R. Laufer

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.

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.

TLC of Quaternary Pyridinium Aldoximes, Antidotes of Organophosphorus Esterase Inhibitors

Quaternary pyridinium aldoximes have been analyzed by thin-layer chromatography. Their separation was adequate when silica plates were used with a mobile phase with a high water content. As a consequence of their limited migration, reversed-phase TLC was not appropriate for determination of the lipophilicity of quaternary pyridinium aldoximes. Displacement TLC of some quaternary pyridinium aldoximes is, nevertheless, possible using silica as stationary phase with water–acetone–hydrochloric acid mobile phases. Normal-phase TLC with different concentrations of organic modifier gave a series of RM values for the pyridinium aldoximes. Approximation of the different plots of RM against organic modifier concentration to straight lines afforded RM,0 values and the slopes of the lines. The RM,0 values and the slopes both serve as indicators of the hydrophilic character of the compounds.

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.

Monitoring by HPLC of chamomile flavonoids exposed to rat liver microsomal metabolism

Three major flavonoid chamomile components (quercetin, apigenin-7-O-glucoside and rutin) were subjected to oxidative metabolism by cytochrome P-450 of rat liver microsomal preparations. Changes over time in their respective concentrations were followed using reversed-phase HPLC with UV detection. No clean-up had to be applied as only the specific flavonoid had to be separated from the background components originating from the rat liver microsome. Neither the concentration of apigenin-7-O-glucoside nor that of the diglycoside rutin decreased during one hour of exposure to rat microsomal treatment. In contrast, the concentration of quercetin, a lipophilic aglycon, decreased. Our analytical HPLC results complement the in silico calculated lipophilicity (logP) of these compounds; the relatively high lipophilicity of quercetin appears to predispose it to oxidative metabolism in order to decrease its fat solubility. In contrast the much less lipophilic compounds apigenin-7-O-glucoside and rutin were resistant in vitro to microsomal treatment.

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.