Behavioural changes on diet selection and serotonin (5-HT) turnover in rats under pizotifen treatment

The effects of pizotifen on protein and carbohydrate self-selection in rats over a seven-day period, and on 5-HT turnover was studied. Four groups of male Wistar rats were individually caged and ad lib fed with a standard (SD) and (50%) carbohydrate-enriched diet (CED), sweet (diet group I) or not (diet group II). Food intake was measured daily 4 hr after IP injection of pizotifen (2.5 mg/kg) or vehicle. 5-HT and 5-HIAA in the hypothalamus (Hy), striatum (St) and hippocampus (Hi) were assayed on the 8th day of the experiment. Pizotifen increased the consumption of SD. The absolute intake of CED remained totally and daily unchanged, while the percentage proportion was reduced. Total food intake was increased by the drug which seemed to affect the proportion rather than the absolute amounts of carbohydrate and protein consumed. This effect was independent of the carbohydrate taste. There was a decrese of 5-HT levels in the Hi, while 5-HIAA/5-HT ratio was increased in the Hy and in the Hi of animals that consumed sweet carbohydrate. The above data suggest a role of pizotifen on 5-HT central metabolism and diet selection and support the view that changes of 5-HT metabolism in the Hy and Hi are responsible for protein selection and the regulation of SD/CED ratio, but they cannot explain drug's effect on total food intake. © 1990

Rapid effects of 17 beta-estradiol and progesterone on sheep visceral and parietal pleurae via a nitric oxide pathway

We investigated the effects of 17beta-estradiol and progesterone on transepithelial electrical resistance (R-TE) in sheep visceral and parietal pleurae. Specimens of intact pleurae from adult female sheep were used. The samples were transferred to the laboratory within 30 min after death of the animal in a Krebs-Ringer solution at 4degreesC. The pleura was then mounted as a planar sheet in Ussing-type chambers, and electrical measurements were made. There was an increase in R-TE in all of the samples examined after addition of 17beta-estradiol and progesterone in visceral and parietal pleurae. This increase was rapid within 1 min, lasted for similar to15 min, returned to the basal level within 30-45 min, and was dose dependent. Tamoxifen, an estrogen receptor antagonist, did not significantly eliminate the effect of 17beta-estradiol. Furthermore, no steroid receptors were identified in cytosolic preparations of visceral and parietal pleura with ligand binding assays. The estrogen- and progesterone-induced increase in R-TE in both visceral and parietal pleurae was affected by addition of an inhibitor of nitric oxide synthase. Indeed, previous administration of N-omega-nitro-L-arginine methyl ester prevented the increase in R-TE by 17beta-estradiol and progesterone. These results suggest that 17beta-estradiol and progesterone induce an increase in R-TE in both visceral and parietal pleura and thus alter the transepithelial permeability. The effect of steroids may be accounted for by rapid release of nitric oxide in pleura