Neurochemical correlates of behavior. Content of tryptophan, 5-hydroxytryptophan, serotonin, 5-hydroxyindoleacetic acid, tyrosine, dopamine and norepinephrine in a nerve ending fraction isolated from three brain areas of the pigeon during the period of behavioral depression following an injection of tryptophan

The Impact of Essential Amino Acids on the Gut Microbiota of Broiler Chickens

The research involving the beneficial aspects of amino acids being added to poultry feed pertaining to performance, growth, feed intake, and feed conversion ratio is extensive. Yet currently the effects of amino acids on the gut microbiota aren't fully understood nor have there been many studies executed in poultry to explain the relationship between amino acids and the gut microbiota. The overall outcome of health has been linked to bird gut health due to the functionality of gastrointestinal tract (GIT) for digestion/absorption of nutrients as well as immune response. These essential functions of the GI are greatly driven by the resident microbiota which produce metabolites such as butyrate, propionate, and acetate, providing the microbiota a suitable and thrive driven environment. Feed, age, the use of feed additives and pathogenic infections are the main factors that have an effect on the microbial community within the GIT. Changes in these factors may have potential effects on the gut microbiota in the chicken intestine which in turn may have an influence on health essentially affecting growth, feed intake, and feed conversion ratio. This review will highlight limited research studies that investigated the possible role of amino acids in the gut microbiota composition of poultry.

Dietary tryptophan effects on growth and stress responses of male broiler chicks

1. Three experiments were conducted to determine growth of broiler chicks fed on test diets formulated to be deficient or adequate in tryptophan (Trp) using gelatin by-product as a means of generating a Trp deficiency. Growth response estimates of broiler chicks to graduations of Trp were determined by dose-response criteria and regression analyses. Experiments were conducted using broiler chicks from 1 to 20 d of age. 2. Broiler chicks fed Trp-deficient diets had poor body weight gain, feed intake and feed conversion. Recommended total Trp needs were 2.0, 2.1 and 2.2 g/kg for feed intake, body weight gain and feed conversion, respectively. 3. Blood plasma Trp exhibited a sigmoidal trend while blood plasma glucose increased in a linear manner to supplemental Trp. Physiological stress variables measured were unaffected by dietary Trp.

Serotonergic involvement in the backward tumbling response of the parlor tumbler pigeon

The parlor tumbler is a breed of domestic pigeon which displays a hereditary movement disorder resulting in backward somersaulting upon attempting to fly. A neurochemical abnormality has been suggested to underlie this behavior. The effect on tumbling of several drugs with serotonergic actions was studied. Increasing available serotonin with 5-hydroxytryptamine (50 mg/kg) plus fluoxetine (10 mg/kg) as well as using amitriptyline (10-20 mg/kg) significantly suppressed tumbling without sedation. This suggests that serotonin mechanisms may be involved in the tumbling response.

Comparative study of monoamine levels in discrete brain areas of five rodent species

1. Dopamine, norepinephrine, serotonin and 5-hydroxyindol-acetic acid levels were studied in discrete brain areas of four wild rodent species and compared with those of laboratory mouse. 2. Monoamine levels showed significant differences in all the species studied. 3. Although it is not possible to exclude the changes induced by the captivity's stress, the results suggest that the natural hypoxic environment (high altitude) and/or the natural diet play an important role on the activity of the monoaminergic neurons. 4. Species which showed a better behavioral pattern of adaptation also showed significant differences in brain monoamine levels.

Effect of prenatal phenytoin administration on brain tryptophan metabolism of rat offspring during the preweaning period

Serum 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) concentrations in control rat offspring increased progressively during the preweaning period reaching adult values by day 21. It has been shown the prenatal phenytoin administration (100 mg kg-1 orally, days 7-19 of pregnancy) increased serum tryptophan and brain tryptophan, 5-HT and 5-HIAA of rat offspring at 3 days of age but not at 4, 15 or 21 days of age. The effect of prenatal phenytoin administration on the offspring at 3 days of age was not observed when these pups were cross-fostered to control mothers at 2 days of age suggesting that the alteration in rain tryptophan metabolism during the development of tryptaminergic neurons in rat offspring, as a result of prenatal phenytoin administration is mediated through changes in lactation or nursing ability of the mothers. It is important that such non-specific factors are controlled when studying the effect of prenatally administered drugs on neonatal brain transmitter concentrations.

The effect of L-tryptophan on motor activity and its prevention by an extracerebral decarboxylase inhibitor and by 5-HT receptor blockers

L-Tryptophan at moderately low dosage (20 mg/kg) reduced the activity of rats taken during a dark period (red light) and put into an open field illuminated by bright white light. Activity was not altered when the field was illuminated by red light. Tryptophan did not cause significant hypoactivity in rats pretreated with the 5-hydroxytryptamine (5-HT) receptor antagonists methysergide, cyproheptadine and metergoline. However, tryptophan did not alter brain 5-HT concentration and only increased 5-hydroxyindoleacetic acid (5-HIAA) slightly in rats killed shortly after behavioural observation. A further indication that the behavioural effect of tryptophan was not due to increased brain 5-HT was its prevention by R04-4602 at a dose sufficient to block peripheral but not central L-aromatic amino acid decarboxylase. The results suggest that the above behavioural effect of L-tryptophan is peripherally mediated. A number of potential mechanisms are discussed.