Rats In Various States Research Articles

HISTAMINE: A NEUROTRANSMITTER THAT INFLUENCES FOOD INTAKE?

Brain histamine levels in rats in various states of water balance were raised by blocking histamine catabolism with metoprine. Acute administration of this drug caused a significant reduction in food intake. This finding suggests a possible role of histamine in the regulation of food intake.

Effect of Change of Hepatic Drug-Metabolizing Activity on Plasma Concentrations of Major Metabolites of the New Sleep Inducer 450191-S, a 1H-1,2,4-Triazolyl Benzophenone Derivative

Plasma concentrations of the major metabolites of 450191-S, a new sleep inducer which is a 1H-1,2,4-triazolyI benzophenone derivative, were determined in rats. Under the HPLC conditions employed, several major metabolites were detected in plasma, and thus the plasma concentration-time profiles for these metabolites were checked in rats in various states. When the animals were pre-treated with high doses of 450191-S (200 or 600 mg/kg for 5 or 3 days, respectively) to induce hepatic drug-metabolizing enzymes, plasma concentrations of the metabolites after oral administration of a dose of 200 mg/kg of 450191-S decreased markedly depending on the induced enzyme activity. Pretreatment of rats with phénobarbital also caused decreased plasma levels of metabolites, which were almost the same as those in 450191 -S-pretreatment On the other hand, administration of beta-naphthoflavone to rats led to higher plasma levels of metabolites, and slower elimination compared with those in the control and 450191-S- or phenobarbital-pretreated rats. These results indicate that plasma levels of metabolites are regulated by the drug-metabolizing enzymes in the liver. It also suggests the participation of some specific forms of cytochrome P-450 In the biotransformation of 450191-S and its metabolites.

Effect of change of hepatic drug-metabolizing activity on plasma concentrations of major metabolites of the new sleep inducer 450191-S, a 1H-1,2,4-triazolyl benzophenone derivative.

Plasma concentrations of the major metabolites of 450191-S, a new sleep inducer which is a 1H-1,2,4-triazolyl benzophenone derivative, were determined in rats. Under the HPLC conditions employed, several major metabolites were detected in plasma, and thus the plasma concentration-time profiles for these metabolites were checked in rats in various states. When the animals were pretreated with high doses of 450191-S (200 or 600 mg/kg for 5 or 3 days, respectively) to induce hepatic drug-metabolizing enzymes, plasma concentrations of the metabolites after oral administration of a dose of 200 mg/kg of 450191-S decreased markedly depending on the induced enzyme activity. Pretreatment of rats with phenobarbital also caused decreased plasma levels of metabolites, which were almost the same as those in 450191-S-pretreatment. On the other hand, administration of beta-naphthoflavone to rats led to higher plasma levels of metabolites, and slower elimination compared with those in the control and 450191-S- or phenobarbital-pretreated rats. These results indicate that plasma levels of metabolites are regulated by the drug-metabolizing enzymes in the liver. It also suggests the participation of some specific forms of cytochrome P-450 in the biotransformation of 450191-S and its metabolites.

Alterations in the onset of ovulatory failure and gonadotropin secretion following steroid administration to lightly androgenized female rats.

The present studies were designed to characterize the gonadotropin response to exogenous steroids in neonatally androgenized female rats in various states of reproductive decline. Female rats were androgenized by the administration of a single injection of testosterone propionate (TP) (10 or 100 micrograms) at 5 days of age. Control rats received sesame oil. Treatment with 100 micrograms TP resulted in persistent vaginal estrus (PVE) from the onset of vaginal introitus. Treatment with 10 micrograms TP resulted in a period of regular estrous cyclicity followed by PVE. In the first experiment, all animals were ovariectomized between the ages of 60-85 days and the gonadotropin response to exogenously administered estradiol benzoate (EB) (10 micrograms/100 g BW) and progesterone (P) (2 mg/animal) was determined. When testing began 3 days following ovariectomy, control females exhibited significant (P less than 0.01) afternoon elevations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) following EB, which were further amplified following P. When ovariectomy occurred prior to the onset of PVE (PRE PVE), lightly androgenized females (10 micrograms TP) showed no significant afternoon gonadotropin increase following EB. Following P, phasic LH secretion was present but significantly (P less than 0.01) decreased in amplitude and delayed in onset versus that of control females. When ovariectomy occurred 3 to 4 wk following the onset of PVE, lightly androgenized females (PVE group) as well as fully androgenized females (FAS) (100 micrograms TP) showed no gonadotropin response to steroid priming.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro correlation of glutamine and glutamate renal ammoniagenesis during adaptation.

Renal slices from 191 rats in various states of acid-base balance were investigated for their ability to produce ammonia from both glutamine and glutamate. Under a variety of conditions, in three different type studies, a significantly similar correlation existed between ammonia adaptation from glutamine and glutamate. This relationship was maintained during acute and chronic acidosis and during alkalotic inhibition of renal ammoniagenesis. We conclude from our findings that ammonia adaptation in rats secondary to acute and chronic acidosis is similar, although incomplete during acute acidosis. Our results further support the hypothesis that the rate of glutamate deamination is a major mechanism for overall renal ammonia adaptation in rats during acid-base changes.

Occurrence and properties of 17β-oestradiol receptors in rat brain

The occurrence and properties of 17beta-estradiol receptors in rat b rain are discussed. The numbers of 17beta-estradiol binding sites were measured separately in cytosols from anterior middle and posterior regions of the hypothalamus of adult rats in various states. The ratio of estrogen-specific high affinity binding site concentration in adult cortex-amygdada-hypothalamus was 1:5:11 in mixed cycling females and 1:3:6 in intact males. In 5-day-old rats the diethylstilbestrol (DES) suppressible binding sites were distributed in roughly equal concentration in both brain areas and at levels similar to those found in adult hypothalamus or amygdala. Equibibrium was reached in less than 5 minutes with uterine or hypothalamic cytosol whereas with pituitary cortex or amygdala more than 10 minutes were required. There was a difference in affinity between pituitary cytosol and cytosol from brain region or uterus. There was no difference in affinity between brain regions or between sexes in the neoates. It may be that the apparently lower affinities for estrone or 17beta-estradiol in the DES suppressible binding system is an artefact due to alpha-fetoprotein-like material in the incubates.

The effect of choline on the liver fat of rats in various states of nutrition

The effect of choline on the liver fat of rats in various states of nutrition