It has been well established that the stress-related neurochemical systems corticotropin-releasing factor (CRF), noradrenaline (NA), and dopamine (DA) mediate stress-induced reinstatement of drug seeking. The three series of experiments presented in this dissertation constitute a further exploration of the role these neurochemical circuits play in reinstatement by providing the first direct exploration of whether central CRF and catecholamine (NA and DA) systems interact to influence reinstatement of cocaine seeking. The primary objective of the first series of experiments was to determine whether NA and CRF systems interact to mediate reinstatement of cocaine seeking and, if so, to determine the direction of this interaction. Results showed that central administration of NA induced reinstatement and up-regulated the expression of c-fos mRNA, a marker of neuronal activation, in brain regions involved in footshock-induced reinstatement. Pretreatment with a CRF antagonist blocked NA-induced reinstatement. In contrast, pretreatment with the α2-adrenoceptor agonist, clonidine, failed to block CRF-induced reinstatement. Taken together, these findings suggest a functional interaction between NA and CRF systems in mediating stress-induced reinstatement of cocaine seeking, whereby activation of CRF receptors occurs subsequent to, and downstream of, the sites of action of NA. A second series of experiments examined the role of D1- and D2-like receptors in CRF-induced reinstatement. Pretreatment with the D1- or D2-like receptor antagonists, SCH23390 and raclopride, respectively, dose-dependently blocked CRF-induced reinstatement of cocaine seeking. Taken together with previous findings, these results suggest that CRF-induced reinstatement of cocaine seeking likely involves DAergic signaling via D1- and D2-like receptors, subsequent to activation of CRF receptors. The final series of experiments investigated the neuropharmacology of yohimbine-induced reinstatement, focusing on the roles of α2-adrenoceptors, D1- and D2-like receptors. These experiments were prompted by an unexpected finding in the first series of experiments, in which a CRF antagonist failed to interfere in yohimbine-induced reinstatement of cocaine seeking. Results showed that pretreatment with the α2-adrenoceptor agonist, clonidine, or raclopride, prior to tests for yohimbine-induced reinstatement failed to influence responding. In contrast, pretreatment with SCH23390 blocked yohimbine-induced reinstatement. Taken together, these findings suggest that yohimbine may act through system(s) other than NA to have its effects.

The neuropeptide, corticotropin-releasing factor (CRF), plays a critical role in the central regulation of various stress-related behaviours, including those unique to subjects with prior cocaine experience. The three series of experiments presented in this dissertation explored the role of two neurochemical systems, the teneurin C-terminal associated peptides (TCAP) and the endocannabinoids (eCBs), in several cocaine- and anxiety-related behaviours induced or mediated by CRF. The first series of experiments examined the effects of TCAP-1 on the reinstatement of cocaine seeking and expression of cocaine-induced behavioural sensitization. Repeated (5-day), but not acute, TCAP-1 treatment blocked the reinstatement of cocaine seeking induced by central injections of CRF. TCAP-1 was, however, without effect on footshock- or cocaine-induced reinstatement. Repeated TCAP-1 further interfered with the expression of behavioural sensitization to a CRF, but not a cocaine, challenge. These findings suggest that TCAP-1 normalizes CRF signaling dysregulated by cocaine exposure to interfere in the subsequent effects of CRF on cocaine-related behaviours. A parallel series of experiments investigated the role of eCB signaling at CB1 receptors in the reinstatement of cocaine seeking and cocaine-sensitized locomotion. Pretreatment with the CB1 receptor antagonist, AM251, selectively interfered with CRF-, but not footshock- or cocaine-induced reinstatement. AM251 further blocked the expression of behavioural sensitization induced by challenge injections of both CRF and cocaine. These findings reveal a mediating role for CB1 receptor transmission in the effects of CRF on cocaine-related behaviours. A final series of experiments examined the role of CB1 receptor transmission in the behavioural anxiety induced by central injections of CRF, and by withdrawal from chronic cocaine exposure. AM251, although itself anxiogenic, reversed anxiety induced by CRF and cocaine withdrawal. Furthermore, AM251 elevated plasma corticosterone levels, indicative of increased HPA axis activity, irrespective of CRF treatment or cocaine withdrawal. These findings suggest that CRF- and cocaine withdrawal-induced anxiety are mediated, at least in part, by CB1 receptor transmission, independent of HPA axis regulation. The collective findings are discussed within a framework of CRF-TCAP-eCB interactions, wherein TCAP-1 and AM251 are proposed to act in parallel to modulate amygdalar CRF transmission, and thus regulate the expression of cocaine- and anxiety-related behaviours.

It has been well established that the stress-related neurochemical systems corticotropin-releasing factor (CRF), noradrenaline (NA), and dopamine (DA) mediate stress-induced reinstatement of drug seeking. The three series of experiments presented in this dissertation constitute a further exploration of the role these neurochemical circuits play in reinstatement by providing the first direct exploration of whether central CRF and catecholamine (NA and DA) systems interact to influence reinstatement of cocaine seeking. The primary objective of the first series of experiments was to determine whether NA and CRF systems interact to mediate reinstatement of cocaine seeking and, if so, to determine the direction of this interaction. Results showed that central administration of NA induced reinstatement and up-regulated the expression of c-fos mRNA, a marker of neuronal activation, in brain regions involved in footshock-induced reinstatement. Pretreatment with a CRF antagonist blocked NA-induced reinstatement. In contrast, pretreatment with the α2-adrenoceptor agonist, clonidine, failed to block CRF-induced reinstatement. Taken together, these findings suggest a functional interaction between NA and CRF systems in mediating stress-induced reinstatement of cocaine seeking, whereby activation of CRF receptors occurs subsequent to, and downstream of, the sites of action of NA. A second series of experiments examined the role of D1- and D2-like receptors in CRF-induced reinstatement. Pretreatment with the D1- or D2-like receptor antagonists, SCH23390 and raclopride, respectively, dose-dependently blocked CRF-induced reinstatement of cocaine seeking. Taken together with previous findings, these results suggest that CRF-induced reinstatement of cocaine seeking likely involves DAergic signaling via D1- and D2-like receptors, subsequent to activation of CRF receptors. The final series of experiments investigated the neuropharmacology of yohimbine-induced reinstatement, focusing on the roles of α2-adrenoceptors, D1- and D2-like receptors. These experiments were prompted by an unexpected finding in the first series of experiments, in which a CRF antagonist failed to interfere in yohimbine-induced reinstatement of cocaine seeking. Results showed that pretreatment with the α2-adrenoceptor agonist, clonidine, or raclopride, prior to tests for yohimbine-induced reinstatement failed to influence responding. In contrast, pretreatment with SCH23390 blocked yohimbine-induced reinstatement. Taken together, these findings suggest that yohimbine may act through system(s) other than NA to have its effects.

The involvement of corticotropin-releasing hormone (CRH) and neuropeptide Y (NPY) in the pathophysiology of anxiety and anxiety-related disorders is well established. The objective of this study is to explore the genetic variations in the CRH and NPY genes in a well-documented behavioral animal model, the vervet monkey (Chlorocebus aethiops sabaeus), in order to uncover a possible association between these polymorphisms and behavioral traits quantitatively extracted following analysis of social behavior and responses to novelty challenges. / The vervet CRH and NPY genes were amplified and sequenced; the priority was given to the regions expanding from -1kb upstream of the transcription initiation site (where most of the regulatory elements are found in both genes) through the second exon. / Polymorphism discovery analysis revealed the presence of 9 vervet CRH SNPs and 9 vervet NPY SNPs; the SNPs are relatively evenly distributed across the regions covered. An association between one intronic NPY SNP and "defensive aggression" was detected. / These results are coherent with other reports implicating NPY in defensive aggressive behavior, and support the notion that fear responses are fundamental behavioral traits for the dissection of anxiety.

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 80-97).

Thesis (Ph.D. (Psychiatry))--University of Pretoria, 2003. / Summary in English and Afrikaans. Includes bibliographical references.

H ιδιοπαθής θρομβοπενική πορφύρα είναι ένα αυτοάνοσο νόσημα που χαρακτηρίζεται από χαμηλό αριθμό αιμοπεταλίων και αιμορραγίες. Επιπλέον αυτή η ασθένεια κατηγοριοποιείται σε οξεία (όταν διαρκεί λιγότερο από έξι μήνες) και χρόνια μορφή. Η λεπτίνη είναι μια ορμόνη/κυτταροκίνη που παράγεται από τα αδιποκύτταρα και ρυθμίζει την όρεξη και τον μεταβολισμό. Ως κυτταροκίνη η λεπτίνη προάγει την Th1 απόκριση και παίζει πολύ σημαντικό ρόλο στα αυτοάνοσα νοσήματα όπως έχει παρατηρηθεί σε πολλά μοντέλα ζώων. Στην εργασία αυτή μελετήσαμε τον ρόλο της λεπτίνης στην παιδική ιδιοπαθή θρομβοπενική πορφύρα (ΙΘΠ). Από τα πειράματά μας διαπιστώσαμε ότι τα επίπεδα της λεπτίνης συσχετίζονται αρνητικά με τον αριθμό των αιμοπεταλίων των ασθενών. Επιπλέον αποδείξαμε ότι στην ασθένεια που μελετήσαμε η λεπτίνη έχει αντί-φλεγμονώδη ρόλο αφού επάγει την έκφραση της IL-10 από το μονοκύτταρα Το μόριο της εκλυτικής ορμόνης της κορτικοτροπίνης (CRH) εκφράζεται κυρίως στον υποθάλαμο και ενεργοποιεί μέσω του άξονα υποθάλαμος-υπόφυση-επινεφρίδια τα γλυκοκορτικοειδή τα οποία έχουν ανοσοκατασταλτική δράση. Η CRH που εντοπίζεται στην περιφέρεια έχει αντιθέτως προ-φλεγμονώδη δράση. Εμείς μετρήσαμε τα επίπεδα της CRH στο πλάσμα υγιώς και ασθενών δοτών και παρατηρήσαμε ότι στους υγιείς δότες η CRH έχει την ικανότητα να ρυθμίζει αρνητικά την έκφραση της λεπτίνης. Ο έλεγχος όμως αυτός χάνεται στους ασθενείς με αποτέλεσμα τα επίπεδα τα λεπτίνης αυξάνονται στον ορό τους / Ιdiopathic thrombocytopenic purpura is an autoimmune disease characterized by a low platelet count and bleeding. Moreover this disorder is classified as acute (of six month or less duration) or chronic. Leptin is an adipocyte-derived hormone/cytokine that regulates food intake and basal metabolism. As a cytokine leptin promotes T helper 1 (TH1)-cell differentiation and can modulate the onset and progression of autoimmune responses in several animal models of disease. Here, we review the role of leptin in childhood idiopathic thrombopenic purpura (ITP). We found that leptin levels negatively correlated with platelet numbersand also that it plays an active anti-inflammatory role by promoting IL-10 secretion by monocytes. Corticotropin-Releasing Hormone (CRH) CRH, the hypothalamic component of the hypothalamic-pituitary,adrenal axis, attenuates inflammation through stimulation of glucocorticoid release, whereas peripherally expressed CRH acts as a proinflammatory mediator. We measured CRH levels in the plasma of children suffering from ITP and in the plasma of the paediatric controls, and we found that in controls CRH down-regulates leptin’s expression but not in patients.