Métrologie de la douleur animale : validation sur des modèles de douleur viscérale bovine et articulaires canins

La douleur est une expérience multidimensionnelle comportant des aspects sensoriels, émotionnels et cognitifs. Théoriquement, des méthodes de mesures comportementales, physiologiques, neurophysiologiques et sensorielles peuvent quantifier la douleur. Peu d’études ont étudié la validation des mesures utilisées en médecine vétérinaire. La recherche combine les travaux de Maîtrise et de Doctorat, traite en partie de la validité de méthodes. Dans cet objectif, nos travaux de recherche étudiaient la validité de méthodes comportementales, physiologiques et neurophysiologiques usuelles pour la mesure de la douleur en comparant les expressions de douleur (vache et chien) chez des animaux contrôle par comparaison à des animaux sous analgésie préventive ou sous traitement curatif suivant une douleur induite par chirurgie (modèles de douleur viscérale bovine ou orthopédique canine) ou causée par une maladie naturelle (arthrose canine). Une première étude comparait les mesures de la douleur entre les vaches du groupe placebo et celles sous analgésie postopératoire sur une durée de 21 jours suivant l’induction d’une douleur viscérale chronique. Les vaches du groupe placebo ont présenté une plus forte sensibilité à la douleur et une diminution de la noradrénaline et de la transthyrétine mesurées dans le liquide cérébro-spinal, une diminution de l’activité motrice (AM) (moindre que dans les groupes avec analgésie), de l’agitation enregistrée par vidéo-analyse et une augmentation du stress selon la mesure de l’activité électrodermique (AED). Les méthodes d’intérêt identifiées étaient les marqueurs spinaux, la mesure de la sensibilisation, de comportements par vidéo-analyse et de l’AM par bio-télémétrie. En utilisant des méthodes semblables à celles précédemment décrites, deux études expérimentales de douleur orthopédique ont été réalisées afin de comparer les réponses à la douleur entre des chiens traités avec une analgésie préventive (opioïdes et anti-inflammatoires, étude #2) ou un biphosphonate (tiludronate, étude #3) par comparaison à des chiens contrôles. Seules les échelles de douleur étaient différentes entre les études de recherche. Pour l’étude #2, les ii chiens sous analgésie ont présenté de plus faibles scores de douleur mesurés avec l’échelle de douleur nommée 4A-VET et ceci simultanément à une faible réponse de l’AED une heure après la chirurgie de trochléoplastie. La fréquence du comportement spontané de ‘la marche avec plein appui de la patte opérée’ mesurée à l’aide de la vidéo-analyse augmentait chez les chiens sous analgésie préventive 24 heures après la chirurgie. L’étude #3 démontrait surtout l’apparition de sensibilisation centrale (à la fois par l’évaluation sensorielle quantitative et les marqueurs spinaux) chez les chiens contrôle, 56 jours après l’induction d’arthrose chirurgicale. Ainsi, les chiens traités avec le tiludronate ont présenté une différence sur la substance P et la transthyrétine cérébro-spinale, une diminution de la sensibilisation périphérique, plus d’appui de la patte opérée lors de la marche selon la mesure du pic de force verticale (PFV), une augmentation de la fréquence de ‘la marche avec plein appui de la patte opérée’. La sensibilisation centrale était associée à la diminution de PFV, et une augmentation de l’AED et du comportement spontané de ‘la marche avec plein appui de la patte opérée’. Pour l’étude #4, la validité et la sensibilité des méthodes ont été évaluées dans une condition d’arthrose naturelle chez des chiens traités avec une diète enrichie en moule verte, un produit ayant des effets anti-inflammatoires et chondroprotecteurs attendus. Les chiens traités présentaient une diminution des scores de douleur via l’échelle nommée CSOM, une augmentation de PFV et une augmentation de l’AM. Dans l’ensemble, les résultats confirment que la vidéo-analyse évaluait la douleur de façon objective et pour des modèles différents de douleur et les marqueurs spinaux sont prometteurs. Le PFV était spécifique de la douleur orthopédique. La sensibilisation était présente lors de douleur pathologique. L’AED n’est pas valide pour la mesure de la douleur. La baisse d’AM suggèrerait un comportement de douleur. Les études étaient exploratoires pour les échelles de douleur en raison de leur niveau (débutant) de développement et du manque d’informations sur les qualités métrologiques de ces mesures.

Différentes approches dans le traitement de la dépression post-infarctus du myocarde : effet de la desvenlafaxine et des probiotiques

Plusieurs études ont montré que les maladies cardiovasculaires constituent un risque majeur de développement du trouble dépressif chez l’homme. Plus précisément, à la suite d’un infarctus du myocarde, 15 à 30 % des patients développent une dépression majeure dans les 6 à 8 mois suivant l’évènement cardiaque. Dans un modèle d’infarctus du myocarde chez le rat, développé dans notre laboratoire, nous avons noté la présence de comportements compatibles avec une dépression, deux semaines après l’infarctus. Nous avons également détecté des cellules apoptotiques dans le système limbique dès les premières minutes de reperfusion, nombre qui atteint son apogée à 3 jours de reperfusion. Nous avions émis l’hypothèse que l’apoptose que l’on observe dans le système limbique serait reliée à la réponse inflammatoire induite par l’infarctus du myocarde. Les comportements reliés à de la dépression ont été prévenus par l’administration d’un inhibiteur de la synthèse des cytokines pro-inflammatoires, la pentoxifylline, le célécoxib, un inhibiteur de la cyclooxygenase-2, par des probiotiques ainsi que par différents antidépresseurs. Les résultats des deux premières études de cette thèse montrent que la desvenlafaxine, un Inhibiteur de la recapture de la sérotonine et noradrénaline (IRSN) prévient les comportements dépressifs tout en diminuant l’apoptose à 3 jours post-infarctus dans le système limbique. Les comportements similaires à ceux d’une dépression que présentent les rats deux semaines après l’évènement cardiaque sont encore présents à 4 mois post-infarctus, si aucun traitement n’est entrepris. De plus, ces animaux développent des troubles d’apprentissage que la desvenlafaxine peut prévenir, et ceci même si le traitement n’est présent que pendant les 2 premières semaines post-infarctus. Dans la troisième étude de cette thèse, nous avons voulu savoir si le nerf vague était impliqué dans les effets bénéfiques de deux probiotiques sur l’apoptose dans le système limbique après un infarctus du myocarde. Nos résultats ont démontré que les probiotiques réduisent l’apoptose dans le système limbique après un infarctus du myocarde, mais que cet effet est perdu en présence d’une vagotomie. Les résultats obtenus démontrent que l’infarctus du myocarde induit une mort par apoptose dans le système limbique de même que des comportements dépressifs et des problèmes d’apprentissage à long terme. Ces problèmes peuvent être diminués par un traitement à la desvenlafaxine, et ceci même si le traitement n’est présent que pour les deux premières semaines post-infarctus. Finalement, nous avons observé que les probiotiques avaient des effets bénéfiques sur l’apoptose dans le système limbique par un mécanisme impliquant le nerf vague. En conclusion, plusieurs interventions différentes sont efficaces pour limiter les conséquences de l’infarctus du myocarde sur le système limbique et un traitement court est efficace pour prévenir les problèmes à plus long terme.

Thyroid function in pyridoxine-deficient young rats

In pyridopaminedoxine-deficient young rats hypothalamic serum TSH concentration was detected. Highly signifiserotonin was decreased with no changes in the cant decreases in the content of pituitary TSH and in and noradrenaline content. Serum the number of pituitary thyrotroph secretory granules and tri-iodothyronine concentrations were were found. These results suo mmuuchch lower in the deficient rats as compared to thyroidism of suggest that the hypocontrols. No significant of hypothalamicp yorirdigoxinin.e -deficient young rats might bbee difference between deficient and control groups in the

Efectos de la asociación vasopresina-noradrenalina en pacientes pediátricos con choque séptico refractario

Objetivo: Evaluar el efecto sobre presión arterial media (PAM), estancia hospitalaria, mortalidad y perfusión tisular con el uso de vasopresores en niños con choque séptico refractario en la Unidad de Cuidado Intensivo pediátrico de la Fundación CardioInfantil. Materiales y Métodos: Estudio observacional de cohorte retrospectiva en niños de 1 mes a 18 años con choque séptico refractario atendidos de enero 2008 a diciembre 2013 tratados con noradrenalina sola ó vasopresina-noradrenalina. Se excluyeron pacientes con choque de otra etiología, cardiopatías congénitas, diabetes insípida y muerte encefálica. Se estimaron, como medidas de asociación riesgos relativos con sus respectivos intervalos de confianza al 95%.Resultados: Se evaluaron 129 pacientes, de los cuales 51% eran niños, edad promedio 52 meses con una mortalidad global del 34.1%. La PAM inicial en ambos grupos mostró incremento significativo que se mantuvo en las siguientes 3 horas (p<0,005). La mortalidad en el grupo PRISM III de bajo riesgo fue menor con la noradrenalina sola (p<0,005 RR3,7 IC95% 1,16-12,2) pero igual en ambos grupos en los de riesgo moderado según esta escala(p=0,42 RR 0,88 IC95% 0,60-1,30). No se encontraron diferencias estadísticamente significativas en estancia en UCIP (p=0,79) ni hospitalaria total (p=0,96) pero sí mejoría en función hepática (p=0,004)y renal (p<0,005) del grupo de vasopresina-noradrenalina Conclusiones: La asociación vasopresina-noradrenalina mejora la PAM cuando no se han alcanzado metas con un solo vasopresor en pacientes con choque séptico refractario. Se necesitan estudios prospectivos que corroboren estos hallazgos. Palabras claves:Choque séptico refractario, noradrenalina, vasopresina, mortalidad.

G protein ss gamma subunits mediate presynaptic inhibition of transmitter release from rat superior cervical ganglion neurones in culture

The activation of presynaptic G protein-coupled receptors (GPCRs) is widely reported to inhibit transmitter release; however, the lack of accessibility of many presynaptic terminals has limited direct analysis of signalling mediators. We studied GPCR-mediated inhibition of fast cholinergic transmission between superior cervical ganglion neurones (SCGNs) in culture. The adrenoceptor agonist noradrenaline (NA) caused a dose-related reduction in evoked excitatory postsynaptic potentials (EPSPs). NA-induced EPSP decrease was accompanied by effects on the presynaptic action potential (AP), reducing AP duration and amplitude of the after-hyperpolarization (AHP), without affecting the pre- and postsynaptic membrane potential. All effects of NA were blocked by yohimbine and synaptic transmission was reduced by clonidine, consistent with an action at presynaptic alpha 2-adrenoceptors. NA-induced inhibition of transmission was sensitive to pre-incubation of SCGNs with pertussis toxin (PTX), implicating the involvement of G alpha(i)/(o)beta y subunits. Expression of G alpha transducin, an agent which sequesters G protein beta gamma (G beta y) subunits, in the presynaptic neurone caused a time-dependent attenuation of NA-induced inhibition. Injection of purified G beta gamma subunits into the presynaptic neurone inhibited transmission, and also reduced the AHP amplitude. Furthermore, NA-induced inhibition was occluded by pre-injection of G beta gamma subunits. The Ca2+ channel blocker Cd2+ mimicked NA effects on transmitter release. Cd2+, NA and G beta gamma subunits also inhibited somatic Ca2+ current. In contrast to effects on AP-evoked transmitter release, NA had no clear action on AP-independent EPSPs induced by hypertonic solutions. These results demonstrate that G beta gamma subunits functionally mediate inhibition of transmitter release by alpha 2-adrenoceptors and represent important regulators of synaptic transmission at mammalian presynaptic terminals.

Inhibition of synaptic transmission and G protein modulation by synthetic CaV2.2 Ca2+ channel peptides

Abstract: Modulation of presynaptic voltage-dependent Ca+ channels is a major means of controlling neurotransmitter release. The CaV 2.2 Ca2+ channel subunit contains several inhibitory interaction sites for Gβγ subunits, including the amino terminal (NT) and I–II loop. The NT and I–II loop have also been proposed to undergo a G protein-gated inhibitory interaction, whilst the NT itself has also been proposed to suppress CaV 2 channel activity. Here, we investigate the effects of an amino terminal (CaV 2.2[45–55]) ‘NT peptide’ and a I–II loop alpha interaction domain (CaV 2.2[377–393]) ‘AID peptide’ on synaptic transmission, Ca2+ channel activity and G protein modulation in superior cervical ganglion neurones (SCGNs). Presynaptic injection of NT or AID peptide into SCGN synapses inhibited synaptic transmission and also attenuated noradrenaline-induced G protein modulation. In isolated SCGNs, NT and AID peptides reduced whole-cell Ca2+ current amplitude, modified voltage dependence of Ca2+ channel activation and attenuated noradrenaline-induced G protein modulation. Co-application of NT and AID peptide negated inhibitory actions. Together, these data favour direct peptide interaction with presynaptic Ca2+ channels, with effects on current amplitude and gating representing likely mechanisms responsible for inhibition of synaptic transmission. Mutations to residues reported as determinants of Ca2+ channel function within the NT peptide negated inhibitory effects on synaptic transmission, Ca2+ current amplitude and gating and G protein modulation. A mutation within the proposed QXXER motif for G protein modulation did not abolish inhibitory effects of the AID peptide. This study suggests that the CaV 2.2 amino terminal and I–II loop contribute molecular determinants for Ca2+ channel function; the data favour a direct interaction of peptides with Ca2+ channels to inhibit synaptic transmission and attenuate G protein modulation. Non-technical summary: Nerve cells (neurones) in the body communicate with each other by releasing chemicals (neurotransmitters) which act on proteins called receptors. An important group of receptors (called G protein coupled receptors, GPCRs) regulate the release of neurotransmitters by an action on the ion channels that let calcium into the cell. Here, we show for the first time that small peptides based on specific regions of calcium ion channels involved in GPCR signalling can themselves inhibit nerve cell communication. We show that these peptides act directly on calcium channels to make them more difficult to open and thus reduce calcium influx into native neurones. These peptides also reduce GPCR-mediated signalling. This work is important in increasing our knowledge about modulation of the calcium ion channel protein; such knowledge may help in the development of drugs to prevent signalling in pathways such as those involved in pain perception.

Diminished neural processing of aversive and rewarding stimuli during selective serotonin reuptake inhibitor treatment

Background Selective serotonin reuptake inhibitors (SSRIs) are popular medications for anxiety and depression, but their effectiveness, particularly in patients with prominent symptoms of loss of motivation and pleasure, has been questioned. There are few studies of the effect of SSRIs on neural reward mechanisms in humans. Methods We studied 45 healthy participants who were randomly allocated to receive the SSRI citalopram, the noradrenaline reuptake inhibitor reboxetine, or placebo for 7 days in a double-blind, parallel group design. We used functional magnetic resonance imaging to measure the neural response to rewarding (sight and/or flavor of chocolate) and aversive stimuli (sight of moldy strawberries and/or an unpleasant strawberry taste) on the final day of drug treatment. Results Citalopram reduced activation to the chocolate stimuli in the ventral striatum and the ventral medial/orbitofrontal cortex. In contrast, reboxetine did not suppress ventral striatal activity and in fact increased neural responses within medial orbitofrontal cortex to reward. Citalopram also decreased neural responses to the aversive stimuli conditions in key “punishment” areas such as the lateral orbitofrontal cortex. Reboxetine produced a similar, although weaker effect. Conclusions Our findings are the first to show that treatment with SSRIs can diminish the neural processing of both rewarding and aversive stimuli. The ability of SSRIs to decrease neural responses to reward might underlie the questioned efficacy of SSRIs in depressive conditions characterized by decreased motivation and anhedonia and could also account for the experience of emotional blunting described by some patients during SSRI treatment.

Adrenergic receptor stimulation of the mitogen-activated protein kinase cascade and cardiac hypertrophy.

Phenylephrine and noradrenaline (alpha-adrenergic agonism) or isoprenaline (beta-adrenergic agonism) stimulated protein synthesis rates, increased the activity of the atrial natriuretic factor gene promoter and activated mitogen-activated protein kinase (MAPK). The EC50 for MAPK activation by noradrenaline was 2-4 microM and that for isoprenaline was 0.2-0.3 microM. Maximal activation of MAPK by isoprenaline was inhibited by the beta-adrenergic antagonist, propranolol, whereas the activation by noradrenaline was inhibited by the alpha1-adrenergic antagonist, prazosin. FPLC on a Mono-Q column separated two peaks of MAPK (p42MAPK and p44MAPK) and two peaks of MAPK-activating activity (MEK) activated by isoprenaline or noradrenaline. Prolonged phorbol ester exposure partially down-regulated the activation of MAPK by noradrenaline but not by isoprenaline. This implies a role for protein kinase C in MAPK activation by noradrenaline but not isoprenaline. A role for cyclic AMP in activation of the MAPK pathway was eliminated when other agonists that elevate cyclic AMP in the cardiac myocyte did not activate MAPK. In contrast, MAPK was activated by exposure to ionomycin, Bay K8644 or thapsigargin that elevate intracellular Ca2+. Furthermore, depletion of extracellular Ca2+ concentrations with bis-(o-aminophenoxy)ethane-NNN'N'-tetra-acetic acid (BAPTA) or blocking of the L-type Ca2+ channel with nifepidine or verapamil inhibited the response to isoprenaline without inhibiting the responses to noradrenaline. We conclude that alpha- and beta-adrenergic agonists can activate the MEK/MAPK pathway in the heart by different signalling pathways. Elevation of intracellular Ca2+ rather than cyclic AMP appears important in the activation of MAPK by isoprenaline in the cardiac myocyte.

Ovarian-Steroid Modulation of Locus Coeruleus Activity in Female Rats: Involvement in Luteinising Hormone Regulation

The noradrenergic nucleus locus coeruleus (LC) has been reported to regulate luteinising hormone (LH) secretion in female rats. Both oestrogen and progestin receptors have been demonstrated in LC neurones, suggesting that these cells are possibly responsive to variations in circulating levels of ovarian steroids. We therefore evaluated changes in the activity of LC neurones during the oestrous cycle and after ovarian-steroid treatment in ovariectomised (OVX) rats, as determined by immunoreactivity to Fos-related antigens (FRA), which comprises all of the known members of the Fos family. Effects of ovarian steroids on the firing rate of LC neurones were also determined in a slice preparation. The number of FRA/tyrosine hydroxylase (TH)-immunoreactive (ir) neurones in the LC increased from 14.00-16.00 h on pro-oestrus, coinciding with the onset of the LH surge and rise in plasma progesterone. FRA immunoreactivity was unaltered during dioestrus. Oestradiol-treated OVX rats (OVX+E) displayed marked reduction in FRA/TH-ir neurones in LC compared to oil-treated OVX rats. Accordingly, oestradiol superfusion significantly reduced the spontaneous firing rate of LC neurones in slices from OVX rats. Compared to OVX+E, oestradiol-treated rats injected with progesterone at 08.00 h (OVX+EP) exhibited higher number of FRA/TH-ir neurones in the LC at 10.00 h and 16.00 h, and great amplification of the LH surge. Bath application of progesterone significantly increased the spontaneous firing rate of OVX+E LC neurones. Our data suggest that ovarian steroids may physiologically modulate the activity of LC neurones in females, with possible implications for LH secretion. Moreover, oestradiol and progesterone appear to exert opposite and complementary effects (i.e. whereas oestradiol inhibits, progesterone, after oestradiol priming, stimulates LC activity).

NEONATAL HANDLING AND THE MATERNAL ODOR PREFERENCE IN RAT PUPS: INVOLVEMENT OF MONOAMINES AND CYCLIC AMP RESPONSE ELEMENT-BINDING PROTEIN PATHWAY IN THE OLFACTORY BULB

Early-life environmental events, such as the handling procedure, can induce long-lasting alterations upon several behavioral and neuroendocrine systems. However, the changes within the pups that could be causally related to the effects in adulthood are still poorly understood. In the present study, we analyzed the effects of neonatal handling on behavioral (maternal odor preference) and biochemical (cyclic AMP response element-binding protein (CREB) phosphorylation, noradrenaline (NA), and serotonin (5-HT) levels in the olfactory bulb (OB)) parameters in 7-day-old male and female rat pups. Repeated handling (RH) abolished preference for the maternal odor in female pups compared with nonhandled (NH) and the single-handled (SH) ones, while in RH males the preference was not different than NH and SH groups. In both male and female pups, RH decreased NA activity in the OB, but 5-HT activity increased only in males. Since preference for the maternal odor involves the synergic action of NA and 5-HT in the OB, the maintenance of the behavior in RH males could be related to the increased 5-HT activity, in spite of reduction in the NA activity in the OB. RH did not alter CREB phosphorylation in the OB of both male and females compared with NH pups. The repeated handling procedure can affect the behavior of rat pups in response to the maternal odor and biochemical parameters related to the olfactory learning mechanism. Sex differences were already detected in 7-day-old pups. Although the responsiveness of the hypothalamic-pituitary-adrenal axis to stressors is reduced in the neonatal period, environmental interventions may impact behavioral and biochemical mechanisms relevant to the animal at that early age. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.

DAILY VARIATION OF CONSTITUTIVELY ACTIVATED NUCLEAR FACTOR KAPPA B (NFKB) IN RAT PINEAL GLAND

In mammals, the production of melatonin by the pineal gland is mainly controlled by the suprachiasmatic nuclei (SCN), the master clock of the circadian system. We have previously shown that agents involved in inflammatory responses, such as cytokines and corticosterone, modulate pineal melatonin synthesis. The nuclear transcription factor NFKB, detected by our group in the rat pineal gland, modulates this effect. Here, we evaluated a putative constitutive role for the pineal gland NFKB pathway. Male rats were kept under 12 h: 12 h light-dark (LD) cycle or under constant darkness (DD) condition. Nuclear NFKB was quantified by electrophoretic mobility shift assay on pineal glands obtained from animals killed throughout the day at different times. Nuclear content of NFKB presented a daily rhythm only in LD-entrained animals. During the light phase, the amount of NFKB increased continuously, and a sharp drop occurred when lights were turned off. Animals maintained in a constant light environment until ZT 18 showed diurnal levels of nuclear NFKB at ZT15 and ZT18. Propranolol (20 mg/kg, i.p., ZT 11) treatment, which inhibits nocturnal sympathetic input, impaired nocturnal decrease of NFKB only at ZT18. A similar effect was observed in free-running animals, which secreted less nocturnal melatonin. Because melatonin reduces constitutive NFKB activation in cultured pineal glands, we propose that this indolamine regulates this transcription factor pathway in the rat pineal gland, but not at the LD transition. The controversial results regarding the inhibition of pineal function by constant light or blocking sympathetic neurotransmission are discussed according to the hypothesis that the prompt effect of lights-off is not mediated by noradrenaline, which otherwise contributes to maintaining low levels of nuclear NFKB at night. In summary, we report here a novel transcription factor in the pineal gland, which exhibits a constitutive rhythm dependent on environmental photic information. (Author correspondence: rpmarkus@usp.br)

Sympathetic outflow activates the venom gland of the snake Bothrops jararaca by regulating the activation of transcription factors and the synthesis of venom gland proteins

The venom gland of viperid snakes has a central lumen where the venom produced by secretory cells is stored. When the venom is lost from the gland, the secretory cells are activated and new venom is produced. The production of new venom is triggered by the action of noradrenaline on both alpha(1)- and beta-adrenoceptors in the venom gland. In this study, we show that venom removal leads to the activation of transcription factors NF kappa B and AP-1 in the venom gland. In dispersed secretory cells, noradrenaline activated both NF kappa B and AP-1. Activation of NF kappa B and AP-1 depended on phospholipase C and protein kinase A. Activation of NF kappa B also depended on protein kinase C. Isoprenaline activated both NF kappa B and AP-1, and phenylephrine activated NF kappa B and later AP-1. We also show that the protein composition of the venom gland changes during the venom production cycle. Striking changes occurred 4 and 7 days after venom removal in female and male snakes, respectively. Reserpine blocks this change, and the administration of alpha(1)- and beta-adrenoceptor agonists to reserpine-treated snakes largely restores the protein composition of the venom gland. However, the protein composition of the venom from reserpinized snakes treated with alpha(1)- or beta-adrenoceptor agonists appears normal, judging from SDS-PAGE electrophoresis. A sexual dimorphism in activating transcription factors and activating venom gland was observed. Our data suggest that the release of noradrenaline after biting is necessary to activate the venom gland by regulating the activation of transcription factors and consequently regulating the synthesis of proteins in the venom gland for venom production.

Local Corticosterone Infusion Enhances Nocturnal Pineal Melatonin Production In Vivo

Melatonin, an important marker of the endogenous rhythmicity in mammals, also plays a role in the body defence against pathogens and injuries. In vitro experiments have shown that either pro- or anti-inflammatory agents, acting directly in the organ, are able to change noradrenaline-induced pineal indoleamine production. Whereas corticosterone potentiates melatonin production, incubation of the gland with tumour necrosis factor-alpha decreases pineal hormonal production. In the present study, we show that nocturnal melatonin production measured by intra-pineal microdialysis is enhanced in pineals perfused with corticosterone at concentrations similar to those measured in inflamed animals. In vitro experiments suggest that this enhancement may be due to an increase in the activity of the two enzymes that convert serotonin to N-acetylserotonin (NAS) and NAS to melatonin. The present results support the hypothesis that the pineal gland is a sensor of inflammation mediators and that it plays a central role in the control of the inflammatory response.

6-Sulfatoxymelatonin as a predictor of clinical outcome in depressive patients

Objectives This study established the value of the 6-sulfatoxymelatonin (aMT6s) urine concentration as a predictor of the therapeutic response to noradrenaline reuptake inhibitors in depressive patients. Methods Twenty-two women aged 18-60 years were selected. Depressive symptoms were assessed by using the Hamilton Depression Scale. Urine samples were collected at 0600-1200 h, 1200-1800 h, 1800-2400 h, and 2400-0600 h intervals, 1 day before and 1 day after starting on the nortriptyline treatment. Urine aMT6s concentration was analyzed by a one-way analysis of variance/Bonferroni test. Spearman`s rank correlation coefficient was used to analyze the correlation between depressive symptoms after 2 weeks of antidepressant treatment and the increase in aMT6s urine concentration. Results Higher and lower size effect groups were compared by independent Student`s t-tests. At baseline, the 2400- to 0600-h interval differed from all other intervals presenting a significantly higher aMT6s urine concentration. A significant difference in aMT6s urine concentrations was found 1 day after treatment in all four intervals. Higher size effect group had lower levels of depressive symptoms 2 weeks after the treatment. A positive correlation between depressive symptoms and the delta of aMT6s in the 2400-0600h interval was observed. Conclusion Our results reinforce the hypothesis that aMT6s excretion is a predictor of clinical outcome in depression, especially in regard to noradrenaline reuptake inhibitors. Copyright (C) 2011 John Wiley & Sons, Ltd.

A study of the catecholaminergic inputs to the dorsal premammillary nucleus

The dorsal premammillary nucleus (PMd) is one of the most responsive hypothalamic sites during exposure to a predator or its odor, and to a context previously associated with a predatory threat; and lesions or pharmacological inactivation centered therein severely reduced the anti-predatory defensive responses. Previous studies have shown that beta adrenergic transmission in the PMd seems critical to the expression of fear responses to predatory threats. In the present study, we have investigated the putative sources of catecholaminergic inputs to the PMd. To this end, we have first described the general pattern of catecholaminergic innervation of the PMd by examining the distribution and morphology of the tyrosine hydroxylase (TH) immunoreactive fibers in the nucleus; and next, combining Fluoro Gold (FG) tracing experiments and TH immunostaining, we determined the putative sources of catecholaminergic inputs to the nucleus. Our results revealed that the PMd presents a moderately dense plexus of catecholaminergic fibers that seems to encompass the rostral pole and ventral border of the nucleus. Combining the results of the FG tract-tracing and TH immunostaining, we observed that the locus coeruleus was the sole brain site that contained double FG and TH immunostained cells. In summary, the evidence suggests that the locus coeruleus is seemingly a part of the circuit responding to predatory threats, and, as shown by the present results, is the sole source of catecholaminergic inputs to the PMd, providing noradrenergic inputs to the nucleus, which, by acting via beta adrenoceptor, seems to be critical for the expression of anti-predatory responses. (C) 2011 Elsevier Ireland Ltd. All rights reserved.