Browsing by Author "P.K. Dey"

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Accumulation of serotonin in human cerebral contusion
(1978) S. Mohanty; P.K. Dey; P.C. Sen; A. Ray
Brain tissue from ten patients with gross evidence of brain contusion and edema following trauma was examined for serotonin content by histofluorescent examination. There was evidence of an accumulation of serotonin and its diffusion towards the surrounding tissues in contusions.
Age-related pathophysiology of the blood-brain barrier in heat stress
(1992) H.S. Sharma; R. Kretzschmar; J. Cervós-Navarro; A. Ermisch; H.-J. Rühle; P.K. Dey
The possibility that the blood-brain barrier (BBB) might play an important role in the pathophysiology of heat stress (HS) has been examined in young (age 8–9 weeks) and adult (age 24–32 weeks) rats. Exposure of young rats to 4 h HS at 38°C in a biological oxygen demand (BOD) incubator (relative humidity 47–50%, wind velocity 20–26 cm/sec, simulating the environmental conditions of Varanasi, India, during the month of June) resulted in a marked hyperthermia (41.7 ± 0.23°C) and behavioral symptoms. In these animals there was a profound increase in the permeability of the BBB to Evans blue-albumin (EBA) (464%) and to 131I-sodium iodide (515%), accompanied by a marked increase in the brain water content (4%), of the levels of serotonin (5-hydroxytryptamine, 5-HT) in plasma (687%) and in brain (267%) and a pronounced reduction (30%) in cerebral blood flow (CBF). Morphological examination using light- and electron-microscopy revealed profound neuronal changes associated with a marked increase in glial fibrillary acidic protein (GFAP) and in vimentin immunoreactivities, together with a substantial reduction in myelin basic protein (MBP) immunostaining in the brain. These changes were more pronounced in the brain-stem reticular formation, pons and medulla region. On the other hand, exposure of adult animals to the same intensity of HS resulted in mild or no changes in BBB permeability, content of brain water and 5-HT in the plasma and brain, CBF or other cellular changes. The results show that the young animals are more vulnerable to BBB damage in HS, and this can be instrumental in precipitating cellular and pathophysiological changes in the brain. The probable mechanism(s) are discussed. © 1992, Elsevier Science Publishers, B.V.
Anterior cerebellum as a site for morphine analgesia and post-stimulation analgesia
(1982) P.K. Dey; A.K. Ray
[No abstract available]
Blood lead levels in children with neurological disorders
(Oxford University Press, 1998) Ashok Kumar; P.K. Dey; P.M. Singla; R.S. Ambasht; S.K. Upadhyay
Blood lead levels were measured by atomic absorption spectrometry in 82 children suffering from various neurological disorders (cerebral palsy 42, seizure disorders 35, acute encephalopathy of unknown origin 5) and in 28 healthy children, aged 1 to 12 years. Mean blood lead levels were 11.96 ± 10.97 μg/dl in control children and 19.30 ± 17.65 μg/dl in children with neurological disorders. A significant number of control children as well as those who had neurological disorders were found to have blood lead concentrations of ≥ 10 μg/dl and ≥ 20 μg/dl, the cut-off limits for lead poisoning and medical evaluation, respectively. Blood lead levels were, statistically, elevated in children with cerebral palsy compared to controls. Children with pica behaviour exhibited higher blood lead concentrations.
Cerebral oedema and blood-brain and blood-CSF barriers in experimental brain trauma: Effect of indomethacin - a prostaglandin synthetase inhibitor
(1980) S. Mohanty; A.K. Ray; P.K. Dey
[No abstract available]
Effect of indomethacin (a prostaglandin synthetase inhibitor) on the permeability of blood-brain and blood-CSF barriers in rat
(1980) P.K. Dey; H.S. Sharma; K.S. Rao
[No abstract available]
Effect of prostaglandin synthetase inhibitor on permeability of blood brain and blood-CSF barrier
(1978) P.K. Dey; H.S. Sharma
[No abstract available]
Effect of prostaglandin synthetase inhibitor on the permeability on blood-brain and blood-CSF barrier
(1978) P.K. Dey; H.S. Sharma
[No abstract available]
Effect of voluntary retention of urine on plasma and urinary biogenic amines as well as circulatory and respiratory responses
(1982) M. Shukla; S.N. Tripathi; P.K. Dey
[No abstract available]
Electrophysiological studies in children with paralytic poliomyelitis
(1995) U. Prakash; A.K. Sinha; B. Mukherjee; G.P. Katiyar; P.K. Dey
H-reflex latency (H-RL) and H/M ratio were measured in normal children and children with paralytic poliomyelitis of 1-3 years of age. The H-RL was considerably increased in both the involved and uninvolved limbs of the patients, whereas the H/M ratio did not differ. The Mmax value in the involved limb was very low and therefore, a corrected H/M ratio was calculated for that side only. The corrected H/M ratio was significantly less than the H/M ratio observed in the uninvolved and control limbs. The distal motor latency was also increased in the involved side.
Exercise training: Significance of regional alterations in serotonin metabolism of rat brain in relation to antidepressant effect of exercise
(1992) Sangita Dey; R.H. Singh; P.K. Dey
Alterations of 5HT and its chief metabolite 5HIAA were studied in four regions of the rat brain following acute 1-h swim exercise and 4 week chronic swim exercise (30 min/day, 6 days per week). Acute exercise significantly increased the synthesis and metabolism of 5HT in brain stem. Hypothalamus also showed increased levels of 5HT. However, no changes were observed in the cerebral cortex and hippocampus. Chronic exercise activated not only the synthesis but also the metabolism of 5HT in the cerebral cortex; this neuronal adaptation was sustained even 1 week after the termination of training. In brain stem, increased 5HT turnover was observed immediately after training. In hypothalamus, decrease in 5HT and 5HIAA levels occurred immediately after training, followed by a rebound increase in their levels after 1 week posttraining rest. In hippocampus, a delayed effect was observed, because 5HT level was unaltered immediately after the training, but its turnover decreased after 1 week rest. These findings have been discussed in an attempt to explain the antidepressant effect of exercise based on the 5HT deficiency theory of endogenous depression. © 1992.
Histamine modulates heat stress-induced changes in blood-brain barrier permeability, cerebral blood flow, brain oedema and serotonin levels: An experimental study in conscious young rats
(1992) H.S. Sharma; F. Nyberg; J. Cervos-Navarro; P.K. Dey
The possibility that endogenous histamine plays an important role in modulating the pathophysiology of heat stress was examined in young rats using a pharmacological approach. Subjection of young animals (six to seven weeks old) to heat stress at 38°C for 4 h in a biological oxygen demand incubator (relative humidity 47-50%, wind velocity 20-25 cm/s) resulted in a profound increase in blood-brain barrier permeability to Evans Blue albumin (whole brain 375%) and [130I]sodium (whole brain 478%)) along with a significant reduction in the cerebral blood flow (mean 34%). The water content of the whole brain was elevated by 4.5% (about 19% volume swelling) from the control. At this time-period, the plasma and whole brain 5-hydroxytryptamine levels were elevated by 656% and 328%, respectively, from the control group. Pretreatment with cimetidine (a histamine H2 receptor antagonist) significantly thwarted the increases in the brain water content and the blood-brain barrier permeability. In cimetidine-pretreated animals, the cerebral blood flow was significantly elevated and the plasma and brain 5-hydroxytryptamine (serotonin) levels were slightly but significantly reduced as compared with the untreated stressed group. However, prior treatment with mepyramine (a histamine H1 receptor antagonist) neither attenuated the changes in water content and the blood-brain barrier permeability nor altered the cerebral blood flow and 5-hydroxytryptamine levels. In fact, there was a significantly higher permeation of the tracers across the cerebral vessels in these drug-treated animals along with a greater accumulation of the brain water content as compared with the untreated stressed group. The cerebral blood flow and 5-hydroxytryptamine levels showed only minor changes from the untreated stressed group. These results show, probably for the first time, that (i) the endogenous histamine plays an important role in the pathophysiology of heat stress and (ii) this effect appears to be mediated via specific histamine H2 receptors. © 1992.
Impairment of blood-brain barrier (BBB) in rat by immobilization stress: Role of serotonin (5-HT)
(1981) H.S. Sharma; P.K. Dey
[No abstract available]
Increased 5-hydroxytryptamine immunoreactivity in traumatized spinal cord - An experimental study in the rat
(Springer-Verlag, 1990) H.S. Sharma; J. Westman; Y. Olsson; O. Johansson; P.K. Dey
The possibility that serotonin (5-hydroxytryptamine, 5-HT) is involved in the early tissue reactions occurring in spinal cord trauma was examined in a rat model using an immunocytochemical technique. The injury was made in the form of a 5-mm long and 2.5-mm wide lesion of the right dorsal horn at the level of T10-11. Injured rats, pretreated with the 5-HT synthesis blocking agent, p-chlorophenyl alanine (p-CPA) were compared with untreated injured controls and the animals were allowed to survive for 5 h. The distribution of 5-HT was examined in proximal and distal cross-sections of the cord, located 2 and 5 mm away from the injury. Normal rats showed immunoreactive material in nerve cell processes and in a few nerve cell bodies of the ventral horns. The trauma to the spinal cord caused a marked increase in 5-HT immunoreactivity in the segments located 2 mm proximal and distal to the injury, particularly in the ipsilateral ventral horn. The segment located 5 mm distal to the lesion showed a similar increase in immunoreactivity but it was apparently less pronounced in the corresponding proximal segment. Treatment with p-CPA markedly reduced the trauma-induced increase in 5-HT immunoreactivity in all the segments. These immunohistochemical findings were in line with the changes in the contents of 5-HT measured biochemically in corresponding spinal cord segments. At the onset of the trauma to the spinal cord 5-HT is thus present in the tissue, mainly in the form of 5-HT-containing nerve cell processes. Biochemical determinations also revealed that there is an increased amount of 5-HT in the traumatized spinal cord. The present study indicates that this is at least partly due to an increased amount of 5-HT in neurons and nerve cell processes of the perifocal region. The pathophysiollogical significance of the observed 5-HT-reaction in spinal cord injury is not known in all its details. However, 5-HT might be implicated in such tissue reaction, such as increased microvascular permea bility and edema formation occurring in the early period after trauma. © 1990 Springer-Verlag.
Increased blood-brain barrier (BBB) permeability in stress: Blockade by parachlorophenylalanine (pCPA) pretreatment
(1980) H.S. Sharma; P.K. Dey
[No abstract available]
Influence of ambient temperature and drug treatments on brain oedema induced by impact injury on skull in rats
(1984) P.K. Dey; H.S. Sharma
[No abstract available]
Influence of glycyl-proline (a dipeptide sequence of β-LPH at 43-44 position) on central actions of morphine
(1982) A.K. Ray; P.K. Dey
An endogenous dipeptide, located in 43-44 position of β - LPH chain, markedly antagonises morphine analgesia in rats but has no effect on morphine catatonia. A dose of 50 ug/100 g body weight of it shows about 80% antagonism. The site of its antagonistic action appears to be on the ventral surface of the brain stem. This dipeptide has further been shown to markedly facilitate the development of tolerance to morphine analgesia. Structure-activity relationship of this dipeptide demonstrates that the cationic amino group of glycine and hydrophobic moiety of proline are essential for exhibiting antagonism against morphine analgesia. © 1982.
Involvement of endogenous opiates in heat stress
(2000) P.K. Dey
The present study is directed to examine the role of endogenous opiate system towards thermoregulatory response of rats exposed to either acute or chronic heat stress for 21 days. The results show that following blockade of opiate mu receptor by administration of naioxone (i.p.), the thermoregulatory adaptive mechanisms activated by exposure of rats to hot environment for an acute or chronic exposure were seriously impaired, specially death occurred often in chronic heat exposure group associated with rise of rectal temp. to 41° C. However endogenous opiates are not tonically active in normal regulation of body temperature as evident from the naloxone's inability to produce a change in body temperature at normal amblent temperature.
Involvement of histamine receptors in mediation of histamine induced thermoregulatory response in rats
(1986) P.K. Dey; N. Mukhopadhaya
[No abstract available]
Modification of functional responsiveness of central serotonin receptor subtypes in rats following exposure to chronic heat stress
(1999) P.K. Dey
Evidences are galore to suggest a close involvement of serotonergic neurons for thermoregulatory adjustment in a hot environment. The present study further supports this view. Studies of behavioral responses elicited by activation of postsynaptic 5HT receptor (serotonin syndrome), somatodendritic autoreceptor (Hyperphagic response) and postsynaptic 5HT2 receptor (wet-dog shake response) following administration of 5HT receptor agonists (8-OH-DPAT, 5-MeODMT and quipazine) in rats exposed to 3 week chronic heat stress clearly demonstrate that there occurred enhanced responsivity of 5HT2 receptor simultaneously with reduced sensitivity of presynaptic autoreceptors and postsynaptic 5HT receptors in warm acclimated rats. Further, such adaptive responses of 5HT receptor subtypes are suggested to take place in serotonergic system anatomically located in brain-stem region which constitute an extrahypothalamic centers for thermoregulatory activity.