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Selective 5-HT reuptake inhibitor antidepressants (SSRIs) are the first choice in major depressive disorder (MDD), but 50% of affected patients do not show improvement. Galanin(1-15) [GAL(1-15)] enhanced Fluoxetine antidepressant-like effects in an animal model of depression, the olfactory bulbectomy (OBX), however, further detailed analysis of GAL(1-15) effects as augmentation treatment in OBX rats are needed. In OBX rats, we analysed the effect of GAL(1–15) on Escitalopram (ESC)-mediated responses in behavioural tests related to despair. We studied whether GAL(1–15) effects involved 5-HT1AR using an in vivo model siRNA 5-HT1A knockdown rats. Moreover, we analysed by immunohistochemistry the expression of the immediate-early gene c-Fos (c-Fos IR) after the administration of GAL(1-15)+ESC in OBX rats in several nuclei involved in MDD. GAL(1-15) enhances the antidepressant-like effects of ESC, and the GALR2 antagonist M871 blocked GAL(1-15) mediated actions. The downregulation of 5-HT1AR by siRNA was sufficient to block GAL(1-15) effects. Our immunohistochemistry and principal component analysis (PCA) analysis suggest that two functional networks are involved in these effects, one includes the lateral (LHb) and medial (mHb) habenula, dorsal raphe (DR) and ventral tegmental area (VTA), and the other consists of the dentate gyrus (DG), and prefrontal cortex (PFC). The results open up the possibility of using GAL(1-15) in combination with SSRIs as a novel strategy for treating MDD.

Alcohol consumption is considered a major risk factor for disease and mortality worldwide. In the absence of effective treatments in alcohol use disorders, it is important to find new biological targets that could modulate alcohol consumption. We tested the role of the N-terminal galanin fragment (1-15) [GAL(1-15)] in voluntary ethanol consumption in rats using the two-bottle choice paradigm as well as compare the effects of GAL(1-15) with the whole molecule of GAL. We describe for the first time that GAL(1-15), via central mechanisms, induces a strong reduction in preference and ethanol consumption in rats. These effects were significantly different than GAL. GAL receptor (GALR) 2 was involved in these effects, because the specific GALR2 antagonist M871 blocked GAL(1-15) mediated actions in preference and ethanol intake. Importantly, the mechanism of this action involves changes in GALR expression and also in immediate-early gene C-Fos and receptors-internalization-related gene Rab5 in the striatum. The relevance of the striatum as a target for GAL(1-15) was supported by the effect of GAL(1-15) on the locomotor activity of rats after ethanol administration. These results may give the basis for the development of novel therapeutics strategies using GAL(1-15) analogues for the treatment of alcohol use disorders in humans.

Insulin-like growth factor-II (IGF-II) is a naturally occurring hormone that exerts neurotrophic and neuroprotective properties in a wide range of neurodegenerative diseases and ageing. Accumulating evidence suggests that the effects of IGF-II in the brain may be explained by its binding to the specific transmembrane receptor, IGFII/M6P receptor (IGF-IIR). However, relatively little is known regarding the role of IGF-II through IGF-IIR in neuroprotection. Here, using adult cortical neuronal cultures, we investigated whether IGF-II exhibits long-term antioxidant effects and neuroprotection at the synaptic level after oxidative damage induced by high and transient levels of corticosterone (CORT). Furthermore, the involvement of the IGF-IIR was also studied to elucidate its role in the neuroprotective actions of IGF-II. We found that neurons treated with IGF-II after CORT incubation showed reduced oxidative stress damage and recovered antioxidant status (normalized total antioxidant status, lipid hydroperoxides and NAD(P) H:quinone oxidoreductase activity). Similar results were obtained when mitochondria function was analysed (cytochrome c oxidase activity, mitochondrial membrane potential and subcellular mitochondrial distribution). Furthermore, neuronal impairment and degeneration were also assessed (synaptophysin and PSD-95 expression, presynaptic function and FluoroJade B® stain). IGF-II was also able to recover the long-lasting neuronal cell damage. Finally, the effects of IGF-II were not blocked by an IGF-IR antagonist, suggesting the involvement of IGF-IIR. Altogether these results suggest that, in or model, IGF-II through IGF-IIR is able to revert the oxidative damage induced by CORT. In accordance with the neuroprotective role of the IGF-II/IGF-IIR reported in our study, pharmacotherapy approaches targeting this pathway may be useful for the treatment of diseases associated with cognitive deficits (i.e., neurodegenerative disorders, depression, etc.)., Graphical abstract fx1, Highlights • First evidence that IGF-II reverts oxidative synaptic damage produced by corticoids. • IGF-II recovers mitochondrial function in synapses after oxidative damage. • IGF-II restores mitochondrial distribution in neurons after oxidative damage. • Evidence of the involvement of IGF-II receptor in the recovery of synaptic function. • IGF-II reverts neurodegeneration induced by oxidative damage produced by corticoids.

Galanin (1-15) [GAL(1–15)] participates in mood regulation and depression. GAL(1–15) is also able to enhance the antidepressant effects induced by Fluoxetine (FLX) in the forced swimming test through interaction between GALR1-GALR2 and 5-HT1A receptors that induced changes in the binding characteristics and mRNA of the 5-HT1AR in the hippocampus. Since the medial prefrontal cortex (mPFC) is a core region for the interaction between emotional processing and cognition with a high density of 5-HT1AR and GALR1 and GALR2, we have analyzed the binding characteristics and mRNA levels of 5-HT1AR in the mPFC after GAL(1–15)-FLX administration in the rats. GAL(1–15) increased the Kd and the Bmax of the 5HT1AR agonist binding in the mPFC as well as the mRNA levels of 5-HT1AR in mPFC. Moreover, GAL(1–15) reversed the effects of memory impairment induced by FLX(10 mg/kg) in the Novel Object Recognition task. GALR2 was involved in these effects, since the specific GALR2 antagonist M871 blocked GAL(1–15) mediated actions at behavioral level. On the contrary GAL(1–15) did not reverse the effect of FLX in the Object Location Memory task. In conclusion, our results describe an interactions between GAL(1–15) and FLX in the mPFC involving interactions at the 5-HT1AR receptor level in the plasma membrane with changes at the transcriptional level with implications also at functional level. The GALR1-GALR2-5-HT1A heteroreceptor could be postulated to be used to reverse some of the adverse effects of FLX on memory processes.

Galanin is a 29 amino acid neuropeptide widely distributed in neurons within the central nervous system. Galanin exerts its biological activities through three different G protein-receptors and participates in a number of functions, including mood regulation. Not only Galanin but also Galanin N-terminal fragments like Galanin(1-15) are active at the central level. In this work, we review the latest findings in studies on Galanin and Galanin(1-15) in depression-related behaviours. Our focus is on animal models for depression, and we pay some attention to research data obtained in human studies. Since Serotonin (5-HT), especially through 5-HT1A, and Galanin receptors interact at both pre-and postsynaptic level, the development of drugs targeting potential GAL1-GAL2-5-HT1A heteroreceptor complexes linked to the raphe-hippocampal 5-HT neurons may represent new treatment strategies in depression.

Junta de Andalucia CVI6476.Universidad de Malaga. Campus de Excelencia Internacional Andalucia Tech.

Ponencia Invitada Galanin (GAL) is involved in several functions including mood regulation. The GAL N-terminal fragment (1-15) [GAL(1-15)] also participates at central level and a differential role of GAL(1-15) compared with GAL has been proposed. In this work we have analysed if GAL(1-15) contributes to depression- and anxiety -related behaviours using the forced swimming test, tail suspension test, open field and light/dark test. We tested the involvement of the GAL receptor 2 (GALR2) in GAL(1-15) effects with the GAL receptor antagonist M871 and with an in vivo model of siRNA GALR2 knockdown rats. The proximity of GALR1 and GALR1 was also examined with the proximity ligation assay (PLA). GAL(1-15) induced strong depression-like and anxiogenic-like effects in all the tests. The involvement of the GALR2 was demonstrated with M871 and with the siRNA GALR2 knockdown rats. The PLA indicated the existence of GALR1-GALR2 heteroreceptor complexes in the dorsal hippocampus and especially in the dorsal raphe nucleus. Our results indicate that GAL(1-15) exerts strong depression-related and anxiogenic-like effects and may give the basis for the development of drugs targeting GALR1-GALR2 heteroreceptor complexes in the raphe-limbic system for the treatment of depression and anxiety. This study was supported by Junta de Andalucía CVI6476. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

The interactions between neuropeptide Y (NPY), specifically through NPY Y1 and Y2 receptor subtypes and the Galanin N-terminal fragment (1-15) [GAL(1-15)] were analyzed at the cardiovascular level. The cardiovascular effects of intracisternal coinjections of GAL(1-15) and NPY, NPY Y1 or Y2 agonist have been investigated as well as quantitative receptor autoradiography of the binding characteristics of NPY Y1 and Y2 receptor subtypes in the nucleus of the solitary tract (NTS) in the presence or absence of GAL(1-15). The coinjection of NPY with GAL(1-15) induces a significant vasopressor action. The coinjection of the NPY Y2 agonist and GAL(1-15) induced a similar increase of mean arterial pressure as induced by NPY+GAL(1-15), actions that were not observed with the NPY Y1 agonist+GAL(1-29). No interactions were observed at heart rate level. GAL(1-15) 3 nM significantly and substantially increased NPY-Y2 agonist binding in the NTS by about 50%. This effect was significantly blocked (p0.01) in the presence of the specific Galanin antagonist M40. The NPY-Y1 agonist binding was not modified in the presence of GAL(1-15). The present findings suggest the existence of a facilitatory effect of GAL(1-15) mediated via Galanin receptors on the NPY Y2 receptor subtype and its cardiovascular function within the NTS.

Galanin N-terminal fragment (1-15) [GAL(1-15)] is associated with depression-related and anxiogenic-like effects in rats. In this study, we analyzed the ability of GAL(1-15) to modulate 5-HT1A receptors (5-HT1AR), a key receptor in depression. GAL(1-15) enhanced the antidepressant effects induced by the 5-HT1AR agonist 8-OH-DPAT in the forced swimming test. These effects were stronger than the ones induced by Galanin (GAL). This action involved interactions at receptor level since GAL(1-15) affected the binding characteristics and the mRNA levels of 5-HT1AR in the dorsal hippocampus and dorsal raphe. The involvement of the GALR2 was demonstrated with the GALR2 antagonist M871. Proximity ligation assay experiments indicated that 5-HT1AR are in close proximity with GALR1 and GALR2 in both regions and in raphe RN33B cells. The current results indicate that GAL(1-15) enhances the antidepressant effects induced by 8-OH-DPAT acting on 5-HT1AR operating as postjunctional or as autoreceptors. These results may give the basis for the development of drugs targeting potential GALR1-GALR2-5-HT1AR heteroreceptor complexes linked to the raphe-hippocampal 5-HT neurons for the treatment of depression.

Background: Galanin (GAL) plays a role in mood regulation. In this study we analyzed the action of the active N-terminal fragment [GAL(1–15)] in anxiety- and depression-related behavioral tests in rats. Methods: The effect of GAL(1–15) was analyzed in the forced swimming test, tail suspension test, open field test, and light/dark test. The proximity of GAL1 and GAL2 receptors was examined with the proximity ligation assay (PLA). We tested the GAL receptors involved in GAL(1–15) effects with the GAL2 receptor antagonist M871 and with an in vivo model of siRNA GAL2 receptor knockdown or siRNA GAL1 receptor knockdown rats. The effects of GAL(1–15) were also studied in the cell line RN33B. Results: GAL(1–15) induced strong depression-like and anxiogenic-like effects in all the tests. These effects were stronger than the ones induced by GAL. The involvement of the GAL2 receptor was demonstrated with M871 and with the siRNA GAL2 receptor knockdown rats. The PLA indicated the possible existence of GAL1 and GAL2 heteroreceptor complexes in the dorsal hippocampus and especially in the dorsal raphe nucleus. In the siRNA GAL1 receptor knockdown rats the behavioral actions of GAL(1–15) disappeared, and in the siRNA GAL2 receptor knockdown rats the reductions of the behavioral actions of GAL(1–15) was linked to a disappearance of PLA. In the cell line RN33B, GAL(1–15) decreased 5-HT immunoreactivity more strongly than GAL. Conclusions: Our results indicate that GAL(1–15) exerts strong depression-related and anxiogenic-like effects and may give the basis for the development of drugs targeting GAL1 and GAL2 heteroreceptor complexes in the raphe-limbic system for the treatment of depression and anxiety.

Galanin (GAL) and neuropeptide Y (NPY) are neuropeptides involved in behaviors associated with anxiety. Both neuropeptides interact in several central functions. However, the potential behavioral and cellular interactions between them in anxiety are unknown. GAL was found to act through GAL receptor 2 (GALR2) to enhance NPYY1 receptor (NPYY1R)-mediated anxiolytic behaviors in rats. Using receptor autoradiography, c-Fos expression and in situ proximity ligation assay, the medial paracapsular intercalated nuclei of the amygdala were determined to be a key area in the interaction probably involving the formation of GALR2/NPYY1R heteroreceptor complexes. In cell cultures costimulation of GALR2 and NPYY1R induced changes in the functions of these receptors. The changes involved a potentiation of the decrease in the phosphorylation of CREB induced by NPYY1R and a delay in the internalization of NPYY1R. These results indicate that GALR2/NPYY1R interactions can provide a novel integrative amygdaloid mechanism in anxiety.

The aim of this study was to evaluate by quantitative receptor autoradiography the interactions between Neuropeptide Y Y1 (NPY Y1) and Galanin (GAL) receptors in the dorsal raphe nucleus (DRN) where both GAL receptors and NPY Y1 receptors exist. The ability of the GAL receptor antagonist M35 to block the GAL action was also evaluated. Double immunocytochemical staining of 5-hydroxytryptmine and c-Fos and stereology techniques were used to study the specific cell activation in the DRN after the intracerebroventricular coinjections of GAL and the NPY Y1/Y5 agonist [ 125 I] Leu 31 ,Pro 34 PYY. GAL (0.3 nM) decreases [ 125 I] Leu 31 ,Pro 34 PYY binding in the DRN by 48% (p < 0.01) as shown by quantitative receptor autoradiography. This effect was reversed with the GAL receptor antagonist M35. Intracerebroventricular coinjections of NPY Y1/Y5 agonist and GAL reduced the c-Fos expression in the serotoninergic cells induced by the NPY Y1/Y5 agonist in DRN. These results indicate the existence of antagonistic interactions between GAL receptors and NPY Y1 receptors in the DRN that may be of relevance in mood disorders.

groups. GAL and Y1 agonist alone did not change any of the parameters analyzed. However in the open field test the coadministration of GAL and Y1 agonist significantly increased the number of entries (p

The presence of Galanin and Neuropeptide Y and/or their receptors in several areas of the brain involved in memory, mood, cardiovascular control and food intake indicates that Galanin, and Neuropeptide Y could equilibrate the physiological actions of each other. There is evidence for the existence of interactions between Galanin Receptor and Neuropeptide Y Receptor in the nucleus of the solitarii tract (NTS), hypothalamus and dorsal raphe nucleus probably taking place with the formation of heteromers between Galanin Receptor and Neuropeptide Y Y1 Receptor. The galanin fragment (Gal 1-15) preferring receptors may instead be formed by the GalR1-GalR2 heteromer which in the NTS may interact with Neuropeptide Y Y2 receptors. These receptor heteromers may be one key molecular mechanism for Galanin and its N-terminal fragment (Galanin 1-15) to modulate the function of different types of glia-neuronal networks in the CNS, especially the emotional, metabolic and cardiovascular networks.