Variation In Serotonin Content Research Articles

Seasonal and Geographic Variation in Serotonin Content in Sea Buckthorn

Plants growing in unfavorable environments, such as sea buckthorn, can have a high serotonin content. The potential of using different parts of sea buckthorn (Hippophae rhamnoides L.) as a natural source of serotonin was investigated. The feasibility of extracting serotonin hormone from the non-fruit parts of sea buckthorn is demonstrated. One- and two-year-old woody shoots were the best material for obtaining serotonin-containing raw product. Serotonin content in shoots of different sea buckthorn varieties growing in different regions and its dynamics during the vegetation period were determined by high-performance liquid chromatography. Serotonin is a water-soluble substance prone to microbial degradation, so proper preparation of raw materials plays a very important role in preserving serotonin in plant samples. A method for serotonin extraction using preliminary mechanochemical treatment is presented: it consists in pre-grinding, followed by mechanical treatment of raw materials with 5% adipic acid in a semi-industrial centrifugal mill. The highest degree of serotonin extraction was achieved when using air circulation at a drying temperature of 60-80°C; serotonin concentration decreased when temperature was further increased. Serotonin content depended on the place and time of harvesting, the method used for drying the branches, and the characteristics of the plant variety. The minimum serotonin concentration (29mg/g dry basis) was observed during summer; the maximum concentration was observed during winter; the annual changes in concentration can be as significant as 10-fold. The possibility of industrial cultivation and harvesting of different sea buckthorn varieties was also considered.

Effect of Emotional Stress on Biogenic Amine Content in the Sensorimotor Cortex of Rats with Experimental Intracerebral Hemorrhage

Experiments on the model of an aggressive-conflict situation were designed to study the effect of emotional stress on biogenic amine content in the sensorimotor cortex of the right cerebral hemisphere in behaviorally active and passive rats with experimental hemorrhage in the left caudate nucleus of the brain. Prior exposure to stress in active and, particularly, in passive animals was shown to modify the type of neurochemical reactions in brain tissue during modeling of intracerebral hemorrhage. As differentiated from rats with experimental hemorrhagic stroke, passive specimens of this series were characterized by a slight increase in norepinephrine content and significant elevation of dopamine level in the sensorimotor cortex on day 3 of the study. An increase in dopamine content in brain tissue of stressed active rats was observed on days 1 and 3, which corresponded to the immediate and acute stages of the post-stroke period. Variations in serotonin content in the sensorimotor cortex of animals with post-stress intracerebral hemorrhage had the same dynamics, but were less pronounced than in non-stressed rats. Our results illustrate the specific involvement of brain biogenic amines in animals with various behavioral characteristics in the adaptive and compensatory processes, which occur during various stages of experimental intracerebral hemorrhage after stress exposure.

Effect of Nonselective β-Adrenoblockers on the State of Sympathoadrenal System and Ratio of Neuroactive Amino Acids in Rat Medulla Oblongata

Experiments on rats showed that injection of propranolol into the medulla oblongata increased the contents of epinephrine, norepinephrine, dopamine, and L-DOPA by 3.76, 1.4, 2.0, and 1.7 times, respectively. These propranolol-induced changes in the levels and ratio of neurotransmitters were not accompanied by variations in serotonin content. Propranolol had no significant effects on the content of excitatory amino acids, except marked increase in aspartate content. The level of inhibitory amino acids increased mainly due to an increase in GABA content. The balance between excitatory and inhibitory amino acids was shifted towards inhibitory compounds.

Tryptophan metabolism via serotonin in rats with hexachlorobenzene experimental porphyria

One of the three pathways for the metabolisation of dietary tryptophan is the formation of serotonin. Tryptophan hydroxylase catalyses the formation of 5-hydroxytryptophan, the first and regulatory step of this biosynthesis. The aim of the present work is to study alterations in this tryptophan metabolism in rats with experimental Porphyria Cutanea Tarda induced by hexachlorobenzene. With this purpose, the content of tryptophan and its metabolites related to the serotonin pathway are determined by HPLC techniques, in tissues (brain, liver and gut) and in fluids (blood, plasma and urine) of controls and hexachlorobenzene-porphyric rats. In these experimental-porphyric animals, we determine a significant increase in the excretion of 5-hydroxyindole acetic acid in urine and a decrease in the content of serotonin in small gut, respect to controls. Significant increases in contents of serotonin in 24-hr urine and tryptophan in liver are also found. No other significant variations for the different metabolites are detected in any of the tissues and fluids studied. Brain and liver activities of the rate-limiting enzyme tryptophan hydroxylase can only be measured in porphyric rats. Our results agree with an increased turnover of gastrointestinal serotonin derived from dietary tryptophan and its excretion as urinary 5-hydroxyindole acetic acid, which is formed in liver. An increased serotonin pathway in porphyric livers is confirmed by the measured increase in the activity of hepatic tryptophan hydroxylase. The absence of neurological symptoms in patients with Porphyria Cutanea Tarda could be related to the absence of a statistically significant variation in serotonin content shown in brain.

Serotonin N-acetyltransferase activity as a target for temperature in the regulation of melatonin production by frog retina

The adaptive mechanisms of serotonin N-acetyltransferase (NAT) activity in the regulation of melatonin synthesis in frog retina in the face of chronic and acute temperature changes have been investigated. We performed thermal acclimation experiments to test different environmental temperatures at two seasons of the year (summer and winter), followed by the set-up of an eyecup culture system to investigate the acute effects of temperature on NAT activity and melatonin production daily rhythms. Low temperature induced a significant increase in NAT activity, independent of both the time of the photocycle (midday or midnight) and the season of the year (winter or summer). Acute cold-induced stimulation of NAT activity may be associated with lower decreases in the enzyme synthesis rate, rather than decreases in the degradation rate. In contrast, acclimation to warm temperature (25 degrees C) stimulated ocular melatonin production. Nocturnal melatonin production in eyecups cultured at 25 degrees C was significantly higher than in eyecups cultured at 5 degrees C. We suggest that this discrepancy in thermal regulation of melatonin synthesis can be justified by a seasonal variation in serotonin content within the photoreceptor cells, which determines the thermal response of melatonin production through changes in NAT kinetics.