Biomedical subjects

P Alster

Publications and source records attributed to P Alster.

39 records · Page 3Linked to original sources

PubMed1980

Effect of nicotine on the formation of prostaglandins in the rabbit kidney.

The effect of nicotine on the bioformation of prostaglandins (PG) in the rabbit kidney was investigated. Rabbit kidneys were homogenized and the low-speed supernatant was incubated with 14C-labelled arachidonic acid (14C-AA), a PG precursor. Nicotine was added to the incubations to produce final concentrations of 5 x 10(-7) M to 5 x 10(-4) M. Control incubations without nicotine were also performed. 14C-PG formed were separated and evaluated on thin layer radiochromatography. In control experiments 14C-labelled PGD2, PGE2 and PGF2 were formed, the relative amounts in between them being 16, 31 and 53%, respectively. Nicontine dose-dependently depressed the formation of all PG formed in the kidney. At 5 x 10(-7) M the formation of 14C-PG was depressed to 45-80% of control and at a concentration of 5 x 10(-4) M it was depressed to 40% or less of control. It is concluded that nicotine elicits an overall depressive effect on the rabbit kidney formation of PG, probably by inhibiting cyclo-oxygenation of AA.

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PubMedDate not supplied

Dissociation of oxytocin effects on body weight in two variants of female Sprague-Dawley rats.

As a counterpoint to studies that make a case for the use of oxytocin in short-term inhibition of food intake, the aim of the present study was to determine whether the peptide facilitates weight gain in female rats in a more long-term perspective. Two different variants of females Sprague-Dawley rats were used. The two variants differed in daily weight gain (0.38 g/day vs. 1.41 g/day during 28 days), and were designated slowly and rapidly growing rates (SGR and RGR) respectively. Oxytocin 1 mg/kg given s.c. to SGR for a five-day period increased weight gain significantly in comparison to a previous five-day period with NaCl-treatment (18.0 g/5 days versus 5.0 g/5 days; p < 0.01). In a separate study, oxytocin 1 mg/kg given for four days increased weight gain significantly in SGR versus saline-treated controls (7.5 g/4 days versus 1.6 g/4 days; p < 0.05). The weight-difference persisted six days later (p < 0.001). The weight increase of oxytocin occurred only during estrus (p < 0.05) and was not accompanied by any measurable increase in food intake. In RGR, oxytocin-treatment decreased food intake significantly (p < 0.001) and tended to decrease weight gain, although not significantly. The SGR and RGR also had different endocrine profiles with, for example, twice as high oxytocin (p < 0.01) and insulin levels (p < 0.01) in RGR compared to the SGR. These data suggest that oxytocin influences weight gain and food intake differently in the two variants of Sprague-Dawley rats, perhaps depending on factors such as endocrine profile and oxytocin sensitivity.

Animals↗

PubMedDate not supplied

Plasma cholecystokinin concentrations in 3-day-old lambs: effect of the duration of fasting preceding a sucking bout.

Cholecystokinin (CCK) is a regulatory peptide released into the circulation after the ingestion of food. Our knowledge concerning the factors affecting its pattern of secretion in the mammalian neonate is scanty. Therefore, in this work we studied plasma concentrations of CCK in 3-day-old lambs after a sucking bout that followed either a short (2 h) or a long fasting period (9 h). Plasma concentrations of CCK were measured by radioimmunoassay in blood samples collected from jugular veins 10 min before, immediately after a sucking bout, and then at 10-min intervals during the following hour. In the first experiment a period of fasting of 2 h before allowing the lambs to suck did not lower the levels of CCK. On the other hand, a significant decrease was recorded 10 min after feeding ended. Between 20 and 50 min after the end of sucking, the mean CCK concentration rose back to the pre-feeding level before decreasing again at 60 min. In the second experiment a period of fasting of 9 h, on the other hand, significantly lowered the levels of CCK. Plasma levels also tended to decrease immediately after sucking was ended. This was followed by a substantial rise and levels remained high during the rest of the sampling period. It was concluded that the decrease recorded immediately after a sucking bout could be due to an inhibitory effect of the oral phase while the following rise reflected the stimulatory effect of milk nutrients on intestinal CCK-producing cells.

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