A role for plasma aromatic amino acids in injurious pecking behavior in laying hens.

Injurious pecking, including feather pecking (FP), is one of the most prevalent causes of mortality for commercial laying hens. The underlying biological mechanisms of FP are not yet fully understood, but they could be related to alterations in the serotonin (5-HT) and/or dopamine (DA) circuits within the brain. In the past, the central synthesis of 5-HT and DA was found to be influenced by the availability of their precursors, aromatic amino acids (AAA) such as tryptophan (TRP), phenylalanine (PHE), and tyrosine (TYR), in blood plasma, which are transported across the blood-brain-barrier into the brain. Because knowledge about plasma levels of AAA in laying hens is very limited, the present study compared the AAA profiles of a large sample of laying hens from two genetic lines: one selected for low mortality (LM) due to injurious pecking (n=129 birds) and one high production line (HP) selected for high egg-production only (n=132 birds). Head, comb, and feather covering were scored at the end of the experiment. Blood samples were collected at weeks 24 and 29 of age and were analysed for AAA using high performance liquid chromatography. Neither FP nor feather damage was observed in the present study, but aggressive pecking directed at the head/neck area occurred in several groups with an onset of this aberrant behavior between weeks 22 and 29. Eight HP pens and seven LM pens were affected by severe head/comb injuries inflicted via aggressive pecking. Therefore, our exploratory data analysis focused upon the possible interplay between the variability of our outcome measures (absolute levels of AAA in plasma as well as the ratios PHE/TYR and TRP/(PHE+TYR)) and the aggressive head/comb pecking as an expression of social stress within the pens. We found significantly lower TRP availability relative to PHE and TYR (TRP/(PHE+TYR) ratio) and higher TYR concentrations at week 24 in pens with an early onset of injurious aggressive behavior at weeks 22-23. This was most pronounced in the LM line, but at week 29, TRP availability normalized in both lines. It was furthermore evident that in LM birds, higher aggressive pecking activity per pen was associated with higher TYR levels (n=78 birds, r=0.643, p<0.001) and lower TRP/(PHE+TYR) ratios at week 24 (r=-0.541, p<0.001). In the HP birds, these associations were of lower strength and were negatively correlated (TYR: n=73, r=-0.308, p=0.005; TRP/(PHE/TYR) ratio: r=0.314, p=0.004). Our findings indicate that in LM birds, lower TRP availability at week 24 may be attributable to higher stress levels in pens where injurious aggressive pecking developed early on. These findings may lay the important groundwork for the analysis of AAA plasma levels as a useful avenue of research to investigate underlying physiological mechanisms of behavioral problems in laying hens.

Sustained Increase of 25-Hydroxyvitamin D Levels in Healthy Young Women during Wintertime after Three Suberythemal UV Irradiations-The MUVY Pilot Study.

OBJECTIVES: Vitamin D (VitD) deficiency is a health problem prevalent not only in the elderly but also in young adults. The primary objective of our observational pilot study "MUVY" (Mood, UVR, Vitamin D in Young women) was to test both the short-term and long-term effects of a series of three suberythemal UV radiation (UVR) exposures on the VitD status and well-being of young healthy women during winter in a repeat measure design. METHODS: 20 healthy young women (Fitzpatrick skin types I-III, aged 21-25 years) received three full body broad band UVR exposures with an escalating erythemally weighted dose schedule during one week in winter, and completed self-report questionnaires monitoring symptoms of depression (Beck Depression Inventory, BDI) and affective state/well-being (Profile of Mood States, POMS) at baseline and three days after the last UVR exposure. 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured in serum at baseline, and at study days 8, 36 and 50. RESULTS: Mean baseline 25(OH)D level was 54.3 nmol/L (standard deviation (s.d.) = 24.1), with seven women having VitD deficient status. Relevant symptoms of depression, as indicated by low BDI total scores (0-8), were absent. After the three UVR exposures the increment of 25(OH)D was an average of 13.9 nmol/L (95% confidence interval (CI) = 9.4-18.4) and 26.2 pmol/L (95%CI = 7.2-45.1) for 1,25(OH)2D. Δ25(OH)D, and corresponding baseline levels were significantly and inversely associated (rho = -0.493, p = 0.027). Only 25(OH)D remained significantly increased above baseline for at least six weeks after the last UVR exposure. A strong inverse correlation of the POMS subscale "Vigor/Activity" and the increment in 1,25(OH)2D was found (rho = -0.739, p<0.001) at day 8. CONCLUSIONS: Three suberythemal whole body UVR exposures during one week are a simple and suitable method for improving 25(OH)D levels during winter, for at least six weeks, and especially in young women with VitD deficient status. TRIAL REGISTRATION: German Clinical Trials Register (Deutsches Register Kinischer Studien) DRKS00009274.

Cortisol, platelet serotonin content, and platelet activity in patients with major depression and type 2 diabetes: an exploratory investigation.

OBJECTIVE: Hypothalamic-pituitary-adrenal system dysfunction, serotonergic system alterations, and enhanced platelet activity may contribute to the increased cardiac risk in depression. This exploratory study examined associations between cortisol parameters, platelet serotonin (5-HT) content, and platelet activity markers in patients with newly diagnosed major depression (MD) and/or Type 2 diabetes (T2DM) compared with healthy controls. METHODS: We compared cortisol awakening response (CAR), diurnal decrease in salivary cortisol concentrations (slope), platelet 5-HT, and platelet markers (CD40, CD40 ligand [CD40L], soluble CD40L, CD62P, ß-thromboglobulin, and platelet factor-4) in 22 T2DM patients, 20 MD patients, 18 T2DM patients with MD, and 24 healthy controls. RESULTS: Platelet markers were elevated in MD (F(6,60) = 11.14, p < .001) and T2DM (F(6,60) = 13.07, p < .001). Subgroups did not differ in 5-HT or cortisol slope, whereas T2DM patients without depression had significantly lower CAR than did healthy controls (F(1,61) = 7.46, p = .008). In healthy controls, cortisol slope correlated with platelet activity for CD40 (r = -0.43, p = .048) and 5-HT was correlated with CD40L (r = 0.53, p = .007). In patients with both T2DM and MD, 5-HT and CD62P were correlated (r = 0.52, p = .033). CONCLUSIONS: Increased platelet activity in T2DM and MD may play a role in the association between diabetes, depression, and coronary artery disease. The present data suggest that group differences in cortisol or 5-HT as well as group-specific associations of cortisol or 5-HT with platelet markers might be of limited importance in the shared pathways of T2DM and depression in the pathophysiology of coronary artery disease.

A Preliminary Study on the Relationship between Platelet Serotonin Transporter Functionality, Depression, and Fatigue in Patients with Untreated Chronic Hepatitis C.

Objective and Methods. Although the interaction between fatigue and depression in patients with chronic hepatitis C infection (HCV) has been recognized, the biological correlates of this observation have yet to be reported. We addressed this issue by examining serotonin transporter- (SERT-) driven [(14)C]-serotonin uptake rate (SUR) and serotonin content in platelets of 65 untreated HCV patients and 65 healthy control subjects (HCS). All patients completed report questionnaires for fatigue, depression, and general psychopathology. Structured interviews were conducted by a board-certified psychiatrist. Results. Whereas 36 of the patients experienced fatigue of moderate-to-severe intensity, only 16 reported symptoms of depression (BDI score > 10). Mean SUR in patients with depressive symptoms was significantly higher relative to the HCS, corresponding to a large Cohen's effect size of d = 1.45 (95% CI = 0.66-1.83). Patients who rated their fatigue to have a marked impact on mood and activity displayed a moderate relationship between the BDI score and SUR (n = 18, r = 0.563, P = 0.015), which becomes stronger after controlling for age, gender, and thrombocytopenia (r part = 0.710, P = 0.003). In the univariate analysis, high fatigue interference score, thrombocytopenia, and high SUR were all significant predictors of depression. Conclusions. High SERT activity could be implicated in the expression of depressive symptoms especially in a subgroup of HCV patients who are feeling fatigue as markedly distressing.

The 5-HTTLPR polymorphism, platelet serotonin transporter activity and platelet serotonin content in underweight and weight-recovered females with anorexia nervosa.

Serotonin (5-HT) pathways play an important role in the pathophysiology of anorexia nervosa (AN). In this study, we investigated functional characteristics of the platelet 5-HT transporter and platelet 5-HT content in AN patients at various stages of their illness in comparison to healthy control woman (HCW) controlling for the 5-HTTLPR deletion/insertion polymorphism and other confounding variables. Fasting blood samples of 58 acutely underweight AN patients (acAN, BMI = 15.2 ± 1.4), 26 AN patients of the initial acAN sample after short-term/partial weight restoration (BMI = 17.3 ± 0.9), 36 weight-recovered AN patients (recAN, BMI = 20.7 ± 2.2) and 58 HCW (BMI = 21.6 ± 2.0) were assessed for kinetic characteristics of platelet 5-HT uptake (V (max), K (m)) and platelet 5-HT content. Plasma leptin served as an indicator of malnutrition. Mean V (max) and K (m) values were significantly higher in recAN subjects in comparison to HCW (2.05 ± 0.62 vs. 1.66 ± 0.40 nmol 5-HT/10(9) platelets min and 432 ± 215 vs. 315 ± 136 nmol, respectively) but there were no differences in platelet 5-HT content (464.8 ± 210.6 vs. 472.0 ± 162.2 ng 5-HT/10(9) platelets). 5-HT parameters in acAN patients and HCW were similar. 5-HTTLPR variants were not related to 5-HT platelet variables. In the longitudinal part of the study we found significantly increased 5-HT content but unchanged 5-HT uptake in AN patients after short-term/partial weight restoration. Our results highlight the importance of malnutrition for the interpretation of abnormalities in neurotransmitter systems in AN. Changes in platelet 5-HT transporter activity were related to the stage of the illness but not to 5-HTTLPR genotype. Increased V (max) and K (m) in recovered AN patients might mirror adaptive modulations of the 5-HT system.

Serotonin transporter activity and serotonin concentration in platelets of patients with irritable bowel syndrome: effect of gender.

BACKGROUND: In the past decade, a strong argument has been built for the role of serotonin (5HT) and the serotonin transporter (SERT) in irritable bowel syndrome (IBS). However, it is still not clear how SERT contributes to this clinically heterogeneous disease. The present study addressed this issue by implementing platelet (plt) markers of SERT activity in the assessment protocol. METHODS: Fasting blood samples of 149 (51 male/98 female) subjects with Rome II and III defined IBS subtypes, and 163 healthy control subjects (CSs; 75 male/88 female) were analyzed for platelet 5HT concentration and 5HT uptake activity [maximum uptake rate (V (max)) and affinity constant (K (m))]. RESULTS: Gender had a significant impact on platelet markers of SERT activity. Male IBS patients showed significantly lower median V (max) and K (m) values than the male CS (V (max) 1.706 vs. 2.148 nmol/10(9) plts x min, P < 0.001; K (m) 346 vs. 410 nmol, P = 0.008) without any significant reduction in platelet 5HT concentration (362 vs. 394 ng/10(9) plts). On the other hand, V (max) values were not different between female IBS patients and female CS (1.642 vs. 1.741 nmol/10(9) plts x min), but platelet 5HT concentration was significantly lower in females with diarrhea-predominant IBS (363 vs. 435 ng/10(9) plts, P < 0.05). CONCLUSION: Although an absolute extrapolation from platelets to the gastrointestinal tissue does not appear to be justified, our findings demonstrated that the contribution of disturbed SERT activity to IBS is not uniform and is possibly gender-specific. The results suggest that an assessment of SERT function in platelets may help to elucidate the differences between IBS patients in response to drugs affecting the 5HT system.

Serum brain-derived neurotrophic factor and peripheral indicators of the serotonin system in underweight and weight-recovered adolescent girls and women with anorexia nervosa.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) mutant mice show hyperphagia and hyperleptinemia. Animal and cell-culture experiments suggest multiple interrelations between BDNF and the serotonin (5-HT) system. We studied serum BDNF in patients with anorexia nervosa and its associations with peripheral indicators of the 5-HT system. To control for secondary effects of acute malnutrition, we assessed acutely underweight patients with anorexia nervosa (acAN) in comparison to long-term weight-recovered patients with the disorder (recAN) and healthy controls. METHODS: We determined serum BDNF, platelet 5-HT content and platelet 5-HT uptake in 33 patients in the acAN group, 20 patients in the recAN group and 33 controls. Plasma leptin served as an indicator of malnutrition. RESULTS: Patients in the acAN group were aged 14-29 years and had a mean body mass index (BMI) of 14.9 (standard deviation [SD] 1.4) kg/m(2). Those in the recAN group were aged 15-29 years and had a mean BMI of 20.5 (SD 1.3) kg/m(2) and the controls were aged 15-26 years and had a BMI of 21.4 (SD 2.1) kg/m(2). The mean serum BDNF levels were significantly increased in the recAN group compared with the acAN group (8820, SD 3074 v. 6161, SD 2885 pg/mL, U = 154.5, p = 0.001). There were no significant associations between BDNF and either platelet 5-HT content or platelet 5-HT uptake. Among patients with anorexia nervosa, we found significant positive linear relations between BDNF and BMI (r = 0.312, p = 0.023) and between BDNF and leptin (r = 0.365, p = 0.016). LIMITATIONS: We measured the signal proteins under study in peripheral blood. CONCLUSION: Serum BDNF levels in patients with anorexia nervosa depend on the state of illness and the degree of hypoleptinemia. Upregulation of BDNF in weight-recovered patients with anorexia nervosa could be part of a regenerative process after biochemical and molecular neuronal injury due to prolonged malnutrition. Associations between the BDNF and the 5-HT system in humans remain to be established.

Aromatic amino acids in weight-recovered females with anorexia nervosa.

OBJECTIVE: Most previous studies investigating amino acid levels in anorexia nervosa (AN) have focused on acutely underweight patients. The present study assessed the availability of aromatic amino acids in the plasma of weight-recovered outpatients with AN (recAN) in comparison to acutely underweight AN patients (acAN) and healthy control woman (HCW). METHOD: Plasma tryptophan (TRP), tyrosine (TYR), and phenylalanine (PHEN) as well as leptin concentration were determined in 32 recAN, 32 acAN, and 32 HCW. RESULTS: Both recAN and acAN patients showed significantly lower levels of TRP and PHEN when compared to HCW. TYR was reduced in acAN patients only. DISCUSSION: Normal weight and normal leptin levels but lower availability of TRP and PHEN in recAN patients might indicate that outside a tightly controlled setting these patients still engage in abnormal eating patterns. Reduced peripheral availability of these precursor amino acids could impact on 5-HT and catecholamine functioning in the brain.

Three cases of successful tryptophan add-on or monotherapy of hepatitis C and IFNalpha-associated mood disorders.

BACKGROUND: Interferon-alpha (IFN(alpha))-associated mood disorder is a major complication of treatment for chronic hepatitis C. METHOD: The authors report on three patients infected with chronic hepatitis C showing severe depressive symptoms during or after IFN(alpha) treatment. Because patients had lowered tryptophan blood levels and did not response to antidepressants, they received tryptophan up to a dosage of 1,000 mg/day as mono- or add-on treatment. RESULTS: Tryptophan, used as augmentation or monotherapeutic treatment, led to a significant improvement of depressive symptoms in all three patients. CONCLUSION: A tryptophan deficit seems to be involved in the pathophysiology of persistent mood changes during and after IFN(alpha) treatment.

S100B in underweight and weight-recovered patients with anorexia nervosa.

Anorexia nervosa (AN) commonly arises during adolescence, leading to interruptions of somatic and psychological development as well as to cortical atrophy and reductions of brain volume. While most brain changes shift towards normal with weight restoration, it is not certain whether they are related to the loss of brain cells, neuropil or merely due to fluid shifts. We measured S100B serum concentrations and psychometric characteristics in 34 patients with acute AN, 19 weight-recovered patients and 35 healthy control women (HCW). Plasma tryptophan and leptin levels were determined as markers for malnutrition and neuroendocrine adaptation to semi-starvation. Peripheral S100B concentrations of acute and former AN patients were not elevated and not statistically different from HCW. BMI, peripheral leptin levels and measures of psychopathology as well as executive cognitive functioning did not correlate with S100B. Plasma tryptophan was positively related to S100B. Our results are in line with our previous findings showing unaltered GFAP and NSE plasma levels in patients with acute AN. Together they do not support hypotheses comprising the degeneration of glial or neuronal cells to explain common signs of brain atrophy in patients with acute AN.

Increased activity of serotonin uptake in platelets in medication overuse headache following regular intake of analgesics and triptans.

We investigated the effect of chronic administration of different pain medications on the activity of the serotonin transporter (SERT) in patients with medication overuse headache (MOH). We measured the kinetic of platelet 5-HT uptake (maximal velocity, Vmax and the Michaelis-Menten constant, Km in patients with overuse of triptans (tMOH, n = 15) or analgesics (aMOH, n = 14) before and after drug withdrawal, as well as in headache-free healthy subjects (n = 15) and patients with episodic migraine (EM, n = 16). Vmax was increased similarly in both, tMOH and aMOH compared to healthy subjects and patients with EM and normalized after withdrawal in parallel to the improvement of headache frequency. Average Km was similar in all groups at baseline and not affected by the withdrawal. The data demonstrate a transient increase of SERT activity in patients with analgesic and triptan induced MOH but do not allow to differentiate whether the increase of serotonin uptake is caused by regular intake of analgesics or triptans or is a consequence of frequent headache attacks.

Brain and platelet serotonin transporter in humans-correlation between [123I]-ADAM SPECT and serotonergic measurements in platelets.

Blood platelets are thought to be a useful peripheral model for investigating the central serotoninergic mechanisms associated with the serotonin transporter (SERT). On the other hand, an in vivo investigation of SERT in the human brain has been made possible by the development of several promising SPECT radioligands, such as [123I]-ADAM. The aim of the present study was to investigate the possible correlation between the SERT measurements in the brain and those in platelets. Forty-four subjects (14 healthy subjects and 30 patients with the diagnosis of major depression or schizoaffective disorder) were examined. The [123I]-ADAM binding was assessed 4h after injection using MR-guided regions of interest (ROIs) in the midbrain and cerebellum. In a parallel investigation, serotonin (5HT) concentration and kinetic characteristics of 5HT uptake activity (Vmax and Km) were determined in platelet-rich plasma. Overall, there was no significant correlation between the V(max) of 5HT uptake in platelets and the specific to nonspecific partition coefficient of [123I]-ADAM (V''3) in the midbrain. However, low but significant Pearson correlation coefficients were found for V(max) and normalised activities measured in the midbrain (r=0.310, p=0.043). The correlation was stronger and significant in females (n=20, r=0.629, p=0.003) but low and non-significant in the 24 males (r=0.104). Although confirmation is necessary, it seems that the relationship between different indices of [123I]-ADAM binding in the brain and 5HT uptake characteristics in platelets is complex, nonuniform, and possibly gender-specific.

Impact of the CYP2D6 ultra-rapid metabolizer genotype on doxepin pharmacokinetics and serotonin in platelets.

INTRODUCTION: CYP2D6 gene duplication causing ultrafast metabolism is one reason for failure in responding to CYP2D6-metabolized antidepressants. We studied the effect of the CYP2D6 duplication genotype on doxepin pharmacokinetics and platelet serotonin uptake and concentrations. METHODS: Pharmacokinetics of trans (E)- and cis (Z)-doxepin and N-desmethyldoxepin were analyzed after a single dose of 75 mg doxepin in 11 ultrafast metabolizers (UM), 11 extensive metabolizers (EM) and 3 poor metabolizers (PM), identified by genotyping for CYP2D6 alleles *2, *3, *4, *5, *6, *9, *10, *35, *41 and specific analyses to characterize gene duplication. Platelet serotonin concentrations were measured by HPLC. RESULTS: A trend for lower AUC of the active principle (sum of doxepin and N-desmethyldoxepin) in UMs versus EMs was detected (575 versus 1,000 nmol h/l, P=0.07), mainly due to the differences in desmethyldoxepin concentrations (P=0.003). Stereoselective analysis showed a significant effect of the UM genotype on (E)-doxepin pharmacokinetic parameters whereas those of (Z)-doxepin did not differ between the CYP2D6 genotype groups. The 75-mg doxepin dose had no effect on platelet serotonin concentration and uptake, but serotonin concentrations in platelets were significantly higher in UM in comparison to the EM and PM groups. At baseline, these concentrations were 462, 399, and 292 ng/10 platelets in UM, EM and PM (P<0.0001 for trend). CONCLUSIONS: At the same dose, internal exposure to doxepin differed by more than ten-fold between the CYP2D6 genotype groups. CYP2D6 may have an effect on platelet serotonin explained by salvage pathways of 5-methoxytryptamine to serotonin mediated by CYP2D6; however, this finding requires further confirmatory experiments.

Platelet-5HT uptake and gastrointestinal symptoms in patients suffering from major depression.

The objective of this study was to determine whether the presence of gastrointestinal symptoms, as defined by item 12 of Hamilton-Rating-Scale for Depression, is related to kinetic characteristics of platelet-5HT uptake in patients with major depression. The clinical picture of depression in patients with severe form of appetite loss with difficulties of eating (item 12 = 2) and weight loss was characterized by the combination of depressed mood with somatic symptoms of anxiety, sleep disturbances, decreased activity and the presence of nausea. The high frequency of relatively low Vmax and Km of 5HT uptake in this group (n = 12), all in the lower range of controls, resulted in significantly lower mean values compared with patients without gastrointestinal symptoms (n = 16; item 12 = 0) or 57 healthy subjects (Vmax = 1.36 +/- 0.27 vs. 2.14 +/- 0.85 vs. 2.05 +/- 0.74 nMol 5HT/10(9)plat.x min; Km = 382 +/- 68 vs. 467 +/- 94 vs. 492 +/- 123 nM respectively). Although our finding needs confirmation, it seems that in the research for serotonergic mechanisms in major depression, it makes sense to look at depressed patients with or without somatic symptoms separately. Based on findings in 5HT transporter knock-out mice (J. Neurosci. 15 (2001) 6348), we assume that the low apparent Vmax of platelet-5HT uptake reflects the low expression of 5HT transporter not only in platelets, but also in the gut mucosa and enteric serotonergic neurons, which probably increases the risk of typical gastrointestinal symptoms such as appetite loss and nausea occurring in some depressed patients.

High platelet-serotonin uptake activity is associated with a rapid response in depressed patients treated with amitriptyline.

Based on the assumption that there is a biological basis behind the individual differences in the speed with which an antidepressant produces its therapeutic effects, we compared initial serotonin (5HT) uptake characteristics in platelets of rapid (2 weeks), slow (4 weeks) and non-responders in a group of 47 depressed patients who were treated with amitriptyline for at least 4 weeks. A response was defined as a reduction in the Hamilton Depression Rating Scale score of > or =50% from baseline. In 16 rapid responders, a significantly higher mean 5HT uptake efficiency (Vmax/Km) corresponded with a significantly higher 5HT uptake activity at a low, physiological substrate concentration in comparison with the 15 non-responders or the 16 slow responders (33.1+/-7.8 versus 25.5+/-7.7 versus 24.1+/-5.8 pMol [3H]-5HT/10(9) plat. x 5 min, respectively). The findings indicate that pre-treatment 5HT uptake activity contributes to the individual variability in response time to amitriptyline treatment.

Suicidality, impulsivity and aggression--is there a link to 5HIAA concentration in the cerebrospinal fluid?

In biological suicide research, low cerebrospinal fluid-5-hydroxyindolacetic acid (CSF-5HIAA) concentrations have been associated with suicidality, aggression and impulsivity. However, it frequently appears that the interpretation of existing study results is flawed. The analysis of various published findings suggests that contaminating factors like impulsivity or depressive symptoms in suicide attempters are often not taken into consideration at the time of suicide. The seemingly 'robust' association of low CSF-5HIAA concentration with 'suicidality' and 'aggression' is in fact rather weak. Reported associations of subgroups of suicidal behavior (e.g. violent suicide attempts) with low CSF-5HIAA concentrations are likely to represent somewhat premature translations of findings from studies that have flaws in methodology. Furthermore, the perception of 'suicidal behavior' as autoaggressive behavior or inwardly directed aggression in the view of the authors may not be useful in biological suicide research. The construct of aggressivity is insufficiently defined, resulting in difficulties to interpret empirical data. Some evidence exists, however, that reduced CSF-5HIAA concentrations might be related to certain depressive symptoms and changes in impulsivity. More carefully designed studies are required to overcome the existing methodological shortcomings.