood pressure responses were recorded on stimulation of middle caudatal area. No detectable changes were observed on heart rate and respiration. This suggests a role for caudate nucleus as a modulator in blood pressure regulation.

Effect of interaction between glucose or sodium chloride ingestion and ovarian hormones on some endocrine organs in rats.

Adult female rats with normal oestrus cycles (control), ovariectomized (OVX), ovariectomized with estradiol treatment (OVX-EB) and ovariectomized with progesterone treatment (OVX-P), were provided with Glucose (G/W) or Saline (S/W) through a two bottle preference. They were given food pellets ad libitum. At the end of 3 weeks' period the animals were sacrificed and pituitary, thyroid, adrenal and pancreas were removed and weighed. Adrenal glands showed a significant decrease in OVX and OVX-P rats taking G/W, as also decrease in OVX and OVX-EB and increase in OVX-P rats taking S/W. The pancreas registered an overall increase in OVX, OVX-EB and OVX-P rats taking both G/W and S/W, which was statistically significant only in OVX-EB and OVX-P rats. Ovarian hormones appear to influence the size of these glands when glucose or sodium chloride is ingested.

Differential role of ovarian hormones for taste preferences in rats.

The effects of estrogen (OVX-EB) and progesterone (OVX-P) administration to ovariectomized (OVX) rats on food and fluid intakes were studied in fifty five animals grouped into three series. Animals in each series were given a choice of two fluids viz. tap water and either 5% glucose (5 G/W) or 12% glucose (12 G/W) or 1.5% Sodium chloride (S/W) by two bottle preference. Both hormones had a differential effect on the ingestion of the two concentrations of glucose while progesterone markedly increased the intake of Sodium Chloride. Could the putative role of the ovarian hormones be hedonic for glucose and homeostatic for salt?

Effects of adrenalectomy on brain weight, body weight and weight of certain endocrine organs in rats.

Albino rats, both males and females were adrenalectomized (Adx.), either on the eleventh or the twenty fifth day after birth and the body weights recorded daily until the sixtieth day when all the animals were sacrificed. Brain (cerebrum and cerebellum), pituitary, thyroid and gonads were weighed post mortem. Body weights decreased in all the Adx. animals, the decrease being statistically significant in the male rats Adx. on day 11 (p less than 0.05). Both cerebrum and cerebellum recorded a significant increase in weight in both the male Adx. groups, whereas pituitary, thyroid and gonads showed a significant decrease. Changes observed in 25 day Adx. female rats were not statistically significant. Thus, adrenalectomy in the young rats appears to have differential effects on the somatic, neural and endocrine growth.

Effect of mid-dorsal caudate nucleus on conditioning for pain stimulus in rats.

Male rats were subjected to conditioning, with light source as conditioned stimulus, followed by a noxious stimulus applied to the tail as unconditioned stimulus. There was development of conditioned response after a few days, which was inhibited later on.

Role of acetylcholine and dopamine in dorsal hippocampus on hoarding behavior in rats.

The probable roles of Acetylcholine (Ach) and Dopamine (DA) in the modulation of instinctual behaviors of feeding and hoarding (HS), as also the body weight and vaginal cyclicity (EI), were studied by instillation of Atropine (Ach antagonist), Haloperidol (DA antagonist) and Apomorphine (DA agonist) in the dorsal hippocampus of nonpregnant female rats. It was observed that the HS was significantly decreased with both Atropine and haloperidol and increased with Apomorphine, although the food intake was decreased with the three chemicals. It appears that action of both Ach and DA on the dorsal hippocampus has a positive influence on hoarding behavior.

Variations in hoarding behavior following regional hippocampal lesions in rats.

Instinctual behaviors of feeding (food intake) and hoarding (HS) so also the body weight and estrus cycles (EI) were studied before and after discrete bilateral electrolytic lesions of dorsal hippocampus in female rats. Following the lesions, there was significant increase in food intake, body weight, hoarding score and disruption of 4-5 days estrus cycles with EI of more than one, as compared to the control (prelesioned) period and the sham operated rats. Lesions of ventral hippocampus in the earlier study (Indian J exp Biol, 26 (1988) 53) had shown a significant decrease in hoarding thus suggesting a differential role of the hippocampus probably mediated through the amygdala and/or hypothalamus both of which either alone or together exert a more direct and pivotal control in the feeding and hoarding behaviour.

Ingestive behaviour of starved rats after single intraperitoneal injection of fresh plasma from well-fed rats.

Ingestive behaviour of control and experimental rats following 96 hours of starvation was studied. The control animals were injected normal saline intraperitoneally (I.P.) whereas the experimental animals were injected I.P. with fresh plasma obtained from well fed rats. Having been presented with food 15 minutes after the injections, the food intake (Gms +/- SEM) of control animals for the first five hours after injection was 6.00 +/- 0.44, whereas, the intake in experimental animals for the same period was 0.55 +/- 0.05. The food intake was significantly suppressed for the next three days, attaining the normal values by the 4th day. Since all the rats were starved prior to injection, all of them increased in weight during the four days of study, but the increase seen in the experimental group was much subdued. Therefore the plasma factor, suppresses not only the food intake but also the gain in body weight.

Effect of dorsal hippocampal lesion compared to dorsal hippocampal blockade by atropine on reference memory in vision deprived rats.

In order to study the primacy of the hippocampus in place learning function 24 male adult albino rats were hippocampally-lesioned in dorsal hippocampus involving fornical damage (group I); sham operated for comparison with group I (group II); cannulated for instillation of atropine sulphate in the same loci as group I (group III); and cannulated for instillation of saline which served as control for group III (group IV). All the animals were enucleated and their reference memory (long-term memory) was tested, using open 4-arm radial maze. There was loss of reference memory in groups I and III. However, hippocampally-lesioned animals, showed recovery of reference memory deficit within a short period of 10 days or so. Whereas atropinized animals showed persistent reference memory deficit as long as the instillation effect continued. The mechanism involved in the recovery of reference memory in hippocampally-lesioned animals and persistent deficit of reference memory in atropinized animals has been postulated to explain the primacy of hippocampus in the place learning function under normal conditions.

Effect of immobilization stress on food intake, body weight and weights of various organs in rat.

Effect of immobilization stress was studied in male albino rats. Experimental rats (E) were restrained in close-fitting wiremesh cylinders. Control rats (C) were not subjected to restraint. Food and water were made available to C for all the 24 hrs while the E were given them for only 6 hrs daily. The initial lower food intake of E was later reversed to near normal levels. There was a steady fall in the body weights of E, while the C displayed a normal growth rate. Cerebrum, cerebellum, pituitary and adrenals of E weighted significantly more. There was an apparent increase in the weight of thyroid. Gonads displayed no change in weight. The results indicate that chronic restraint causes loss of body weight inspite of a near normal food intake. It also produces an increase in the weight of brain, and certain endocrine organs.

Effect of stress on maternal behaviour.

Primiparous female rats subjected to foot shock and/or immobilization stress were tested for maternal behaviour (MB) by determining the pup retrieval rate (PRR) for 5 minutes. On the third day after parturition PRR significantly decreased when foot shock was given and the fall was more pronounced after immobilization both with and without foot shock. The animals exhibited enhanced MB on the 12th day as compared to the third day, but the stressful situations produced significant decreases in MB qualitatively similar to the third day. By the 20th day when the weaning was in progress the MB decreased to the 3rd day levels. This change in the MB may be due to the changes in the pattern of prolactin secretion during the post partum period.

Four-arm radial open maze (FAROM) as a tool for assessing the effect of atropine in spatial memory of the rats.

Place learning behaviour for working (short term) memory and reference (long term) memory is studied with the Four-arm radial open maze (FAROM) in 18 rats divided equally in three groups. In group I, 0.5 mg of atropine was injected intra-peritoneally 30 minutes before the trial. In group II, saline and in group III Glycopyrrolate were injected instead. Twenty three hours hungry animals were tested on each day in the maze to search for food kept in one of the eight cul-de-sacs of maze. The latency i.e. the time to reach the goal cul-de-sacs, as well as the error score i.e. the number of entries in the non-goal cul-de-sacs were counted during six consecutive trials, per day. Each trial duration was 5 minutes or the time taken by the animal to search the goal compartment whichever was less. The inter-trials period was 10 min and the work was carried out for a period of 3 weeks. The results show that atropine does block effectively both the memory faculties i.e. working and reference memory and that level of memory deficit induced by atropine is related to the rate of drug uptake by the central cholinergic receptors.

Autonomic responses to breath holding and its variations following pranayama.

Autonomic responses to breath holding were studied in twenty healthy young men. Breath was held at different phases of respiration and parameters recorded were Breath holding time, heart rate systolic and diastolic blood pressure and galvanic skin resistance (GSR). After taking initial recordings all the subjects practised Nadi-Shodhana Pranayama for a period of 4 weeks. At the end of 4 weeks same parameters were again recorded and the results compared. Baseline heart rate and blood pressure (systolic and diastolic) showed a rendency to decrease and both these autonomic parameters were significantly decreased at breaking point after pranayamic breathing. Although the GSR was recorded in all subjects the observations made were not conclusive. Thus pranayama breathing exercises appear to alter autonomic responses to breath holding probably by increasing vagal tone and decreasing sympathetic discharges.

Role of medial preoptic area (MPOA) in the reproductive function and feeding behavior in rats.

Adult female rats were given ad lib access to two pairs of specially prepared diets containing the three macro-nutrients, protein, fat and carbohydrate, in such proportion that both pairs were isocaloric but one pair varied in protein content (45% and 5%) and the other pair in carbohydrate content (70% and 25%). Body weights, food intake and selectivity were noted daily. Following lesions of Medial Preoptic Area (MPOA), there was an increase in the total food and protein intake and disruption of the regular estrus cycles. In the second series, the total food intake increased after ovariectomy and decreased following intracranial estrogen instillation in the MPOA. A change in the selectivity of the diets was also noted. The observations are suggestive of the role of MPOA in the food intake and selectivity and this is probably effected through the estrogen receptors situated therein.