Biomedical subjects
Publications and source records attributed to M G Gogate.
The drive for hoarding food pellets was studied in adult female rats kept on restricted food schedule, by using varying current strength applied through the metal grid. It was observed that the rats maintained higher hoarding score at proestrus and lowest at diestrus at all strengths of currents used in the experiment indicating stronger drive at proestrus.
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Pain threshold was determined in eleven adult male rats (Haffkine strain) on electrical stimulation of midpart of tail. Three responses, namely tail withdrawal, vocalization and vocalization afterdischarge were studied. Of these eleven animals, seven in experimental group were subjected to bilateral electrolytic lesion of mid-dorsal caudate nucleus while remaining four animals were sham operated. The increase in pain threshold after caudatal destruction for all the three responses suggests the possible modulatory role of mid-dorsal caudate nucleus in the mechanism of pain.
Hoarding pattern studied in 28 adult female albino rats indicated cyclic changes in hoarding corresponding to alterations in estrus cycle. It was observed that the hoarding score was maximum at proestrus and the least at diestrus. Animals ovariectomised at proestrus maintained higher hoarding score and those ovariectomised at diestrus stablised on lower hoarding score. Progesterone administration reduced the score in high-score group and Oestrogen administration improved the score in low score group. Alterations in ovarian hormone levels were thus observed to influence hoarding pattern in rats.
The adult female rats hoard large quantities of food during proestrus and continue hoarding if ovariectomised at proestrus (Group I). The hoarding score is lowest in diestrus and continue to remain low if ovariectomised during this phase (Group II). The scores in Group I and Group II are reversed in intracerebral administration of Progesterone and Estradiol Benzoate respectively into preoptic areas. The significance of the response is discussed on the basis of built-in feedback mechanism for hoarding cyclicity.
The present work is designed to study the role of Hippocampus in the control of circadian running activity of rats subject to discrete lesions in ventral hippocampus and having free access to the cues namely food, water, male rat and female rat provided in maze-cum-activity cage indigenously prepared for recording open field behavioral activities. The study was done with 8 male adult albino rats. Those in which lesion was confirmed to be located in antero-ventral hippocampus, exhibited marked increase in running activity with disruption of running activity pattern. There was increase of drive towards socio-sexual cues which were non-rewarding under the present experimental set up. The animals in which lesion was located in posteroventral hippocampal areas showed slight increase in the activity but without disruption of circadian running activity nor was there any significant change in the drive. The functional dissociation observed in present study is believed to be due to involvement of fimbrial/fornical system in the lesion process and therefore responsible for disruption of circadian running activity as well as increase of the running activity in hippocampally-lesioned animals. The present work emphasises the importance of Hippocampus-septum-hippocampus feedback loop in controlling relative time, functioning as internal "stop watch" thus providing a temporal reference and detecting phase relation during activity. Interruption of this loop in hippocampally-lesioned rat probably leads to failure to inhibit inappropriate responses and failure to discriminate rewarding and non-rewarding cues.
Maze-cum-activity cage is devised in order to record the activity shift patterns of incentive drive of rats. The main features of this instrument are its low cost, simplicity or recording system and evaluation of time shift patterns of the activity when animal is moving for preferential cues such as food, water socio-sexual environment provided in the cage during a 24 hour period.
The present study revealed that the rats kept on two hour meal schedule hoarded large quantity of food as compared to their hoarding score when kept on food ad lib. Body weights were maintained even though the food intake was slightly reduced. Hunger seems to a stronger drive for hoarding.