• Archives of Pharmacal Research
• /
• v.22 no.2
• /
• pp.113-118
• /
• 1999

Previous work in our laboratory has shown that the N-methyl-D-aspartate (NMDA) receptor antagonists, AP-5, CPP, MK-801, ketamine, dextrorphan and dextromethorphan cause a pronounced enhancement of 5-hydroxytryptamine (5-HT)-induced head-twitch response (HTR) in intact mice, suggesting the involvement of NMDA receptors in the glutamatergic modulation of serotonergic function at the postsynaptic $5-HT_{2}$ receptors. The purpose of this study was to extend our previous work on the behavioral interaction between glutamatergic and serotonergic receptors. In the present study, both competitive (AP-5 and CPP) and noncompeti-tive (MI-801, ketamine, dextrorphan and dextromethorphan) NMDA receptor antagonists markedly enhanced 5-HT-induced selective serotonergic behavior, HTR, in p-chlorophenylalanine (PCPA)-treated mice which were devoid of any involvement of indirect serotonergic function, to establish the involvement of the NMDA receptor in 5-HT-induced HTR at the postsyaptic $5-HT_{2}$receptors. In addition, the enhancement of 5-HT-induced HTR was inhibited by a dopamine agonist, apomorphine, NMDA receptor antagonist, NMDA and a serotonin $5-HT_{2}$receptor antagonist, cyproheptadine, in PCPA-treated mice. Therefore, the present results support our previous conclusion that the NMDA receptors play an important role in the glutamatergic modulation of serotonergic function at the poststynaptic $5-HT_{2}$ receptors.

• Journal of Nutrition and Health
• /
• v.14 no.2
• /
• pp.59-70
• /
• 1981

The objective of this study is to induce the primary characteristics of phenylketonuria in infant rats during the first 2 weeks after birth. The critical biochemical parameter in the development of phenylketonuria is the elevation of plasma phenylalanine while tyrosine is maintained at a relatively low level. A PKU-like condition was induced in infant rats during the first 2 weeks after birth using a modification of our previously published procedure for the development of a temporary (1 to 3 days) PKU-like condition. Phenylalanine was administered by stomach intubation every 6 hours (starting at 6:00 a.m.) at a dose level of 400mg per kg body weight (after birth-day 2 thru 5) and 500mg per kg body weight (day 6 thru 14). Amethopterin was given at 0.00625 or 0.0125mg per kg body weight (day 3 thru 14) and p-chlorophenylalanine at 50 mg per kg body weight (day 5 thru 14) at 9:00 a.m. and 9:00 p.m. At the times measured (6,10 and 14 days) plasma phenylalanine/tyrosine (P/T) ratios were elevated from a normal value of the or less to values ranging from 6 to 15. During the second week after birth a staggering gait, abnormal stance and decreased social behavior were also observed. None of these PKU-like characteristics were apparent in the three control groups receiving (a) no phenylalanine or inhibitors, (b) phenylalanine alone, or (c) inhibitors alone. The establishment of these primary biochemical characteristics of phenylketonuria by stomach intubation of phenylalanine and a combination of low dose levels of enzyme inhibitors to infant rats provides an experimental system which should he valuable for extensive biochemical, histological and behavioral studies in phenylketonuria.

• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.2
• /
• pp.133-138
• /
• 2001

In the present study, we investigated the effect of pretreatment of p-chlorophenylalanine (PCPA), inhibitor of serotonin synthesis, on lipopolysaccharide (LPS)-induced anorexia in rats. First of all, effects of PCPA injection on food intake and body weight in rats were investigated. During 4 days of PCPA injection (300 mg/kg BW once a day), food intake was decreased by 33% and daily gain in body weight was inhibited compared with controls. Twenty-four hours after last PCPA injection, food intake and gain in body weight returned toward almost normal. Pair-feeding to PCPA (PCPAP) injection revealed that body weight of rats in PCPA group was not different from rats in PCPAP groups. To quantify the effects of LPS on food intake and body weight, we administered varying doses $(10,\;100,\;500\;{\mu}g/kg\;BW)$ of LPS to rats. LPS induced a reduction of food intake and weight loss in a dose dependent manner compared with controls. To evaluate the effects of PCPA pretreatment on LPS injection, rats were treated with PCPA for 4 days (300 mg/kg BW once a day), which was followed by LPS injection for 2 days $(500\;{\mu}g/kg\;BW\;once\;a\;day)$ (PCPA+LPS group), while rats in LPS group had injections with normal saline instead of PCPA for 4 days, which was followed by LPS administration. Rats in control group received 0.9% NaCl for 6 days. LPS decreased food intake by 80% and inhibited gain in body weight, while PCPA pretreated rats showed normalized food intake and gain in weight during the days of LPS injections compared with controls. In conclusion, pretreatment of PCPA prevented LPS-induced anorexia.

• Journal of Ginseng Research
• /
• v.46 no.6
• /
• pp.819-829
• /
• 2022

Background: Anxiolytic properties of Korean Red Ginseng (KRG) have been previously reported. However, the exact mechanism(s) of action remains to be elucidated. The present study investigated the effect of KRG on immobilization-induced anxiety-like behaviors in mice and explored the involvement of the serotonin and GABA systems and BDNF in the anxiolytic action. Methods: Mice were orally administered with KRG (200 mg/kg/day) for 4 weeks and immobilized once daily for 2 h. p-Chlorophenylalanine (p-CPA) was intraperitoneally injected on day 22-28, and flumazenil or bicuculline was injected on day 25-28. After behavioral evaluations, brains were dissected for biochemical analyses. Results: KRG improved immobilization-induced anxiety-like behaviors in mice, as assessed by the elevated plus maze (EPM) and marble burying tests (MBT). The anxiolytic effect of KRG was comparable to that of fluoxetine, a reference drug clinically used for anxiety disorders. A serotonin synthesis inhibitor, p-CPA, blocked the effect of KRG in the EPM and MBT, indicating the requirement of serotonin synthesis for anxiolytic action. In addition, the anxiolytic effect of KRG was inhibited by bicuculline (a GABA_A antagonist) in MBT, implying the involvement of GABA transmission. Western blotting analyses revealed that KRG upregulated the expression of tryptophan hydroxylase and GABA_A receptor in the brain, which was blocked by p-CPA. Enhanced BDNF expression by KRG in the hippocampus was also indicated to mediate the anxiolytic action of KRG in immobilized mice. Conclusion: KRG exhibited the anxiolytic effect in immobilized mice by multiple mechanisms of action, involving enhanced serotonin and GABA transmissions and BDNF expression.

• The Korean Journal of Pharmacology
• /
• v.26 no.1
• /
• pp.1-6
• /
• 1990

We established an in vitro system of central serotonergic neurons by culturing dissociated rat embryonic (El4) brainstem cells to 14 days in vitro and monitored the serotonergic neuronal growth by measuring 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents in the cells with hish performance liquid chromatography with electrochemical detection (HPLC-EC). We studied also tile effects of various drugs on the contents of 5-HT and 5-HIAA, confirming in vivo reports. The 5-HT content (13 ng/mg protein) and 5-HT turnover rate (17 pmol/mg protein/h) at 14 days in vitro were in good agreement with those reported in the adult rat brain. The 5-HT content was more easily depleted with p-chlorophenylalanine, a tryptophan hydroxylase inhibitor than with NSD 1015 (3-hydroxybenzylhydrazine), an aromatic L-amino acid decarboxylase (AADC) inhibitor. Incubation of the cultures with tryptophan or 5-hydroxytryptophan increased the rate of serotonin formation implying that neither tryptophan hydroxylase nor AADC is saturated with its amino acid substrate in this in vitro system . The 5-HT content was depleted by reserpine. The 5-HT and 5-HIAA contents were increased and decreased, respectively, by monoamine oxidase inhibitors. All the above results indicate that the biochemical properties of the central serotonergic neurons in this culture system reflect reliably those of central serotonergic neurons in vivo. We suggest that measuring 5-HT and 5-HIAA contents in the primary cultured dissociated brainstem-cells with HPLC-EC is useful in the study of pharmacology as well as toxicolgy of the central serotonergic neurons.

• Proceedings of the KSAR Conference
• /
• 2001.03a
• /
• pp.51-51
• /
• 2001

Cocaine and amphetamine-regulated transcript (CART) is a satiety factor that is regulated by leptin. It was reported that the mice intracerebroventricularly injected with CART showed behavioral changes resembled with the typical behavioral alterations found in the mice carrying disorders in the brain serotonergic (5-HT) system. Hence, this study was conducted to find out the relationships between CART and 5-HT. We first examined the mRNA levels of CART after the injections of para-chlorophenylalanine (pCPA, 300 mg/kg i.p., single injection or daily for three consecutive days) in the rat brains by in situ hybridization using the mouse CART cDNA probe cloned in our laboratory. Systemic administrations of pCPA, a potent inhibitor of tryptophan hydroxylase, the rate limiting enzyme of 5-HT biosynthesis, acutely depletes the brain 5-HT transporter (5-HTT) in the dorsal raphe nucleus (DRN), which reuptakes terminal 5-HT. Results indicated that the mRNA level of CART significantly decreased in the arcuate nucleus, paraventricular nucleus, and lateral hypothalamic nucleus by three days of daily injection with pCPA with no noticeable change detected 24 hrs after the single injection. The message levels of 5-HTT in DRN decreased in both single and three days of injections. Secondly, to investigate whether CART affect to 5-HT, mouse genomic CART gene, which is consist of 3 exons and 2 introns and mouse neurofilament light (NF-L) chain promoter were cloned. Then, we constructed neuron specific expression vector, which was transfected into HeLa cell using lipid-mediated transfection system. Expression of GFP and CART linked to NF-L-chain promoter in the transfected HeLa cell were detected by using fluorescent microscope and RT-PCR. These results confirmed normal expression of DNA constructs in vitro. Then, to increase brain specific expression of CART in vivo transgenic mice carrying CART gene controlled the deleted NF-L-chain promoter were generated by the DNA microinjection into pronuclei of fertilized embryos. Transgenic mice were detected by Southern blot. Further study is necessary to examine CART expression and 5-HTT in these transgenic mice. Therefore, these results suggest that there maybe a positive molecular correlation between CART and 5-HT in responding to the stimuli.