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Biomedical subjects

M Bonnet

Publications and source records attributed to M Bonnet.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

Neuropharmacological study of aged MAM-treated rats.

After evaluation of activity in an open field, norepinephrine (NE), serotonin (5HT), 5-hydroxyindolacetic acid (5HIAA), homovanillic acid (HVA), and choline acetyltransferase (CAT) were investigated in cortex of 26-month-old rats poisoned with methylazoxymethanol (MAM) as compared to control rats of the same age. NE and 5HT concentrations showed a marked increase, but levels were normal when expressed as total content, just as in MAM-exposed young adults. Concentrations of 5HIAA were also increased but to a lesser extent than 5 HT. Aged MAM rats did not show any modification of spontaneous activity although hyperactivity is characteristic of young adults exposed to MAM. Together with this behavioral observation, a significant decrease in total HVA content was measured. Because HVA levels seem correlated with activity in MAM-exposed rats, we speculate that the behavioral abnormality recovers in old age. Total CAT activity was also reduced. These results indicate that the neurochemical pattern of young adult MAM-poisoned rats is conserved in aged rats except for some changes in the dopaminergic and cholinergic systems.

Aging↗
PubMedDate not supplied

Messenger RNAs encoding lipoprotein lipase, fatty acid synthase and hormone-sensitive lipase in the adipose tissue of underfed-refed ewes and cows.

The mechanisms involved in the nutritional regulation of genes encoding lipogenic (lipoprotein lipase (LPL) and fatty acid synthase (FAS)) and lipolytic (hormone-sensitive lipase (HSL)) enzymes were investigated by comparing the levels of the corresponding mRNAs in the adipose tissue (AT) of underfed or underfed-refed ewes and cows. Refeeding sharply increased LPL and FAS activities (19-25- and 6-8-fold, respectively) and moderately increased (2-4 fold) the activities of glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME) and glycerol-3-phosphate dehydrogenase (G3PDH). Northern blot analysis revealed three LPL transcripts and a single FAS transcript in cow and ewe AT. A single HSL mRNA was detected in cow AT and two transcripts in ewe AT. Refeeding sharply increased LPL and FAS mRNA levels, while restriction slightly increased (cows) or had no effect (ewes) on the HSL mRNA levels. This suggests that nutritional factors regulate sharply the expression of LPL and FAS genes by pretranslational mechanisms, but less clearly that of HSL gene.

Adipose Tissue↗
PubMedDate not supplied

Effects of photoperiod and feeding level on perirenal adipose tissue metabolic activity and leptin synthesis in the ovariectomized ewe.

Leptin is secreted by adipose tissue and plays a pivotal role in regulating both body energy homeostasis and reproductive function in rodents. Among livestock, sheep is a seasonal breeder whose reproductive period is initiated by short daylength. We show that plasma leptin and leptin gene expression in perirenal adipose tissue were decreased when ovariectomized Lacaune ewes were exposed to short days (8 versus 16 h light/d). This effect of the photoperiod occurred despite the nutritional status, with leptin levels lower in underfed than in refed ewes, and without significant changes in perirenal fat mass and adipocyte size. Plasma prolactin and leptin followed a similar pattern suggesting a relationship between the two hormones. These findings indicate, for the first time, that adipose tissue leptin is modulated by daylength independently of food intake, body fatness and gonadal activity. Furthermore, plasma non-esterified fatty acids of underfed ewes subjected to short days were more elevated than for underfed ewes on long days. On the other hand, refed ewes placed under long daylength tended to have a higher adipose tissue lipogenic activity than refed ewes on short days. We propose that these adaptations of leptin production and lipogenic activity with long photoperiod are of physiological significance for body fat deposition, which naturally occurs during long days when food is abundant. Conversely, a low leptin level during short days may enhance the sensitivity to food deprivation during the natural reproductive season, where any food shortage would decrease plasma leptin under a threshold critical for reproduction. Furthermore, in this situation, the observed enhanced ability to mobilize body fat may be related to the necessity to cope with energy shortage.

Adipose Tissue↗
PubMedDate not supplied

[Areolar atrophy of the macula].

The article is a general review of central areolar choroidal dystrophy based on 24 cases, some of them followed from one year up to six years. Two major points are discussed: the etiology and the natural course. The disease is believed by the author not to be an etiological entity for, if it can occur as a primary maculopathy, it is more often the ultimate stage of another heredo macular degeneration. The visual prognosis depends more upon the location of the lesion than upon its size. Of course the visual prognosis is poor when the atrophy involves the center of the macula, but it is good, at least during several years, when the very center of the fovea is spared off.

Adult↗