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Biomedical subjects

P Parkash

Publications and source records attributed to P Parkash.

9 recordsLinked to original sources

State of pregnancy modifies lead toxicity in mice.

Toxicity of lead acetate after administration through the oral route at 0-50 mg/kg body weight of animal has been assessed in the liver of pregnant mice and compared with the effect in the liver of nonpregnant dams. Analysis showed that the basal level of hepatic lead is considerably reduced during pregnancy as compared to that in nonpregnant state. After administration of Pb-acetate, deposited lead in liver of nonpregnant mice was 3- to 4-fold while in pregnant mice was, it was 1.8- to 3.0-fold over their respective control values. Although hepatic Fe, Cu, and Zn levels had a tendency to be lowered during pregnancy, it appeared that the added trace quantity of lead prior to and during pregnancy helped in the retention of these metals, which either remained unaffected (as Fe) or declined (Cu and Zn) after lead administration during the nonpregnant state. The effect of lead on Mn diminution, however, was visible at the dose of 50 mg/kg body wt of lead-acetate. Alkaline phosphatase, which increased during pregnancy along with Mn, was reversed between the pregnant and nonpregnant states after oral administration of lead. On the other hand, the level of delta-aminolevolunic acid dehydratase, which declined during normal pregnancy, continued to fall further after lead exposure. It is concluded that the distribution of basal or administered lead and its effect on enzyme activities and trace metal composition in liver depends on the pregnant and nonpregnant states of female hosts.

Administration, Oral↗

Renal toxicity after oral administration of lead acetate during pre- and post-implantation periods: effects on trace metal composition, metallo-enzymes and glutathione.

The present study was undertaken to compare the effects of 10-50 mg/kg b.wt. of Pb acetate after chronic treatment through oral gavage on: (a) the distribution of trace elements such as Fe, Cu, Zn, and Mn, (b) enzyme activity of delta-amino levulinic acid dehydratase (delta-ALAD) and alkaline phosphatase, and (c) glutathione (GSH) in kidney and (d) delta-ALAD in blood of pregnant and non-pregnant mice. Treatment with Pb acetate was given on every alternate day for 4 weeks prior to mating and for 3-4 weeks until pregnancy became apparent and confirmed by laporatomy. Lead administration reduced the rate of reproduction as assessed by number of living viable embryos. During normal pregnancy renal Cu, Fe and GSH tended to decline although non-significantly and continued to do so after lead administration. Mn was considerably and significantly elevated, whereas activity of delta-ALAD (non-activated) was quite low in pregnant mice. Following administration of Pb acetate, kidneys of pregnant and non-pregnant dams accumulated Pb in a dose-dependent manner, but as compared to non-pregnant mice, Pb increase in pregnant dams was significantly lower. Pb toxicity was associated with the loss of delta-ALAD in blood and kidney, but unlike the non-activated form of delta-ALAD, the dithiothreitol-activated form of delta-ALAD declined in a significant amount. The residual activity showed a high degree of negative correlation with endogenous Pb as well as with Zn/Pb ratio. Pb toxicity did not modify renal Fe, Cu, and Zn in the pregnant state, but reduced renal Fe during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

Response of canine brain loci to intracerebroventricular thyroxine.

The effect of intracerebroventricular T4 on certain hypothalamic i.e., POA and VMN and cortical i.e., HPC and CO loci was investigated by recording their electroencepgraphic activity after chronic implantation of cannulae and bipolar electrodes in ten male dogs. Recordings were made for two hours after the microinjection. The predominant pattern of EEG activity was a synchrony of brain waves in all derivations except for POA where biphasic desynchronization-synchronization was observed. Final synchrony suggest refractoriness of these loci to T4 which might be playing a protective role.

Animals↗

Electroencephalographic response of canine hippocampus to intraventricular GABA.

The effect of intraventricularly administered GABA on hippocampus was investigated by recording its electrical activity after chronic implantation of cannulae and bipolar electrode in five male beagle dogs. GABA was introduced in 40 mg/Kg b. weight so as to exceed its physiological levels in CSF. Recordings were made within two hours after microinjection in third ventricle. The predominant pattern of EEG depicted synchronization. The progressing synchronization of EEG suggests induction of functional lesion which might be playing a protective role in the regulation of metabolic behaviour.

Animals↗

Responses of pre-optic area to intracerebroventricular thyroxine and thyrotropin in dog brain.

Electroencephalographic activity (EEG) of pre-optic area (POA) was recorded after intracerebroventricular (ICV) microinjection of thyroxine (T4) and thyrotropin (TSH) in conscious male dogs. Recordings were made for two hours following microinjections. Biphasic responses with increased amplitude were observed in both the treatments, but chronologically the responses obtained with T4 & TSH were opposite to each other.

Animals↗

Possible action of intracerebroventricular thyrotropin on Brobeck's hypothesis.

The effect of ICV administered TSH on Brobeck's thermostatic hypothesis was evaluated by recording chronological changes in electrical activity of precise loci (POA, VMN and CO) coupled by rectal temperature changes in dogs. The study revealed 1. TSH action on thermoregulation is biphasic in nature. 2. This action of TSH is not an independent act but depends on the reaction of satiety centre.

Animals↗

Ethanol induced electroencephalographic changes from certain central loci of canine brain.

Effect of intracerebroventricular (i.c.v.) ethanol on pre-optic area (POA) and hippocampus (HPC) was investigated by recording chronological changes in their electroencephalographic (EEG) activity, through chronically implanted cannulae and bipolar electrodes, in five conscious male beagle dogs. Recordings were made for two hours after microinjection and compared with cortical (CO) tracings. The predominant pattern of EEG activity from subcortical loci was high voltage discharges though synchronization was also observed. Cortical EEG depicted slow waves with some potentiation. The study demonstrated similar type of response form POA and HPC, which was different from CO, suggesting that ethanol produces different actions at subcortical and cortical level.

Adult↗