Mycobacterium avium subsp. paratuberculosis in Wild Boar (Sus scrofa) in Portugal.

Paratuberculosis, or Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic granulomatous enteritis affecting both domestic and wild ruminants. The agent was also found in wild mammals such as wild boar (Sus scrofa); however, the role of wild mammals in the epidemiology of MAP is unclear. During the research period, 941 free-ranging wild boar (S. scrofa) legally hunted in two locations in the central-eastern region of Portugal were examined. Ninety-seven wild boars exhibited one or more gross lesions and were tested for the presence of Mycobacterium avium subsp. paratuberculosis using acid-fast staining, mycobacterial culture, polymerase chain reaction (PCR), and histopathological examination. Forty-five animals (46.4%, 95% CI: 36.5-56.3%) were identified as infected, as indicated by positive results in culture and/or PCR. The findings revealed that the most significant risk factor was being a juvenile compared to yearlings and adults (OR = 10.2, 95% CI: 2.2-48.0). Based on our results, 37.9% (n = 11) of the infected animals were considered suitable for human consumption. Our findings offer novel insights into mycobacterial infections in wild boar populations in Portugal and suggest that wild boar could be a source of human infection if zoonotic potential is considered.

Hunting for Answers: Assessing Brucella spp. Seroprevalence and Risks in Red Deer and Wild Boar in Central Portugal.

Between 2016 and 2023, a cross-sectional study was conducted in the central region of Portugal in order to better understand the epidemiology and public health risks resulting from the handling and consumption of game animals infected with Brucella spp. The seroprevalence and risk factors for Brucella spp. seropositivity were evaluated. Antibodies against Brucella spp. were determined using a commercial enzyme-linked immunosorbent assay (ELISA) according to the manufacturer's instructions. Results showed that in the 650 serum samples collected from red deer (n = 298) and wild boars (n = 352) in Portugal, 21.7% (n = 141; 95% CI: 18.6-25.1%) tested positive. Wild boar had a significantly higher prevalence (35.5%; 95% CI: 30.5-40.8%) than red deer (5.4%, 95% CI: 3.1-8.6%; p ≤ 0.001). Risk factors for seropositivity were investigated using multivariable logistic regression models. The odds of being seropositive was 8.39 (95% CI: 4.75-14.84; p ≤ 0.001) times higher in wild boar than in red deer. Correlations between sex, age, body condition, and seropositivity could not be observed. The higher seroprevalence in wild boar suggests that this species may primarily contribute to the Brucella spp. ecology in central Portugal.

Design and Development of a Web-Based Prospective Nationwide Registry for Ocular Inflammatory Diseases: UVEITE.PT - The Portuguese Ocular Inflammation Registry.

Uveitis is a heterogeneous collection of infrequent diseases, which poses significant challenges to cost-effective research in the field. Medical registries are being increasingly recognized as crucial tools to provide high-quality data, thus enabling prospective clinical research. This paper describes the design and technical structure development of an innovative countrywide electronic medical record for uveitis, Uveite.pt, and gives an overview of the cohort registered since its foundation, March 2020.Uveite.pt is an electronic medical record platform developed by the Portuguese Ocular Inflammation Group (POIG), a scientific committee of the Portuguese Ophthalmology Society. This is a nationwide customized web-based platform for uveitis patients useful for both clinical practice and real-world-based research, working as a central repository and reporting tool for uveitis. This paper describes the technical principles, the design and the development of a web-based interoperable registry for uveitis in Portugal and provides an overview of more than 400 patients registered in the first 18 months since inception.In infrequent diseases, the existence of registries enables to gather evidence and increase research possibilities to clinicians. The adoption of this platform enables standardization and improvement of clinical practice in uveitis. It is useful to apprehend the repercussion of medical and surgical treatments in uveitis and scleritis, supporting clinicians in the strict monitoring of drug adverse reactions and surgical outcomes.

Prevalence and Risk Factors for Hepatitis E Virus in Wild Boar and Red Deer in Portugal.

Hepatitis E virus (HEV) is a zoonotic foodborne virus with an annual infection prevalence of 20 million human cases, which seriously affects public health and economic development in both developed and developing countries. To better understand the epidemiology of HEV in Central Portugal, a cross-sectional study was conducted from 2016 to 2023 with sera samples from wild ungulates. The seroprevalence and risk factors for HEV seropositivity were evaluated in the present study. Specifically, antibodies against HEV were determined by a commercial enzyme-linked immune-sorbent assay (ELISA). Our results show that in the 650 sera samples collected from 298 wild red deer and 352 wild boars in Portugal, 9.1% red deer and 1.7% wild boar were positive for antibodies to HEV. Regarding age, the seropositivity in juvenile wild ungulates was 1.3%, whereas it was 7.2% in adults. Logistic regression models investigated risk factors for seropositivity. The odds of being seropositive was 3.6 times higher in adults than in juveniles, and the risk was 4.2 times higher in red deer than in wild boar. Both wild ungulate species were exposed to HEV. The higher seroprevalence in red deer suggests that this species may make a major contribution to the ecology of HEV in Central Portugal. Further research is needed to understand how wildlife affects the epidemiology of HEV infections in Portugal.

First morphological and molecular isolation of Talaromyces marneffei in beech marten (Martes foina) in Portugal.

Talaromyces marneffei is a zoonotic fungus that mostly infects immunocompromised individuals. For the first time, this fungus was isolated in an adult beech marten (Martes foina) hit by a car, found dead in Penamacor, Portugal. During the necropsy, different samples (skin, fur, lymph nodes, lung, spleen, kidneys, and brain) were collected and processed for microbiology (including mycology) and molecular biology. T. marneffei was identified through its mycological characteristics and confirmed by PCR in hair samples. No other lesions or alterations were reported, except a concomitant presence of M. avium subsp. paratuberculosis in lung, kidney and brain samples. To the authors' knowledge, this is the first description of this fungus beech marten, as well as the first case of co-infection with M. avium subsp. paratuberculosis in wildlife fauna. These results suggest a sylvatic life-cycle of T. marneffei, involving beech martens, in Portugal.

Estimating sequence diversity of prion protein gene (PRNP) in Portuguese populations of two cervid species: red deer and fallow deer.

Among the transmissible spongiform encephalopathies (TSEs), chronic wasting disease (CWD) in cervids is now a rising concern in wildlife within Europe, after the detection of the first case in Norway in 2016, in a wild reindeer and until June 2022 a total of 34 cases were described in Norway, Sweden and Finland. The definite diagnosis is post-mortem, performed in target areas of the brain and lymph nodes. Samples are first screened using a rapid test and, if positive, confirmed by immunohistochemistry and Western immunoblotting. The study of the genetics of the prion protein gene, PRNP, has been proved to be a valuable tool for determining the relative susceptibility to TSEs. In the present study, the exon 3 of PRNP gene of 143 samples from red deer (Cervus elaphus) and fallow deer (Dama dama) of Portugal was analysed. Three single nucleotide polymorphisms (SNPs) were found in red deer - codon A136A, codon T98A, codon Q226E - and no sequence variation was detected in fallow deer. The low genetic diversity found in our samples is compatible with previous studies in Europe. The comparison with results from North America suggests that the free-ranging deer from our study may present susceptibility to CWD, although lack of experimental data and the necessity of continuous survey are necessary to evaluate these populations.

Talaromyces marneffei isolated from nasal swabs in Portugal.

Mycobiota are essential to the health of any living being, creating a balanced and complex interaction between bacteria, the immune system, and the tissue cells of the host. Talaromyces marneffei (also known as Penicillium marneffei) is a dimorphic fungus, endemic in South Asia, which often causes a life-threatening systemic fungal infection (called penicilliosis), particularly in immunocompromised hosts. Nasal swabs from 73 healthy volunteers were analysed to characterize their mycobiota, through its cultural characteristics, morphology, and molecular methods (PCR). All volunteers were also asked to answer to an anonymous questionnaire. Three women were positive (and asymptomatic) for T. marneffei. One of them was reported to have lupus. This study contributes to improving our knowledge about human normal mycobiota, identifying mycotic agents that may cause complicated systemic infections (as T. marneffei), especially in immunosuppressed patients, as well as other possible risk factors of exposure or prognosis.

• Talaromyces marneffei is a zoonotic fungus that may be responsible for life-threatening systemic infections in immune-comprised patients. • Talaromyces marneffei was identified in nasal swabs from asymptomatic volunteers. • This suggests that this fungus may be part of the nasal normal mycobiota of some humans.

Seropositivity for Coxiella burnetii in Wild Boar (Sus scrofa) and Red Deer (Cervus elaphus) in Portugal.

Q fever is caused by the pathogen Coxiella burnetii and is a zoonosis that naturally infects goats, sheep, and cats, but can also infect humans, birds, reptiles, or arthropods. A survey was conducted for the detection of antibodies against C. burnetii in a sample of 617 free-ranging wild ruminants, 358 wild boar (Sus scrofa) and 259 red deer (Cervus elaphus), in east-central Portugal during the 2016-2022 hunting seasons. Only adult animals were sampled in this study. Antibodies specific to C. burnetii were detected using a commercial enzyme-linked immunosorbent assay (ELISA; IDVet®, Montpellier, France) according to the manufacturer's instructions. The seroprevalence of C. burnetii infection was 1.5% (n = 9; 95% confidence interval [CI]: 0.7-2.8%). Antibodies against C. burnetii were detected in 4/358 wild boar (1.1%; 95% CI: CI: 0.3-2.8%) and 5/259 red deer (1.9%; 0.6-4.5%). Results of the present study indicate that antibodies against C. burnetii were present in wild boar and red deer in Portugal. These findings can help local health authorities to focus on the problem of C. burnetii in wildlife and facilitate the application of a One Health approach to its prevention and control.

Outcome of Uveitis in Juvenile Idiopathic Arthritis and Spondyloarthritis Patients - A 5-Year Follow-Up Study.

OBJECTIVE: Uveitis is a frequent complication of juvenile idiopathic arthritis (JIA) and spondyloarthritis (SpA). The aim of this study is to evaluate the prevalence and risk factors for complications associated with uveitis in patients with JIA and SpA. METHODS: A longitudinal, monocentric cohort study that included patients diagnosed with JIA and SpA who developed uveitis. Demographic, laboratory, and clinical data were collected including complications of uveitis, HLA-B27, antinuclear antibodies, erythrocyte sedimentation rate, C-reactive protein, visual acuity and DMARD treatment. Comparison between groups (complicated versus uncomplicated uveitis) was evaluated using chi-square, t test and Mann-Whitney U test. Logistic regression was performed to determine predictors of complications. RESULTS: A total of 270 patients were evaluated, of which 37 patients (13.7%) had uveitis and were included in this study. Twenty patients were female (54.1%), aged 11.9±8.7 years at diagnosis of SpA/JIA and 15.3±9.9 years at diagnosis of uveitis. Twenty-seven patients (73.0%) had a diagnosis of JIA (23 with oligoarticular disease) and in 12 patients (32.4%) uveitis was the first manifestation. Fifteen (40.5%) patients exhibited complications during follow-up period. Eleven patients (29.7%) underwent ophthalmologic surgery. Complications were significantly higher in patients with JIA (51.9% vs 10.0% in SpA, p=0.03), as was the need for surgery (40.7% vs 0%, p=0.02). Complications in JIA were significantly more frequent in patients who had uveitis as the initial presentation (50.0% vs 7.7%, p=0.03); no significant differences were found between the groups in the other variables studied. Univariate logistic regression analysis showed that uveitis as the first manifestation of JIA (OR 12.0, confidence interval 95% 1.21-118.89, p=0.03) is a significant predictor of complications. CONCLUSION: We found higher rates of complications and need for ophthalmologic surgery in patients with JIA-associated uveitis. The initial presentation of JIA as uveitis is significantly associated with the occurrence of uveitis complications, so it is essential that there is a collaboration between ophthalmologist and rheumatologist in the diagnosis and treatment of these patients.

Clinical Features and Outcomes of Tubulointerstitial Nephritis and Uveitis Syndrome in Spain and Portugal: The IBERTINU Project.

PURPOSE: To assess the clinical features, management and prognosis of patients diagnosed with tubulointerstitial nephritis and uveitis (TINU) syndrome in Spain and Portugal. METHODS: Retrospective multicenter study, which included all patients diagnosed with TINU syndrome managed in 15 uveitis referral centers from Spain and Portugal. RESULTS: Forty-eight subjects with a mean age at diagnosis of 25.0 [14.8; 49.5] years were included. Both eyes were affected in 43 patients (89.6%). The visual outcome was favorable, but immunosuppressive systemic therapy (IST) was needed in 26 (54.16%) due to relapses. Renal function normalized in 35 patients (72.9%). HLA-DQB1*05 was the most common genetic typing (57.1%). The mean follow-up time was 22.5 [11.0; 48.0] months. CONCLUSIONS: Both visual and renal outcomes were favorable, although IST was frequently used. TINU is under- diagnosed, so further prospective studies would provide more knowledge about its recognition and management. EXPERT OPINION: TINU Syndrome is underdiagnosed because ocular and renal disease are asynchronous. Outcomes are favorable so it has to be highly suspected in cases of bilateral anterior uveitis. According to literature and our experience, systemic immunosuppressive therapy is often required because of ocular relapses.This study adds to the previous knowledge that HLA-DQB1*05 could be an important HLA type amongst the TINU Syndrome Iberian population. HLA typing should be assessed in these patients in order to describe its phenotype-genotype relationship better. A considerable number of patients in our series were diagnosed in their sixties, so TINU Syndrome should also be suspected in elderly patients.

Nonmetastatic Castration-Resistant Prostate Cancer: Current Challenges and Trends.

Prostate carcinoma is a highly prevalent biologically and clinically diverse disease, generally associated with a consistent elevation of prostate-specific antigen levels. Castration-resistant prostate cancer represents a heterogeneous clinical setting that ranges from patients with an asymptomatic prostate-specific antigen elevation after hormone blockade failure and good performance status to patients with significant debilitating symptoms and rapidly progressive disease, leading to death. Nonmetastatic castration-resistant prostate cancer is a transient disease stage defined over specific criteria established within a sensitive time period. The majority of the patients with nonmetastatic castration-resistant prostate cancer will eventually develop metastatic lesions, associated with prostate cancer-specific morbidity and mortality. However, progression to metastatic disease is a heterogeneous process still not fully understood, with studies suggesting that younger age, high Gleason score (> 7), high prostate-specific antigen levels, reduced prostate-specific antigen doubling time (< 6 months), and a rapid alkaline phosphatase rise as potentially associated factors. Although the nonmetastatic castration-resistant prostate cancer treatment landscape has substantially evolved in recent years, the disease heterogeneity makes treatment decisions for this population challenging in the effort to achieve a balance between the risk of disease progression and the toxicity of new treatments in patients who often have associated comorbidities, yet are generally asymptomatic. The present article addresses the current main challenges in nonmetastatic castration-resistant prostate cancer management, including in diagnosis, owing to the development of new imaging modalities with a direct impact in disease detection, prognostic classification, as a result of the traditionally oversimplified definition of disease aggressiveness (mainly based on prostate-specific antigen doubling time), and patient selection for the most adequate treatment.

The 2021 Portuguese Society of Ophthalmology joint guidelines with Paediatric Rheumatology on the screening, monitoring and medical treatment of juvenile idiopathic arthritis-associated uveitis.

AIM: To develop the first Ophthalmology joint guidelines with Paediatric Rheumatology with recommendations on the screening, monitoring and medical treatment of juvenile idiopathic arthritis-associated uveitis (JIA-U), endorsed by the Portuguese Society of Ophthalmology (SPO). METHODS: A systematic literature review was conducted to include publications up to July 14th 2020, with no language restrictions, in order to include all the international position papers/guidelines concerning the medical management of JIA-U and randomised clinical trials assessing the efficacy and safety of medical treatment in this field. We searched through MEDLINE (PubMed), Scopus, Web of Science and Cochrane Library. The Delphi modified technique to generate consensus was used. Preliminary evidence statements were subject to an anonymous agreement assessment and discussion process using an online survey, followed by further discussion and update at a national meeting. A draft of the manuscript with all recommendations was then circulated among all participants and suggestions were incorporated. The final version was again circulated before publication. RESULTS: Twenty-six recommendations were developed focusing on the following topics: general management (3), screening and follow-up of uveitis (4), treatment (17) and health education in JIA-U among patients and families (2). CONCLUSION: These guidelines were designed to support the shared medical management of patients with JIA-U and emphasize the need for a multidisciplinary approach between Ophthalmology and Paediatric Rheumatology regarding the comprehensive care of JIA-U. We acknowledge that updating these recommendations will be warranted in the future, as more evidence becomes available. KEY-WORDS: juvenile idiopathic arthritis, uveitis, biological treatment, conventional immunosuppressive treatment, multidisciplinary management, guidelines, consensus, review, Delphi Technique.

Efficacy and Safety of Corticosteroid Implants in Non-infectious Uveitis: A Systematic Review with Network Meta-analysis.

BACKGROUND/AIMS: To compare different existent implants for noninfectious uveitis. METHODS: We performed a systematic review of randomized clinical trials (RCTs), searching in five electronic databases and screening reference lists of included studies and relevant reviews. We performed network meta-analysis to compare 0.18 mg fluocinolone acetonide implants, 0.70 mg and 0.35 mg dexamethasone implants, and sham procedures. RESULTS: Eight RCTs were included in this systematic review, of which three articles from two studies (n = 358 patients) were included in network meta-analysis. The 0.70 mg dexamethasone implant (at 1.5 months) was associated with better results than the 0.18 mg fluocinolone acetonide implant (at 1 month) at improving vitreous haze grading (RR = 2.96; 95%CI = 1.23-7.07), and with less frequently development of cataracts at 12 (RR = 0.36; 95%CI = 0.17; 0.79) and 36 months (RR = 0.37; 95%CI = 0.20; 0.71). CONCLUSIONS: In the short term, the 0.70 mg dexamethasone implant is superior at improving vitreous haze, and shows lower risk of cataracts. However, additional RCTs with standardized outcomes are needed.

Efficacy and safety of intravitreal and periocular injection of corticosteroids in noninfectious uveitis: a systematic review.

Uveitis is among the leading causes of visual loss in the working age population. In noninfectious uveitis, corticosteroids are the first line therapy. We sought to review systematically the evidence regarding the regional corticosteroid delivery modalities in the treatment of noninfectious uveitis. A 5-database search (Pubmed, ISI Web of Science, Cochrane, ClinicalTrials.gov, and Scopus) was performed from inception to February, 2021. Nineteen studies with a total of 1,935 eyes of 1,753 patients were selected from 8,922 abstracts retrieved by the initial search. The most frequently compared regimens were intravitreal triamcinolone acetonide injection and orbital floor triamcinolone acetonide injection (2 studies), intravitreal triamcinolone acetonide injection and posterior sub-Tenon triamcinolone acetonide injection (2 studies), and posterior sub-Tenon triamcinolone acetonide injection with the intravitreal dexamethasone implant (2 studies). Our results show that the intravitreal injection of corticosteroids is more effective, but is associated with more adverse events, than periocular injection. Some evidence supports the use of subconjunctival triamcinolone acetonide over intravitreal/periocular triamcinolone acetonide. Moreover, the overall results of 0.59 mg dosage of the intravitreal fluocinolone acetonide implant were superior to those from the 2.1 mg dose. The evidence, however, is not robust, and further studies with standardized outcomes are warranted.

A painful red eye in an intravenous drug abuser: When not everything is what it seems.

INTRODUCTION: Endogenous endophthalmitis is a rare but devastating ocular infection, resulting from microbial seeding of the eye during bacteremia or fungemia. Among other sources of septicemia, intravenous drug abuse is a significant risk factor, and endogenous endophthalmitis should always be thought of in any patient with a history of injectable drug use, presenting with a painful vision loss and a red inflamed eye. CASE DESCRIPTION: We report the case of a 47-year-old male, with a history of injectable drug consumption, who presented to our emergency department complaining of a painful red eye and recent deterioration of visual acuity. After the first clinical hypothesis of endogenous endophthalmitis being considered, the final diagnosis of Human Leukocyte Antigen (HLA) B27-associated acute anterior uveitis was established. CONCLUSION: Ocular inflammation is one of the most challenging fields in all ophthalmology. Several inflammatory disorders, ranging from a wide variety of infectious and non-infectious conditions, can present themselves with the same clinical signs and symptoms, making their diagnosis extremely defiant.

Scrapie at Abattoir: Monitoring, Control, and Differential Diagnosis of Wasting Conditions during Meat Inspection.

Wasting disease in small ruminants is frequently detected at slaughterhouses. The wasting disorder is manifested by the deterioration of the nutritional and physiological state of the animal indicated by thinness, emaciation, and cachexia. Evidence of emaciation and cachexia, alone, are pathological conditions leading to carcass condemnation during an inspection. Several diseases are associated with a wasting condition, including scrapie, pseudotuberculosis, tuberculosis, paratuberculosis, Maedi Visna, and tumor diseases. On the other hand, parasitic diseases, nutrition disorders, exposure or ingestion of toxins, metabolic conditions, inadequate nutrition due to poor teeth, or poor alimentary diet are conditions contributing to poor body condition. Classical and atypical scrapie is naturally occurring transmissible spongiform encephalopathies in small ruminants. The etiological agent for each one is prions. However, each of these scrapie types is epidemiologically, pathologically, and biochemically different. Though atypical scrapie occurs at low incidence, it is consistently prevalent in the small ruminant population. Hence, it is advisable to include differential diagnosis of this disease, from other possibilities, as a cause of wasting conditions detected during meat inspection at the abattoir. This manuscript is a review of the measures in force at the abattoir for scrapie control, focusing on the differential diagnosis of gross lesions related to wasting conditions detected in small ruminants during meat inspection.

Inflammatory Choroidal Neovascular Membranes: Clinical Profile, Treatment Effectiveness, and Visual Prognosis.

PURPOSE: To characterise a sample of patients with inflammatory choroidal neovascularization (I-CNV), including clinical profile, underlying aetiology and its course, treatments performed, associated clinical response, and visual prognosis. METHODS: Retrospective analysis of patients with a diagnosis of I-CNV followed at the Ophthalmology Department of Centro Hospitalar Universitário de São João (CHUSJ). Clinical and visual outcomes were classified according to the difference in visual acuity after treatment. RESULTS: Twenty eyes from 17 patients were analysed (11 female and 6 male patients, mean age 41.90 ± 16.457 years at CNV diagnosis). Punctate inner choroidopathy/multifocal choroiditis was the predominant inflammatory aetiology (10 patients, 58.82%). Median follow-up time was 46 months (range 10 to 188 months). Neovascularization was treated with intravitreal anti-VEGF injections (bevacizumab, aflibercept, and ranibizumab), and inflammation with anti-inflammatory/immunosuppressive therapy (oral, intravenous, and/or intravitreal corticosteroids; oral cyclosporine or methotrexate). Intravitreal anti-VEGF agents had a median number of 7.00 injections (IQR, 4.25 to 29.00). Visual acuity among 20 eyes had a mean gain of 15.10 ± 12.998 ETDRS letters after anti-VEGF treatment (p=0.000051). According to our classification, 16 had an improved outcome (80.00%), 3 had a stable outcome (15.00%), and 1 had a worsened visual outcome (5.00%). In addition, 13 eyes (65.00%) had a final VA equal to or greater than 65 letters. Recurrence was seen in 3 eyes (15.00%). Complications included cataract (6 patients) and ocular hypertension (4 patients). CONCLUSION: A combined approach with anti-VEGF agents and anti-inflammatory therapy was effective in I-CNV treatment, and an overall good visual prognosis was attainable. Intensive follow-up was fundamental in the management of both the primary inflammatory and secondary neovascular conditions.

Dietary tryptophan supplementation does not affect growth but increases brain serotonin level and modulates the expression of some liver genes in zebrafish (Danio rerio).

This study aimed at assessing the effects of the dietary tryptophan (Trp) supplementation on growth and feed utilization, brain serotonin content, and expression of selected liver genes (involved in the liver serotonin pathway, protein synthesis degradation, and antioxidant activity) in zebrafish. A growth trial was conducted with zebrafish juveniles fed five experimental isoproteic (40%DM) and isolipidic (8%DM) fishmeal-based diets containing graded levels of Trp: a Trp-non-supplemented diet (diet Trp0, with 0.22% Trp) and four Trp-supplemented diets containing 2-16 times higher Trp content (diets Trp2, Trp4, Trp8, and Trp16 with 0.40, 0.91, 2.02, and 3.34% Trp, respectively). Diets were tested in quadruplicate, with fish being fed twice a day, 6 days a week for 6 weeks to apparent visual satiation. At the end of the trial, growth performance and feed utilization were assessed, and fish from all experimental groups were sampled for whole-body composition analysis. In addition, fish fed low (Trp0), medium (Trp4), and high (Trp16) Trp diets were also sampled for analysis of brain serotonin content and liver gene expression. Tested tryptophan levels did not influence growth performance nor feed intake. However, values of energy and nitrogen retention as well as body energy content indicate a better feed utilization with diets containing around 0.9% and 2.0% DM Trp. Brain serotonin content increased with increasing dietary tryptophan levels. In addition, regarding liver genes, dietary treatment had a modulatory effect on the expression of Htr1aa and Htr2cl1 genes (encoding for serotonin receptors), TPH1a gene (encoding for tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of serotonin from tryptophan), TOR gene (involved in protein synthesis), and Keap1 gene (involved in antioxidant responses).