No description available.

No description available.

No description available.

Oxytocin has established roles in parturition and lactation, but can also be released in response to non-reproductive stimuli, such as hyperosmolarity and stress. As a majority of appetite regulating peptides activate the hypothalamo-pituitary-adrenal stress axis, and oxytocin is also a stress hormone in the rat, it was hypothesized that the oxytocin system in the neurohypophysial axis could be a target for appetite-regulating peptides of central and peripheral origin. The effects of central administration of neuropeptide Y (NPY; a central orexigenic peptide and a central and peripheral neurotransmitter co-released with noradrenaline; n=5 rats) and systemic administration of secretin (a peripheral gut peptide belonging to the family of brain-gut peptides; n=26) and leptin (a peripheral anorexigenic peptide from adipose tissue; n=23) on the electrical activity of SON oxytocin neurones in vivo were studied in urethane-anaesthetized female rats with extracellular recording. Effects were compared with the excitatory responses to cholecystokinin (CCK; a peripheral anorexigenic gut peptide; n=45). Influences of fasting and pregnancy and effects of these peptides on the activity of SON vasopressin neurones were also studied. Results: (1) All the central and peripheral appetite peptides tested increased the electrical activity of SON oxytocin neurones. (a) NPY: Basal firing rate of 3.5 ± 1.05 (mean ± s.e.m) spikes/s was increased by 1 ± 0.45 spikes/s 1min after NPY (basal vs 0-10min post-NPY: P=0.03, paired t-test; n=5). (b) Secretin: Basal rate of 4.1 ± 0.4 spikes/s was increased by 1.7 ± 0.2 spikes/s 2.5min after secretin (basal vs 0-10min post-secretin: P<0.001, paired t-test; n=26). (c) Leptin: Basal rate of 3.4 ± 0.4 spikes/s was increased by 0.4 ± 0.08 spikes/s 1.5min after leptin (basal vs 0-10min post-leptin: P=0.01, paired t-test; n=23). (d) CCK: Basal rate of 3.6 ± 0.3 spikes/s was increased by 1.1 ± 0.15 spikes/s 1min after CCK (basal vs 0-10min post- CCK: P<0.001, Wilcoxon signed rank test; n=45). (2) Secretin induced excitatory responses were greater than to other peptides (P<0.001, Kruskal-Wallis one-way ANOVA on ranks). (3) Secretin dose-dependently increased SON oxytocin neurone electrical activity and peripheral oxytocin release in anaesthetized rats. (4) Intracerebroventricular infusion and microdialysis studies with benoxathian (α1 adrenergic antagonist) revealed that secretininduced excitation of SON oxytocin and vasopressin neurones involves central excitatory noradrenergic pathways. (5) Fasting for 18h did not alter the excitation of SON oxytocin neurones induced by secretin, CCK and leptin. (6) The pathway leading to excitation of oxytocin neurones by CCK was not influenced by prior leptin administration. (7) SON oxytocin neurones were responsive to leptin during late pregnancy. (8) NPY-induced excitation of oxytocin neurones was intact in anaesthetised late pregnant rats, contrasting with attenuated oxytocin secretory responses observed previously in conscious rats. (9) Systemic NPY excited SON oxytocin neurones. (10) Systemic CCK administration either inhibited (77%) or did not affect (23%) SON vasopressin neurones, while leptin had no significant effect, and responses to secretin were predominantly excitatory (67%). Systemic NPY inhibited vasopressin neurones, but central NPY was ineffective. Conclusion: Appetite peptides target SON oxytocin neurones. Postprandially released secretin and leptin might, like CCK, induce peripheral oxytocin release, so as to regulate water and electrolyte homeostasis, which is inevitably disturbed during feeding. Any central release of oxytocin induced by these peptides, might regulate feeding behaviour and satiety. Oxytocin neurone excitation induced by NPY may be relevant during stress responses.

The aim of this study was to investigate in vitro transdermal diffusion of a small peptide namely arginine vasopressin (AVP) with the aid of the novel PheroidTM drug delivery system. Generally, peptides seem unfit for transdermal permeation, but it was thought prudent to explore the suitability of this lipid-based system after success was achieved with entrapment of tuberculostatics, bacteria and viruses. Bestatin (a selective aminopeptidase inhibitor) was employed to circumvent any skin-related degradation of the active. Therefore, the effect of bestatin on the preservation of AVP during diffusion was investigated. Vertical Franz cell diffusion studies were conducted with female abdominal skin, with AVP at a concentration of 150 pglml in the donor phase and Hepes buffer as the receptor phase over a twelve-hour period. To prove entrapment of AVP within the lipid structures of the PheroidsTM, fluorescentlylabelled samples were monitored by means of confocal laser scanning microscopy (CLSM), which revealed definite entrapment. In vitro permeation profiles for AVP exhibited a biphasic character, with the majority of permeation occurring during the first two hours. The PheroidTM delivery system proved to be advantageous when applied as delivery medium. The inclusion of bestatin has an enhancing effect on permeation probably due to its protection of AVP. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Magnocellular neurones (MCNs) are capable of secreting vasopressin and oxytocin from the somato-dendritic compartment, which can occur independently to secretion from nerve terminals. One hypothesis of the mechanism that regulates this differential release is that dendrites utilise different vesicle pools compared to those found in terminals. Little is known for the function of neuronal dendrites, especially the mechanism for peptide release. One theory is that vesicles stored in dendrites are non-released vesicles ready for recycling or degradation. Immunofluorescent labelling was performed on hypothalamic slices of the transgenic rat where enhanced green fluorescent protein (eGFP) was tagged to vasopressin. Lysosomes were detected by the lysosome-associated membrane protein LAMP1. Correlation analysis of LAMP1 labelling and VP-eGFP had shown that localisation of lysosomes in dendrites is positively correlated to loci of high vasopressin expression. This suggests active degradation of vesicles in dendrites. It is not known whether preferential release of peptides occurs along the profile of dendrites. Experiments were carried out using a temperature block to block exit of vesicles from the Golgi apparatus. Release of the temperature block triggered release of a wave of newly synthesised vesicles from the Golgi apparatus. Measurement of the fluorescent intensity of VP-eGFP showed that preferential release of peptides does not occur along the profile of dendrites. I have also utilised confocal live cell imaging to study the dynamics of dendritic vasopressin release using VP-eGFP slice explants. Experiments using high potassium stimulation showed significant increase in the release of vasopressin after priming with thapsigargin (intracellular calcium mobiliser), in accordance to in vitro release and microdialysis studies. These results demonstrate that live cell imaging can be achieved in magnocellular neurons, providing a robust model system in the study of dendritic peptide release. Large dense core vesicles (LDCVs) in other cell types such as bovine adrenal chromaffin cells were shown to segregate according to vesicle age, suggesting that vesicle age is an important factor in the regulation of peptide release. Whether vesicles of different age groups exist in magnocellular dendrites is not known. Thus, biolistic transfection with exogenous fluorescent proteins for expression under temporal control was carried out. However, low transfection rate in magnocellular neurones and the high background fluorescence caused by scattered gold particles used as bullets for transfection deemed this method inappropriate for the purpose of imaging vesicles. Hence, development of an adenoviral transduction system was employed. By using an inducible adenovirus gene construct coupled with a fluorescent reporter gene, it is possible to visualise vesicle pool segregation under different experimental conditions. Subcloning of a red fluorescent construct tagged to ppANF was tested on PC12 cells to show targeting of fluorescence expression to LDCVs. Successful production of an inducible adenoviral DNA with the red fluorescent construct insert was confirmed by PCR and DNA sequencing. Whilst the generation of viral particles is still to be achieved, successful production of the virus will be an invaluable system for inducible gene expression in neurones.

AVPR1A und NOS1 spielen in der aktuellen Forschung zu Paarbindungsverhalten bzw. Impulsivität eine wichtige Rolle. Ziel dieser Arbeit war es, einen Zusammenhang zwischen genetischen Varianten in diesen beiden Genen mit sexueller Aktivität, Treue und impulsivem Verhalten zu untersuchen. Dabei wurde die Hypothese aufgestellt, dass das lange Allel des AVPR1A RS3 Polymorphismus mit gesteigertem sexuellem Verhalten und entsprechend verringerter Treue assoziiert ist. Des Weiteren wurde postuliert, dass das kurze Allel von NOS1 ex1f-VNTR indirekt über gesteigerte Impulsivität und Extraversion mit Untreue und gesteigertem sexuellem Verhalten assoziiert ist. In Hinblick auf den NOS1 Polymorphismus konnte die Hypothese teilweise bestätigt werden. So zeigten Probanden, welche homozygot für das kurze Allel des NOS1 ex1f-VNTR waren, signifikant höhere Werte für Impulsivität und Extraversion, wohingegen Teilnehmer mit mindestens einem langen Allel signifikant höhere Werte für Gehemmtheit aufwiesen. Eine Assoziation zwischen gesteigerter Sexualität bzw. Untreue und diesen Varianten zeigte sich jedoch nicht. Allerdings zeigte sich auch auf der rein psychometrischen Ebene kein Zusammenhang zwischen gesteigerter Impulsivität und Untreue, so dass zusammenfassend zwar der direkte vermutete Assoziationsbefund repliziert werden konnte, die indirekte Annahme jedoch zu verwerfen ist. Auch für die beiden Polymorphismen RS1 und RS3 des Vasopressin-Rezeptor-Gens AVPR1A zeigten sich signifikante Ergebnisse. So konnte gezeigt werden, dass Probanden, welche homozygot für das lange Allel von RS3 sind, signifikant höhere Werte für Leistungsorientiertheit, Extraversion und Selbstbewusstsein, aber auch für Untreue und gesteigertes Sexualverhalten aufweisen. Für RS1 hingegen ergab sich lediglich, dass Probanden, welche homozygot für das lange Allel sind, impulsiver zu sein scheinen, während Probanden mit mindestens einem kurzen Allel eine Tendenz zu gesteigertem sexuellem Verhalten erkennen ließen. Zusammenfassend kann man daher sagen, dass die Hypothesen teilweise bestätigt werden konnten – unter den Einschränkungen dass die Stichprobengröße relativ gering war und alle Signifikanzwerte für multiples Testen unkorrigiert sind – und als Grundlage für weiterführende Studien hinsichtlich AVPR1A und NOS1 in Bezug auf menschliches Verhalten dienen können. / AVPR1A and NOS1 play an important role in recent research concerning pair bonding behaviour and impulsivity. We aimed at showing a connection between genetic variants of these two genes and sexual activity, constancy and impulsivity. We claimed that the long allele of AVPR1A RS3 polymorphism is associated with sexual activity and less constancy. We also claimed that the short allele of NOS1 ex1f-VNTR is associated with impulsivity and extraversion and consecutively also with sexual activity. Concerning the NOS1 polymorphism, our hypothesis could be proofed. Homozygous participants for the short allele of NOS1 ex1f-VNTR showed significant higher scores for impulsivity and extraversion, whereas participants with at least one long allele scored significant higher for inhibitness. Unfortunately there was no association between increased sexuality and these behaviours. On the psychometric level there also was no connection between impulsivity and infidelity. All together we must say that we could only replicate the direct association, whereas the indirect hypothesis could not be proofed. There also were significant results for both polymorphisms RS1 and RS3 of the vasopressin receptor gene AVPR1A. Homozygote participants for the long allele of RS3 scored significant higher on achievement-orientation, extraversion and self-confidence, but also for infidelity and sexuality. Concerning RS1, homozygote participants for the long allele scored higher on impulsivity, whereas participants with at least one short allele seem to be sexually more active. In summary one can say, that all hypotheses could be proofed, at least partly- knowing the limitation that the sample was quite small and all significances for multiple testing were uncorrected - and can be used as a basis for further studies concerning AVPR1A and NOS1 and their influence on human behaviour.

Thesis advisor: Alexa Veenema / Thesis advisor: Nicholas Worley / Oxytocin (OT) and vasopressin (AVP) often regulate social behaviors in sex-specific ways. We hypothesized that this could be mediated by sex differences in the OT receptor (OTR) and AVP V1a receptor (V1aR) in the brain. Here, we determined whether there are sex differences in OTR and V1aR binding densities in nodes of the social behavior neural network in the mouse brain. We also compared sex differences int he OTR and V1aR in the mouse brain with those found previously in the rat brain. Although mice and rats are closely related species, they also display differences in social behavior. Therefore, we predicted to find similar as well as unique sex differences in OTR and V1aR in mice compared to rats. Generally, we found that sex differences in OTR and V1aR binding densities are region-specific and species-specific. In detail, male mice showed higher OTR binding density than female mice in the medial amygdala, anterior lateral septum, and posterior bed nucleus of the stria terminalis. This is consistent with findings in rats. Furthermore, female mice displayed higher OTR binding density in the anteroventral periventricular nucleus and ventromedial hypothalamus. This is in contrast to rats, where males showed higher OTR binding densities in these regions. Lastly, females showed higher V1aR binding density in the anterior bed nucleus of the stria terminalis. However, this sex difference was not measured in rats due to low receptor expression in this region. Overall, these findings demonstrate the importance to determine sex differences in OTR and V1aR across species to gain a better understanding of the sex-specific behavioral functions of the OT and AVP systems. / Thesis (BS) — Boston College, 2017. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Biology.

Thesis advisor: Alexa H. Veemena / Across species, the juvenile period is characterized by increased social interaction with peers and heightened novelty-seeking behavior, as compared to any other life stage. These behaviors are likely to be highly adaptive during this developmental phase. Still, an excessive novelty-seeking phenotype may predispose individuals to risk-taking and substance abuse, while too little social engagement and low novelty-seeking are characteristics of neuropsychiatry disorders such as autism. The over-arching aim of this dissertation research has been to elucidate the neural mechanisms underlying juvenile social novelty-seeking behavior. Central activation of oxytocin, vasopressin V1a, and µ-opioid receptors (OTR, V1aR, and MOR, respectively) have been implicated in the regulation of adult social behavior, but our understanding of the expression and function of OTR, V1aR, and MORs in the juvenile brain is incomplete. Therefore, in Studies 1 and 2, age differences in binding density of OTR, V1aR, and MOR throughout the rat brain were identified using receptor autoradiography. Next, in Study 3, I established the social novelty preference test, a new paradigm designed to assess the preference of juvenile rats to interact with either a novel or a familiar (cage mate) conspecific. Using this social novelty preference test, in Studies 3, 4, and 5, the functional involvement of OTR, V1aR, and MOR in the regulation of juvenile social novelty preference was characterized using both intracerebroventricular and local in-vivo pharmacological manipulations. The results of these experiments demonstrate that both OTR and MOR activation in the brain are involved in the regulation of juvenile social novelty preference, particularly acting within the nucleus accumbens. Finally, in Study 5, I investigated the impact of social isolation on juvenile social novelty preference. My findings show that social isolation potently reduces social novelty preference, which, in turn, can be restored by MOR activation in the nucleus accumbens. Taken together, this body of work significantly advances our understanding of the neural systems underlying juvenile social novelty preference, and suggests that both oxytocin and opioid systems in the brain may be potential clinical targets for restoring social novelty-seeking behavior in neurodevelopmental disorders, such as autism.

A homeostase hidro-eletrolítica é controlada por informações sobre volume e a concentração dos íons dos líquidos corporais. Alterações da osmolalidade são detectadas por receptores presentes em diversas regiões do SNC, entre as quais os órgãos circunventriculares. Alterações conformacionais nestas células ativam neurônios localizados nos núcleos paraventricular (PVN) e supra-óptico (SON) do hipotálamo, que secretam ocitocina (OT) e vasopressina (AVP). A osmolalidade plasmática aumenta em conseqüência da alimentação, o que induz a secreção de OT e AVP. Os esteróides ovarianos podem influenciar o balanço de líquidos, modulando sistemas hormonais que regulam tanto o consumo quanto a excreção de água, ou agindo diretamente em neurônios ocitocinérgicos e vasopressinérgicos do hipotálamo. No entanto, esta ação não é ainda entendida. É possível que esses sistemas respondam de forma diferente às variações de estrógeno, talvez por ação direta através de receptores de estrógeno tipo em neurônios OT e AVP do PVN e SON, e por ação indireta através de receptores de estrógeno tipo em órgãos circunventriculares. O objetivo do presente trabalho foi avaliar a participação do estradiol na modulação da secreção de AVP em resposta ao estímulo osmótico induzido pela realimentação após jejum. Para tanto, foi realizada a determinação da concentração plasmática de AVP, a análise da ativação de neurônios AVP, o conteúdo protéico de ER no PVN e no SON bem como a ativação neuronal pela expressão de FOS e a expressão de ER nos órgãos circunventriculares de animais ovariectomizados tratados com estradiol ou veículo. Os resultados mostram que a realimentação após jejum de 48 horas aumenta a expressão de FOS e a expressão da proteína de ER no PVN e SON, a expressão de FOS nos órgãos circunventriculares estudados e a concentração plasmática de AVP. No entanto, não foi observada diferença significativa entre os tratamentos. Houve uma inibição da expressão de ER nos órgãos circunventriculares estudados. Aparentemente, o estradiol não participa da elaboração de uma resposta frente ao estímulo osmótico induzido pela realimentação e não interfe na ativação de neurônios AVP e na secreção desse hormônio para circulação sanguínea. / The hydroelectrolyte homeostasis is controlled by information on volume and concentration of ions in the body fluids. Osmolality changes are detected by receptors in various regions of the CNS, including the circumventricular organs. Conformational changes of these cells activate neurons located in the paraventricular (PVN) and supraoptic (SON) nucleus of the hypothalamus, which secrete oxytocin (OT) and vasopressin (AVP). Feeding increases the plasma osmolality which induces the secretion of AVP and OT. Ovarian steroids may influence the balance of fluids modulating hormonal systems that regulate both consumption and excretion of water or acting directly on oxytocinergic and vasopressinergic neurons of the hypothalamus. However, this action is not clearly understood. It is possible that these systems respond differently to the estrogen changes perhaps by direct action through estrogen receptor type in AVP and OT neurons of the PVN and SON, and by indirect action through estrogen receptor type in circumventricular organs. The objective of this study was to evaluate the participation of estrogen in the modulation of AVP secretion in response to osmotic stimulus induced by refeeding after fasting. For this purpose, we performed the determination of plasma AVP, the analysis of the activation of AVP neurons, the protein content of ER in the PVN and SON as well as activation by neuronal expression of FOS and the expression of ER in the circumventricular organs in estrogen-primed and -unprimed ovariectomized animals. The results show that refeeding after fasting for 48 hours increases the expression of FOS and ER protein in the PVN and SON, the expression of FOS in the circumventricular organs studied and plasma AVP. However, there was no significant difference between treatments with estrogen or vehicle. There was an inhibition of ER expression in the circumventricular organs studied. Apparently, estrogen does not participate in the preparation of a response to the osmotic stimulus induced by refeeding and it does not interfere in the activation of AVP neurons or the secretion of this hormone to the bloodstream.