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J M Pequignot

Publications and source records attributed to J M Pequignot.

116 records · Page 7Linked to original sources
PubMed1978

[Effect of submaximal muscular exercise of short duration on urinary excretion of catecholamines, DOPA and their metabolites].

Thirteen human subjects were submitted to a moderate muscular work on ergometric bicycle (at intensity corresponding to 80% of maximal oxygen uptake during 10 min). No modifications were observed in the urinary amounts of the three catecholamines (A, NA, DA), DOPA, DOPAC and 3-MT. On the contrary, the excretion of metadrenaline (MN) and normetadrenaline (NMN) was slightly increased, showing a mild stimulation of adrenergic system. Our result point out the interest of urinary methoxyamines as useful index of adrenergic activity in man. For experimental and physiopathological use, the metabolic alteration induced by a short submaximal muscular work is negligible for most adrenergic compounds, except for MN and NMN, the amounts of which are slightly modified.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Long-term hypoxia increases the number of norepinephrine-containing glomus cells in the rat carotid body: a correlative immunocytochemical and biochemical study.

A group of adult rats was divided into two subgroups: one was submitted to long-term normobaric hypoxia (10% O2, two weeks) while the other (control group) was kept in the same room, breathing air. Animals from each subgroup were used to study either the norepinephrine content of the carotid body by high pressure liquid chromatography or to localize norepinephrine-containing structures using an immunocytochemical procedure (peroxidase-labelled antibodies on cryostat sections). The biochemical study showed, as expected, a large increase in carotid body norepinephrine content (19-fold) and turnover (ten-fold) in hypoxic rats. The immunocytochemical study revealed only a few norepinephrine-immunopositive glomus cells in sections through the carotid body of normoxic rats, whereas the carotid body of hypoxic rats showed a very large number of norepinephrine-positive glomus cells. This increase was quantified, using an image analyser, and it was found to constitute a 61-fold increase in the number of immunopositive profiles per section and a 29-fold increase in the immunopositive profile area/section area ratio. It is concluded that long-term hypoxia increases rat carotid body norepinephrine content by inducing norepinephrine synthesis in glomus cells in which this amine was not detectable previously, before hypoxia.

Animals↗
PubMedDate not supplied

[Selective study of sulfate and glucuronide conjugates of urinary MHPG in nervous depression. Peripheral and central influences].

The determination of urinary MHPG (3-methoxy-4-hydroxyphenyl glycol) has been extensively performed to confirm the noradrenergic hypothesis of some depressions. However, owing to the double origin, central and peripheral, of this norepinephrine metabolite, the validity of total MHPG assay as an index of central noradrenergic activity may be challenged. MHPG exists in human urine in two conjugated forms, at equal amounts: sulfate and glucuronide. A number of arguments suggest that MHPG sulfate and MHPG glucuronide respectively reflect central and peripheral norepinephrine metabolism. In this work, we have selectively estimated both MHPG conjugates in 24 h-urine samples of 36 severely depressed women in view to assess the extent and frequency of central or/and peripheral norepinephrine dysfunction. On the basis of MHPG sulfate and glucuronide values, we conclude that in the examined population (6 endogenous, 19 neurotic, 11 reactive depressions) about 80% of patients exhibited a central NE functional deficit, and many of them had also a diminished sympathetic activity. Clinical symptoms related to psychic factors (melancholia) or associated to sympathetic activity changes (anxiety, retardation) respectively alter sulfate or glucuronide MHPG excretion. These data altogether validate the concept of the independent origin of the two MHPG conjugated and show that their selective assay is able to provide a more satisfactory reflection of the psychobiological state in depressed patients than total MHPG determination.

Adult↗
PubMedDate not supplied

[Effect of training on plasma levels of catecholamines on the course of submaximal exercise].

The effect of a 22.5 week training program on the fuel-hormone response to prolonged (1 h) high intensity (85% maximal aerobic power, MAP) of six male subjects was studied. The training program consisted of pedalling 1 h per day, four days a week, a bicycle ergometer at 80% of their MAP. It resulted in a 14.3% increase in Vo2 max (P less than 0.01). Training did not significantly alter the RQ neither the blood glucose and lipid values measured at the end of a 1 h exercise requiring 85% of Vo2 max. At the end of the exercise blood level of norepinephrine was unchanged; in contrast, that of epinephrine was significantly (35%; P less than 0.01) reduced at the end of training. These results lead to the conclusion that during high intensity submaximal exercise there is no consistent relationship between the epinephrine blood level and mobilization or metabolic utilization of energy substrates in trained subjects.

Adult↗
PubMedDate not supplied

Effect of hemilabyrinthectomy on monoamine metabolism in the medial vestibular nucleus, locus coeruleus, and other brainstem nuclei of albino and pigmented rats.

We compared in albino and pigmented rats the early effect of unilateral labyrinthectomy (UL) on the concentrations of monoamines (norepinephrine, dopamine, serotonin) and their respective metabolites--3-methoxy,4-hydroxyphenylglycol (MHPG), 3,4-dihydroxy-phenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5HIAA)--in medial vestibular nuclei (MVN), locus coeruleus, raphe dorsalis, and cochlear nuclei. The study was conducted 6 hours after UL in both strains, differing by the functional optokinetic responses of their central vestibular neurons and the time-course of their vestibular compensation. The results show that the monoaminergic changes are different in the two rat strains. In the MVN of albino rats, there was a bilateral increase of MHPG and an ipsilateral increase of dopamine suggesting activation of norepinephrine synthesis and metabolism, whereas no such changes were observed in the MVN of pigmented rats. On the other hand, the simultaneous increase of norepinephrine and DOPAC observed in the contralateral locus coeruleus of albino rats suggested enhanced norepinephrine synthesis, whereas in pigmented rats the decreased norepinephrine content found in the ipsilateral locus coeruleus might reflect an earlier strong stimulation of NE release. These biochemical results confirm the relevant role of locus coeruleus noradrenergic innervation in vestibular compensation and also point out the involvement of norepinephrine of the MVN in the early stages of this process. The different strain-related noradrenergic responses observed on the 6th hour suggest that the involvement of central norepinephrine, particularly from locus coeruleus innervation, may be more crucial and more sustained in the albino than in pigmented rats. No serotonin and 5HIAA changes were found in either brainstem nuclei of albino rats. In contrast, the increase of the ratio 5HIAA/5HT observed in raphe dorsalis, in ipsilateral locus coeruleus, and in both sides of MVN of pigmented rats suggested that UL induced an extended and enhanced utilization of 5HT in this strain.

Albinism↗