Hypolipemic effects of histamine is due to inhibition of VLDL secretion from the liver: involvement of both H1 and H2-receptors

Metabolic benefits of novel histamine H3 receptor ligands in the model of excessive eating: The importance of intrinsic activity and pharmacokinetic properties

AIMS

One of the therapeutic approaches in the treatment of obesity is the use of histamine H3 receptor ligands. Histamine plays a significant role in eating behavior because it causes a loss of appetite and is considered to be a satiety signal released during food intake.

MATERIAL AND METHODS

Histamine ligands were selected based on the preliminary studies which included determination of intrinsic activity and selected pharmacokinetic parameters. Female Wistar rats were fed palatable feed for 28 days and simultaneously the tested compounds were administered intraperitoneally at a dose of 10 mg/kg b.w./day. Rats' weight was evaluated daily and calories intake was evaluated once per week. At the end of experiment insulin and glucose tolerance tests was performed. Plasma levels of cholesterol, triglycerides, leptin, insulin, glucose, C-peptide and CRP were also determined. In order to rule out false-positive results the influence of tested compounds on spontaneous activity of rats was monitored.

RESULTS

Animals fed palatable feed and treated with KSK-61 or KSK-63 compounds showed the slowest weight gain which was comparable to the one observed in control animals. Both compounds with the highest pharmacological activity have also similar pharmacokinetic properties with quite long half-life and high volume of distribution indicating that they can freely cross most biological barriers. Some compounds, especially KSK-63, compensated for metabolic disorders.

CONCLUSION

The presented study proves that search among the active histamine H3 receptor ligands for the new therapeutic agents to treat obesity is justified. Compounds KSK-61 and KSK-63 can be considered as the leading structures.

Fixed-time and continuous assays of very-low-density lipoprotein secretion rate from rat liver: mean vs. instantaneous velocity

Aim of the study

The secretion rate of triglyceride from rat liver is assayed by the measurement of triglyceride accumulation in plasma when its clearance is inhibited. The aim of the study was to measure and compare the secretion rate of triglyceride from rat liver by two methods of fixed-time and continuous assays.

Material and methods

A single dose of 200 mg of poloxamer-407 (P-407) was injected i.p. into starved male rats. The secretion rate of triglyceride was measured by fixed-time and continuous assays.

Results

The time course for the changes of serum triglyceride following injection of P-407 showed three distinct phases: a lag period of about 30 minutes, a linear increase in serum triglyceride that lasted more than 4 hours, and a slight decline of triglyceride accumulation that lasted about 24 hours. The mean rate of triglyceride secretion was 234.1 ±9.6 mg/dl/h during the linear phase. The linear phase was divided into five time protocols of 240, 180, 120, 60, and 30 minutes and the secretion rate was measured at three points of time in each protocol. The mean rate of triglyceride secretion was 3.91 ±0.15, 3.83 ±0.16, 3.76 ±0.29, 3.57 ±0.43 and 3.13 ±0.34 mg/dl/min in these protocols respectively. In the kinetic assay, the change in the absorbance per three successive five minutes (ΔA/Δt) was measured and the secretion rate was calculated as 3.82 ±0.11 mg/dl/min.

Conclusions

The rate of triglyceride secretion can be measured by both fixed-time and kinetic assays and was about 3.82 ±0.11 mg/dl/min. The results of the two methods are more corresponded as the mean and instantaneous velocity respectively.