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Biomedical subjects

J F Pujol

Publications and source records attributed to J F Pujol.

At least 145 records · Page 8Linked to original sources
PubMed1977

Daily variations of various parameters of serotonin metabolism in the rat brain. I. Circadian variations of tryptophan-5-hydroxylase in the raphe nuclei and the striatum.

Daily changes in tryptophan-5-hydroxylase (TrH) activity have been studied in six different 5-HT-containing cell groups (B3, B4, B5, B6, B7, B8,) in the brain stem of rats maintained in a regular cycle of 12 h of light and 12 h of darkness. Significant circadian alternations of TrH activity were observed in most of the raphe nuclei tested, although the changes were not identical from one structure to another. The striatum showed daily variations in TrH activity in opposite phase to the nucleus raphe dorsalis which projects specific terminals into this area. Monoamine oxidase (MAO) activity was simultaneously estimated in these nuclei but did not exhibit and significant rhythm, suggesting a specific regulation of TrH. Total protein levels were also subject to daily changes.

Animals↗
PubMed1977

Daily variations of various parameters of serotonin metabolism in the rat brain. II. Circadian variations in serum and cerebral tryptophan levels: lack of correlation with 5-HT turnover.

Rats submitted to regular 12 h cycles of light and darkness for three weeks were sacrificed at various times of the day. 5-HT, 5-HIAA and tryptophan levels were estimated in the fronto-parietal cerebral cortex. Tyrosine and free and total tryptophan levels in serum were estimated in parallel. Significant circadian variations in 5-HT and 5-HIAA levels were found in cerebral tissues. The peaks of 5-HIAA levels were dectected during the lignt and dark periods respectively, the maximal fluctuations being seen between 17.00 h and 21.00 h, two times separating the light off. Important significant circadian variations in free and total serum tryptophan levels were also observed. In both cases, the maximal levels were found during the middle of the dark phase after the peak of 5-HIAA levels. The circadian rhythm of tyrosine levels in serum was in opposite phase with that of tryptophan (free or total). The diurnal changes in tryptophan content in cerebral tissues seemed thus related to those found in serum. Taking in consideration results obtained in previous studies 16,17 carried out in similar experimental conditions, it was concluded that the parallel increase in serum free tryptophan and in tissues 5-HIAA levels seen during the night were not related to a stimulation of 5-HT turnover. Indeed 5-HT synthesis is minimal at this time16.

Amino Acids↗
PubMed1976

Time-course variations in tyrosine hydroxylase activity in the rat locus coeruleus after electrolytic destruction of the nuclei raphe dorsalis or raphe centralis.

Time-course variations in tyrosine hydroxylase activity were measured in the locus coeruleus of the albino rat after electrolytic coagulation of either the nucleus raphe dorsalis or the nucleus raphe centralis. Highly significant increases were measured at 4 days after lesioning of the raphe dorsalis (30.33%) and the raphe centralis (81.55%) compared with control values, whereas the activity in groups A9 and A10 was unchanged at this time-point. In conjunction with other experimental evidences, an hypothesis is proposed that the catecholaminergic neurons located in the locus coeruleus are directly and/or indirectly controlled by the serotonin-containing neurons located in the anterior raphe system nuclei.

Animals↗
PubMed1976

[Effects of lesions in the pontine tegmentum on the sleep stages in the rat].

1. Limited coagulations of the locus coeruleus and subcoeruleus nuclei have been performed in rats and the sleep-waking cycle was continuously monitored during 9 days. The cortical and diencephalic noradrenaline content was mesured at the termination of the experiment, on the 10th post lesion day. 2. The bilateral destruction of the locus coeruleus is followed by the appearance of a uro-genital syndrome consisting of hema turia, bladder distension and penile erection. The states of sleep are disturbed during the first two days (increase of slow-wave sleep and decrease of paradoxical sleep times) and thereafter return to normal. Additionally, an hyperthermia appears during the third experimental day. The cortical and diencephalic noradrenaline content decrease to 70%. 3. The simultaneous lesion of both locus coeruleus and subcoeruleus nuclei is followed by the appearance of an aphagia adipsia syndrome in addition to the uro-genital syndrome. After these lesions, it is no long possible to find paradoxical sleep episodes in polygraphic recordings while the amount of slow wave sleep is normal. Cortical and diencephalic noradrenaline content decrease more than 50%. 4. In normal rats direct injection of 6 hydroxydopamine directly in both locus coeruleus and nuclei subcoeruleus had no discernable effects either on the behaviour or on the states of sleep. The cortical noradrenaline content decreased 30% below control values. 5. These results are consistent with but do not prove the hypothesis that part of the pontine tegmentum might play an important role in triggering paradoxical sleep episodes. The role of these regions in the regulation of internal temperature, food consumption and bladder motricity is also discussed.

Animals↗
PubMed1975

[Hypersomnia by isthmic lesion in cat. Study of the metabolism of cerebral monamines].

(1) A significant increase of 5-HT synthesis is observed in several areas of the cat brain 24 h after the bilateral destruction of the dorsal noradrenergic bundle in the isthmus. This stimulation of the synthesis was simultaneously observed at the level fo serotoninergic cell bodies (anterior part of the raphe system) and of 5-HT terminals (cortex, thalamus, mesencephalon, medulla oblongata). Conversely, a significant decrease of 5-HT synthesis was found in the caudal part of the raphe and in the hypothalamus. The possibility of a catecholaminergic control of 5-HT synthesis by neurons passing through the isthmus is discussed. (2) in the same experimental conditions, an important decrease of endogenous dopamine content without any subsequent change of noradrenaline concentration was observed in the thalamus, the geniculate body and the pons. This important decrease could be due to a greater utilization of dopamine into hypothetical dopaminergic terminals localized in these structures.

Animals↗