G. Ismahan

Urinary phenylethylamine excretion: Gas chromatographic assay with electron-capture detection of the pentafluorobenzoyl derivative

Phenylethylamine was extracted into n-hexane from alkaline urine saturated with sodium chloride, and back-extracted into dilute acid. The extract was freeze-dried and the residue converted to a pentafluorobenzoyl derivative for analysis by gas chromatography on a column of OV-225 with electron-capture detection. Quantification was achieved by adding an internal standard of tolylethylamine to each sample prior to extraction. Output values in normal subjects and in some patients with phenylketonuria and hyperphenylalaninaemia were in agreement with those in some other recent reports.

Activity of catechol-o-methyltransferase in brain regions and adrenal gland during the oestrus cycle.

The activity of the enzyme catechol-O-methyltransferase (COMT) during four different phases of the oestrus cycle were determined. Brain and hypothalamus had highest level of COMT activity during oestrus phase, while at pro-oestrus it was at its lowest level. COMT activity in the adrenal gland was also modified during the four phases with the maximum level at met-oestrus and the minimum at pro-oestrus phase. The results provide evidence to show that COMT in the brain, hypothalamus and the adrenals is markedly affected by changes in physiological status of the female rats and its evolution in brain is different from adrenal gland during the oestrus cycle. The variations in the activity of COMT may be the consequence of modified endocrine activity which takes place naturally during oestrus cycle.

Influence of perinatal adrenalectomy and adrenal demedullation upon development of enzyme catechol-o-methyltransferase in peripheral organs of the rat.

Newborn rats were adrenalectomized at 0 h after birth and the development of enzyme catechol- o -methyltransferase (COMT) in heart, lung, liver and kidney at 3, 5, 10, 15 and 20 days

Comparative effects of hypophysectomy and adrenalectomy upon plasma and adrenal monoamines in pregnant and non-pregnant rats.

1 The influence of hypophysectomy and adrenalectomy upon release and storage of adrenaline and noradrenaline during rat oestrous cycle and pregnancy has been studied.

The influence of hypophysectomy, adrenalectomy, progesterone, oxytocin, and estradiol on the metabolic fate of 3H-epinephrine in central and peripheral regions during late pregnancy

Abstract Variations in the metabolic fate of 3 H-epinephrine during the last days of pregnancy were determined in seven peripheral organs and three brain regions of the rat. Hormonal treatments were performed during Days 19 to 21 after coitus. Hypophysectomy of the pregnant females on Day 17 after coitus increased the transformation of 3 H-metanephrine and 3 H-acid metabolites from tracer epinephrine when compared to Day 21 after coitus. Adrenalectomy produced effects similar to those of hypophysectomy as all the peripheral and central regions except the kidney showed an increased rate of 3 H-acid metabolite formation but the formation of 3 H-metanephrine was increased only in liver, spleen, ovary, uterus, hypophysis, hypothalamus, and brain. Pretreatment with oxytocin decreased the rate of amine metabolism in most of the organs. Progesterone increased the metabolism of tracer epinephrine in the heart, spleen, ovary, hypophysis, and hypothalamus. Estradiol treatment decreased metabolism of 3 H-epinephrine to 3 H-metanephrine and 3 H-acid metabolites in all of the peripheral and central regions with the exception of the hypothalamus. The rate of uptake of 3 H-epinephrine was extremely high in hypophysectomized pregnant rats and very low in progesterone-treated females. Results suggest that steroid and peptide hormones play an important role in the control of monoaminergic function during late pregnancy.

Central and peripheral catecholamines and phenylethanolamine-N-methyl-transferase activity during the oestrus cycle.

Natural variations in monoamine levels in the adrenal gland, whole brain, hypothalamus and plasma during the oestrus cycle were determined in Sherman rats. Noradrenaline content of adrenal gland was at its highest level during met-oestrus phase while adrenaline was at its lowest level. During pro-oestrus adrenaline in the adrenal gland was at the maximum value. Plasma adrenaline did not change significantly during the oestrus cycle. However plasma noradrenaline was significantly higher during metoestrus compared to the value for di-oestrus and pro-oestrus. In the hypothalamus noradrenaline level was at its highest value during di-oestrus and at its lowest during met-oestrus, while brain noradrenaline reached its maximum value during pro-oestrus. The sum of plasma adrenaline and noradrenaline showed maximum level during met-oestrus phase but at the same time total adrenal adrenaline plus noradrenaline was lowered. The variations in adrenaline and noradrenaline in the adrenal gland did not correspond to the changes in the activity of enzyme, phenylethanolamine-N-methyltransferase (PNMT). The activity of PNMT reached its maximum value during met-oestrus phase of the oestrus cycle. The observed variations in adrenal, brain, hypothalamus and plasma catecholamines can be attributed to the modification in endocrine activity which takes place during the oestrus cycle.

Effects of thyroidectomy and L-thyroxine on adrenaline and noradrenaline concentrations in the adrenal glands and plasma of rats during the pro-oestrous phase of the oestrous cycle and pregnancy.

1The influence of thyroidectomy upon the adrenaline and noradrenaline content of adrenal glands and plasma in mature female rats in pro‐oestrus and in pregnant rats was studied.

Maintenance of central and peripheral monoamine oxidase activity in developing rats subjected to disturbed alimentary rhythms and undernutrition.

Monoamine oxidase (MAO) activity was studied in whole brain, hypothalamus, adrenals and liver of developing rats subjected to disturbed feeding patterns or undernutrition for 3 weeks. The rats were divided into six groups: (1) normally fed controls; (2) rats starved for 24 h, fed for the following 8 h and killed after the last starvation period (PAS); (3) same treatment as in (2) but killed after the last feeding period (PAF); (4) rats starved for 16 h, fed for the following 8 h at a constant schedule, and killed after the last starvation period (PS); (5) same treatment as in (4) but killed after the last feeding period (PF), and (6) undernourished (U). Alteration of the feeding time resulted in significant decreases of MAO activity in the brain and the adrenal gland whereas the hypothalamus and the liver showed a slight increase in activity in the PAS group. In PS rats, MAO activity increased in the brain, adrenals and hypothalamus; in PF rats, the effects of the treatment were inverse. Both in the PS and PF rats, hepatic MAO activity was strongly decreased when assayed with kynuramine. In U rats, hepatic MAO activity was highly increased when assayed with kynuramine but the other tissues responded differently. The adrenaline and noradrenaline stocks of the adrenal gland were markedly increased in all the treated groups; the maximum increase in noradrenaline was observed in the PS rats. The results suggest that any disturbance in the feeding pattern affects the MAO activity in the central and peripheral regions of the young rat during postnatal development. The developing rat seems to get accustomed to new alimentary rhythms, and normal monoaminergic function is rapidly restored when the rat is given a compensatory diet. Increased adrenal catecholamines after a disturbance in the feeding patterns seem to be a response to stress.

Influence of progressive starvation upon brain and adrenal monoaminergic activity in developing rats of two different ages.

Experiments show the influence of progressive starvation upon the synthetic and metabolic activity of monoaminergic function in the brain and the adrenal gland of young rats of two different ages. Brain and adrenal monoamine oxidase (MAO) showed a tendency to decline with the prolongation of the starvation interval. After 60 h of starvation, MAO activity was irreversibly decreased, even with 24 h of feeding, in the two age groups. Cerebral catechol-O-methyltransferase (COMT) activity was very slightly affected in response to the starvation in the older group, but the younger group showed an increased level of enzyme activity, and refeeding after 60 h of starvation of the young rats produced further increases. 60 h of starvation produced an increase in COMT activity of the adrenal gland of the older rats whereas the younger group did not show any marked change. Adrenal phenylethanolamine-N-methyltransferase (PNMT) declined after 24 and 48 h of starvation in the older rats, but the younger rats showed progressive increases after similar intervals of starvation. After 60 h of starvation, PNMT in the adrenal gland of the old rats increased significantly when compared to the control value, but the younger rats did not show any important change. Adrenal stores of adrenaline rose progressively up to 60 h of starvation in the old rats whereas the younger group responded in a contrary manner. Adrenal noradrenaline followed a similar pattern of evolution in both groups up to 60 h of starvation (when the results are expressed per milligram of adrenal protein), and refeeding had very little influence on the effects of starvation. The effects of starvation upon adrenal and cerebral MAO activity were verified with two different substrates. The results provide evidence that the metabolism of monoamines by oxidative deamination can be markedly affected by starvation, and this can be irreversible even after 24 h of feeding of starved rats. COMT activity augments when MAO activity declines.

Variations in mitochondrial monoamine oxidase during progressive starvation in the brain of developing rats.

Effects of progressive starvation of 12, 24, 48 and 60 h upon brain mitochondrial monoamine oxidase activity were studied. The enzyme activity was determined by three different substrates: 14C-labeled tryptamine, dopamine and kynuramine. With dopamine as substrate, the enzyme activity showed decline during 24 and 48 h of starvation. Monoamine oxidase when determined by tryptamine as the substrate, showed a decrease after 60 h of starvation. The use of kynuramine as substrate also produced a decrease in enzyme activity after 48 and 60 h of starvation. Refeeding the 60-h-starved rats for the following 24 h resulted in further decrease of monoamine oxidase activity of brain mitochondria from the 60 h starved values. The results suggest that oxidative deamination of biogenic amines is greatly inhibited during progressive starvation and remains low even after feeding the 60 h starved rats for 24 h.