HPLC determination of brain biogenic amines following treatment with bispyridinium aldoxime K203.

Effect of a new acetylcholine-esterase reactivator, K203 as a new potential antidote in organophosphate intoxications was studied on dopamine (DA), homovanillic acid (HVA), serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels in seven brain regions (cerebellum, spinal cord, hippocampus, hypothalamus, striatum, medulla oblongata and frontal cortex) of rats by an optimized and validated HPLC method. No significant change in brain level of these neurotransmitters was found either 15 or 60 min following treatment. However, when 5-HIAA/5-HT ratios were calculated as measure of turnover, significant decreases were found in the cerebellum, hippocampus, hypothalamus and the frontal cortex 15 min following K203 administration, but after 60 min only in the frontal cortex.

Medicinal chemistry of antimigraine drugs.

Migraine is one of the most frequent neurological disorder with high impact on the quality of life. Primary headaches such as migraine are pathophysiologically complex disorders. The concept of the trigeminovascular system dysfunction in migraine has led to a number of drug discoveries dramatically changing the treatment options. Acute and prophylactic therapy targeting either the trigeminovascular system or central structures involve several groups of drugs with peculiar medicinal chemistry. In the proposed review up to date concept of treatment strategy, medicinal chemistry data of the drugs used will be summarized. The present review gives detailed information on drugs effective in aborting migraine attacks (by inhibiting prostanoid synthesis, are agonists of serotonin 5-HT1B/D receptors, on the recently introduced CGRP-receptor antagonists) and the drugs recommended for prophylactic treatment (selected beta-adrenergic receptor antagonists, Ca-channel inhibitors, antiepileptics, antidepressants). The pharmacokinetics, fate in the body (absorption, distribution, metabolism, excretion) and significant pharmacological effects as well as the recent bioanalytical methods for their determination are presented.

Effect of a single neonatal oxytocin treatment (hormonal imprinting) on the biogenic amine level of the adult rat brain: could oxytocin-induced labor cause pervasive developmental diseases?

Perinatal single-hormone treatment causes hormonal imprinting with lifelong consequences in receptor-binding capacity, hormone production as well as in social and sexual behavior. In the present experiments, newborn rats were treated with a single dose of oxytocin, and the levels of biogenic amines and their metabolites were studied in 8 different brain regions and in the sera when the male and female animals were 4 months old. Both dopaminergic and serotonergic neurotransmission was found to be significantly influenced. The levels of 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindole acetic acid metabolites decreased in the hypothalamus and striatum. Dopamine, serotonin, norepinephrine, and 5-hydroxytryptophol levels were hardly altered, and there was no difference in the epinephrine levels. The results show that dopamine and serotonin metabolism of hypothalamus and striatum are deeply and lifelong influenced by a single neonatal oxytocin treatment Oxytocin imprinting resulted in decreased dopamine turnover in the hypothalamus and decreased serotonin turnover in the hypothalamus, medulla oblongata, and striatum of females. As the disturbance of brain dopamine and serotonin system has an important role in the development of pervasive developmental diseases (eg, autism) and neuropsychiatric disorders (eg, schizophrenia), the growing number of oxytocin-induced labor as a causal factor, cannot be omitted.

Study on medicinal chemistry of K203 in wistar rats and beagle dogs.

K203 is an experimental bis-pyridinium mono-aldoxime type cholinesterase reactivator of potential use in organophosphate/ organophosphonate poisoning. Pharmacokinetics of K203 were examined in Wistar rats and beagle dogs using ion-pair HPLC. Serum and cerebrospinal fluid concentrations of K203 were determined using ion-pair reversedphase chromatography on octadecyl silica column. HPLC with ultraviolet detection was used for determination of serum concentration of K203 higher than 0.1 µg/mL while its low concentrations in cerebrospinal fluid required electrochemical detection (0.015 through 4 µg/mL range). In rats the serum levels of K203 followed zero order pharmacokinetics from 15 to 120 minutes post administration. Zero order pharmacokinetics was also observed in beagle dogs after low dose (15 µmol/kg) of K203 administration. High dose administration (250 µmol/kg) led to subsequent hindered elimination from both cerebrospinal fluid and serum.

Effect of perinatal stress on the biogenic amine neurotransmitter level of the adult rat's brain.

The amount of biogenic amines (dopamine and serotonin) and their metabolites (DOPAC, HVA, 5-HIAA, and 5-HTOL) in five regions of the brain (frontal cortex, hypothalamus, hippocampus, striatum, and brainstem) was studied in the male and female offspring of control and perinatally (48 h before birth or 48 h after birth) food and water deprived dams, when they were three months old, by using HPLC-EC determination. The increase of amine or metabolite level was dominant (19 values increased and 10 decreased related to control). Before-birth stress caused increase in 9 case and only 2 decreased, while in the case of after-birth stress 10 increased and 8 decreased. However, though there is no possibility to decide an exact tendency of direction, the after-birth stress (transmitted by milk) has more expressed effect. Striatum and brainstem were the most touched regions. There was a gender dependence with the dominance of males, except striatum. Blood plasma nociceptin level was also studied and there was a significant elevation in males after pre- and postnatal deprivation, while in females only after postnatal deprivation. The importance of the results in correlation with other stress effects is discussed.

Pyridinium aldoxime analysis by HPLC: the method for studies on pharmacokinetics and stability.

Reversed-phase separation of various pyridinium aldoximes requires a certain concentration of ion-pairing agent, as their chemical structures contain two quaternary amines in the pyridinium ring. Adequate mobile phase is scouted on the basis of retention of pyridinium aldoxime (using the graph of k' versus concentration of an ion-pairing agent) compared to the chromatogram of the background peaks originated from the homogenate. Change in the ion-pairing agent concentration was more expressed for the elution of K-203 than that of the background peaks from the serum, brain and cerebrospinal fluid. Stability of K-203 was investigated using HPLC. Determination of K-203 in tissue samples requires homogenization using either trichloroacetic acid or perchloric acid. Fast degradation takes place at acidic pH. Adjusting pH to neutral in the possible shortest time frame helps to avoid degradation. Degradation of K-203 was easily followed by HPLC separation and monitoring the elution with an ultraviolet absorbance detector at 276 nm. Amperometric detection indicates only the decrease of K-203 content.