The Intricate Biological Proximity of Vitamin D and Brain Serotonin

Background: The purpose of this article is to extend and elaborate on our current understanding of Calcitriol and Brain Serotonin synthesis; particularly on how the two may be related. Methods: Using a 2014 study involving clinical trials to extend this hypothesis. Results: Vitamin D (Calcitriol) activated the gene that codes for Tryptophan Hydroxylase 2, which synthesizes Brain Serotonin. It also inhibits Tryptophan Hydroxylase 1, which makes serotonin in the gut. Conclusion: Vitamin D is closely related to the synthesis of Brain Serotonin. If furthered, it may be used as a treatment for the Serotonin Anomaly in Autistic Children. Keywords: 1. Biochemistry 2. Genetics 3. Neuroscience 4. Physiology

Constitutive depletion of brain serotonin differentially affects rats' social and cognitive abilities

Background: Central serotonin is an essential neuromodulator for mental disorders. It appears a promising transdiagnostic marker of distinct psychiatric disorders and a common modulator of some of their key behavioral symptoms. We aimed to identify the behavioral markers of serotonergic function in rats and compare them to human deficits. Methods: We applied a comprehensive profiling approach in adult male Tph2-/- rats constitutively lacking central serotonin. Under classical and ethological testing conditions, we tested each individual's cognitive, social and non-social abilities and characterized the group organization (i.e. social network, hierarchy). Using unsupervised machine learning, we identified the functions most dependent on central serotonin. Results: In classical procedures, Tph2-/- rats presented an unexpected normal cognitive profile. Under the complex and experimenter-free conditions of their home-cage, the same Tph2-/- rats presented drastic changes in their daily life. Brain serotonin depletion induced compulsive aggression and sexual behavior, hyperactive and hypervigilant stereotyped behavior, reduced self-care and body weight, and exacerbated corticosterone levels. Group-housed Tph2-/- rats showed strong social disorganization with disrupted social networks and hierarchical structure, which may arise from communication deficits and cognitive blunting. Conclusions: Serotonin depletion induced a profile reminiscent of the symptomatology of impulse control and anxiety disorders. Serotonin was necessary for behavioral adaptation to dynamic social environments. In classical testing conditions, our animal model challenged the concept of an essential role of serotonin in decision-making, flexibility, and impulsivity, although developmental compensations may have occurred. These contrasting findings highlight the need to generalize the evaluation of animal models' multidimensional functions within the complexity of the social living environment.

Effects of Chronic Thermal Stress on Performance, Energy Metabolism, Antioxidant Activity, Brain Serotonin, and Blood Biochemical Indices of Broiler Chickens

The aim of this paper was to investigate the effects of chronic thermal stress on the performance, energy metabolism, liver CoQ10, brain serotonin, and blood parameters of broiler chickens. In total, 100 one-day-old chicks were divided into two equal groups of five replicates. At 22 days of age and thereafter, the first group (TN) was maintained at a thermoneutral condition (23 ± 1 °C), while the second group (TS) was subjected to 8 h of thermal stress (34 °C). The heat-stressed group showed significantly lower ADFI but higher FCR than the thermoneutral group (p = 0.030 and 0.041, respectively). The TS group showed significantly higher serum cholesterol, ALT, and AST (p = 0.033, 0.024, and 0.010, respectively). Meanwhile, the TS group showed lower serum total proteins, albumin, globulin, and Na+ than the TN group (p = 0.001, 0.025, 0.032, and 0.002, respectively). Furthermore, the TS group showed significantly lower SOD and catalase in heart tissues (p = 0.005 and 0.001, respectively). The TS group showed significantly lower liver ATP than the TN group (p = 0.005). Meanwhile, chronic thermal stress significantly increased the levels of ADP and AMP in the liver tissues of broiler chickens (p = 0.004 and 0.029, respectively). The TS group showed significantly lower brain serotonin (p = 0.004) and liver CoQ10 (p = 0.001) than the TN group. It could be concluded that thermal stress disturbed the antioxidant defense system and energy metabolism and exhausted ATP levels in the liver tissues of broiler chickens. Interestingly, chronic thermal stress reduced the level of brain serotonin and the activity of CoQ10 in liver tissues.