Quick Project Snapshot

Control of complex behaviour by neuropeptides

Our laboratory is part of the Neuropeptides Division of The Florey Institute of Neuroscience and Mental Health and our research is in the broad area of systems neuroscience. Our main research interest is in the role of neuropeptide signalling in the control of complex behaviours such as arousal, stress and mood, and associated cognitive and memory processes under normal and neuropathological conditions. We are researching the neurobiology of the relaxin-3/RXFP3 (peptide-receptor) system in brain, as well as the role of the neural network driven by an area known as the nucleus incertus. Senior scientists in the laboratory offer a range of distinct research projects that involve studies in experimental animal models of health and psychiatric disease (in normal and transgenic mice), using a range of biomolecular tools, including receptor-selective peptides and viral-vector delivered - neural tracing molecules, receptor-targeting peptides, ‘DREADDs’ (designer receptors exclusively activated by designer drugs) or optogenetic, light-activated channelrhodopsins. The different projects are suitable for Honours or PhD students and are detailed below.  

1. Relaxin-3/RXFP3 signalling in limbic networks in emotional and social behaviour in mice – transgenic and viral pharmacogenetic studies The neuropeptide relaxin-3 is expressed by GABA neurons in the nucleus incertus (NI) and these neurons innervate and modulate neural circuits that regulate stress- and arousal-related ‘motivated’ or goal-directed behaviours. These neurons appear to target and inhibit mostly GABA neurons in the limbic brain (i.e. GABA cells expressing RXFP3) and likely regulate amygdala and frontal cortex circuits that control emotional and social behaviours, including fear and anxiety, social recognition and/or aggression, as well as associated cognitive processes [1-5]. In this project, we are employing molecular tools and techniques, and transgenic mouse strains to determine the effect of NI (and relaxin-3/RXFP3) activity on anxiety, social and other behaviours. We are using excitatory and inhibitory DREADDs [6] delivered into the brain using viral vectors to regulate the activity of target neurons.  Mice undergo testing in specific validated assays of behaviour; and the effects of excitatory or inhibitory DREAAD activation in NI neurons by peripheral injection of the designer ligand, clozapine-N-oxide (CNO) are assessed using state-of-the-art equipment and video analysis. Studies are also examining the effect of relaxin-3 and RXFP3 gene deletion on these behaviours and whether centrally-injected RXFP3 agonist or antagonist peptides alter responses in anxiety and social recognition tests. Effects of DREADD and peptide receptor activation on brain activity patterns are assessed using neurochemical assays and quantitative measures of gene expression. These studies will help reveal the role of nucleus incertus circuits and relaxin-3 transmission in the modulation of affective behaviour and be extended to studies in genetic models of social, cognitive and other deficits seen in psychiatric illnesses. Students will receive training in neurochemical anatomy, physiology and behaviour and techniques including stereotaxic surgery for peptide and viral delivery; behavioural assays and analysis; mRNA/peptide/protein analysis; and light/confocal microscopy.  

  1. Ma S et al. (2007) Neuroscience 144: 165-190
  2. Smith CM et al. (2010) J Comp Neurol 518: 4016-4045
  3. Ryan PJ et al. (2011) Neurosci Biobehav Rev 35: 1326-1341
  4. Smith CM et al. (2011) J Chem Neuroanat 42: 262-275
  5. Ma S et al. (2013) J Physiol (Lond) 591: 3981-4001
  6. Krashes MJ et al. (2011) J Clin Invest 121: 1424-1428  

 

2. Relaxin-3/RXFP3 signalling in control of ‘behavioural state’ - arousal and related behaviours in mice Sleep and wakefulness are controlled by brain circuits referred to as ‘arousal pathways’. These pathways facilitate heightened awareness, attention and cognition, and are also implicated in ‘reward signals’ associated with food- and drug-seeking behaviour. Established arousal systems include serotonin neurons in the raphé nuclei and dopamine neurons in the ventral tegmental area, and orexin peptide neurons in lateral hypothalamus [1,2]. Anatomical and functional studies suggest relaxin-3 neurons in nucleus incertus (NI) and periaqueductal grey (PAG) represent an arousal pathway that modulates a range of behaviours such as feeding, attention, motivation and exploratory behaviour [3-8]. Mice genetically lacking relaxin-3 display a circadian hypoactivity and may represent a model for aspects of clinical depression [4-7]. Therefore, the brain relaxin-3/RXFP3 system represents a potential target for drugs to treat conditions such as insomnia, anorexia, obesity, drug abuse and depression. These studies utilise unique mouse strains, including conditional RXFP3 knockout (KO) and RXFP3-Cre reporter lines, highly selective relaxin-3 receptor (RXFP3) agonist and antagonist peptides and viral-driven peptide vectors, and state-of-the-art equipment and behavioural paradigms to determine the behavioural effects of relaxin-3 and RXFP3 deficiency. Relaxin-3 and RXFP3 KO mice have been shown to display hypoactivity in novel environments and other characteristics of mood disturbances. These mice and a new conditional RXFP3 KO will be characterised by testing their performance versus ‘wild-type’ littermates on running wheels, and by measuring 24 h sleep/wake patterns and motivated and mood related behaviours. We will also conduct assessments of the baseline responses of the conditional RXFP3 KO mice in a range of behavioural tests to identify any new phenotypes associated with deletion of the receptor in adulthood. The ability of acute or chronic central RXFP3 activation to ‘rescue’ behavioural alterations in relaxin-3 KO mice can also be determined using acute central injections of an RXFP3 agonist peptide and/or a viral-driven RXFP3 agonist peptide.  

  1. Fuller PM et al. J Biol Rhythms 21 (2006) 482-493  
  2. Sakurai T. Nature Rev Neurosci 8 (2007) 171-181
  3. Gundlach AL et al. Ann NY Acad Sci 1160 (2009) 226-235
  4. Smith CM et al. Ann NY Acad Sci 1160 (2009) 236-241
  5. Smith CM et al. J Comp Neurol 518 (2010) 4016-4045
  6. Smith CM et al. J Chem Neuroanat 43 (2011) 262-275
  7. Smith CM et al. Genes Brain Behav 11 (2012) 94-104
  8. Blasiak A et al. Eur J Neurosci 37 (2013) 1284-1294
  9. Ryan PJ et al. Proc Natl Acad Sci USA 110 (2013) 20789-94

3. Role of relaxin-3 neurons and RXFP3 signalling in fear memory and stress-related cognitive dysfunction in rat brain -  Anxiety disorders are one of the most prevalent mental illnesses in society and include generalized anxiety-, phobic-, panic- and post-traumatic stress- disorders (PTSD). Research has identified a core feature of anxiety disorders is impairment of fear memory extinction or ‘safety learning’. Relaxin-3 and its receptor, RXFP3 are present in brain regions associated with stress and fear behaviour, and the relaxin-3/RXFP3 network is involved in behavioural activation, arousal and cognition. Stress strongly activates relaxin-3 neurons and increases relaxin-3 gene expression. We have observed that central RXFP3 activation in the amygdala, a brain region critical for fear memory and extinction, significantly reduced fear behaviour in rats and reduced memory of the fear the following day. Our current research is extending the investigation of relaxin-3/RXFP3 effects on fear memory by examining the impact of stress on the relaxin-3/RXFP3 system in a rodent model of chronic stress and anxiety, comparable to human anxiety and PTSD. The project involves fear conditioning studies in rats and provides training in stereotaxic surgery, animal handling, behavioural testing (fear conditioning) and analysis, and advanced histology techniques.  

  1. Ma S et al. (2007) Neuroscience 144: 165-190
  2. Ma S et al. (2009) Learn Mem 16: 730-742  
  3. Banerjee A et al. (2010) Neuropharmacology 58: 145-155  
  4. Smith CM et al. (2011) J Chem Neuroanat 42: 262-275  
  5. Ehrlich I et al. (2009) Neuron 62: 757-771  
  6. Ma S et al. J Physiol (Lond) 591 (2013) 3981-4001
  7. Ryan PJ et al. Proc Natl Acad Sci USA 110 (2013) 20789-94  

4. Functional topography of serotonin (5-HT) and peptide (relaxin-3) systems in the control of anxiety-like behaviour -  Anxiety disorders are a major health issue and it is thought that dysfunction of brain stress pathways underlie their pathology. Further research is required to better understand the nature of normal neurotransmission associated with innate anxiety and stress responses to provide insights into psychiatric illness. The monoamine transmitter, serotonin (5-HT) and the peptide, corticotropin-releasing factor (CRF) have recognised roles in the control of stress and anxiety and recent studies indicate that relaxin-3 signalling may also be involved. Therefore, these studies are assessing the anatomical and functional relationship of neural networks that utilise serotonin, CRF and relaxin-3 as neuromodulatory transmitters and their possible interactive role in controlling innate anxiety-like behaviour. Previous studies have determined the neuroanatomical distribution of groups of serotonin-containing neurons in the various raphe nuclei and major groups of relaxin-3 containing neurons in distinct populations of GABA neurons in the nucleus incertus (NI) and periaqueductal grey (PAG) and the likely separate functions of subgroups of these 5-HT and relaxin-3 neurons and their regulation by stress. These studies will help identify structural and functional interactions between separate components of two ascending modulatory networks that regulate sensorimotor behaviours and associated cognitive processes, including arousal and motivation, feeding and metabolism, biorhythms, and emotional responses such as fear and anxiety in health and disease and will lay the foundation for pharmaco- and optogenetic analysis of topographic relaxin-3 and 5HT pathways.  

  1. Ma S et al. Neuroscience 144 (2007) 165-190
  2. Smith CM et al. J Comp Neurol 518 (2010) 4016-4045
  3. Smith CM et al. J Chem Neuroanat 42 (2011) 262-275
  4. Ryan PJ et al. Behav Brain Res 244 (2013) 142-151
  5. Hale MW, Lowry CA. Psychopharmacology (Berl) 213 (2011) 243-26
  6. Hale MW et al. Neuroscience 157 (2008) 733-748
  7. Kelly KJ et al. Neuroscience 197 (2011) 251-268

 

5. Additional Research Projects (under development) In collaboration with other scientists and laboratories within the Neuropeptides and other Florey Divisions and international laboratories in Europe, we continue to develop new molecular tools and assays and survey additional animal models of physiology and pathology to probe the nature of brain relaxin-3/RXFP3 and their interactions with other related neurotransmitter and neuromodulatory systems. These include the development of specific promoter sequences to facilitate the targeting of particular neuron populations, studies of mouse models of neurodegeneration, maternal/aggressive behaviour, and descending control of chronic pain; and assays to assess synaptic plasticity and neurochemical alterations in response to altered RXFP3 signalling. We are also working with staff of the Florey Bioinformatics platform to produce new insights into possible genetic links between relaxin-3 systems and neurodegenerative and psychiatric disease. 

 

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HEAD OF LAB
Prof Andrew Gundlach

Peptide Neurobiology Laboratory

Dementia and psychiatric illnesses remain major clinical, scientific, societal and economic problems. A better understanding of how the brain controls physiology and behaviour and how this becomes dysfunctional due to ageing and disease pathology is urgently required. Basic research studies are therefore needed to identify new structural and molecular neural targets that may form the basis of novel therapeutic approaches in the future. In this regard, our laboratory conducts ‘systems neuroscience’ research and a primary interest is to understand the role of neuropeptide signalling in the control of complex behaviours including arousal, stress, mood motivation and reward, and associated memory processes, under normal and pathophysiological conditions. We conduct experimental studies in animal models of normal physiology and psychiatric disorders, using a range of biomolecular tools including receptor-selective peptides, ‘viral-vector delivered’ designer receptors, and a range of transgenic mouse strains.

All Projects by this Lab

Control of complex behaviour by neuropeptides

Neuropeptides

The Neuropeptides Division primarily conducts multi-disciplinary studies on the relaxin family of peptides/hormones and their receptors. The division focuses on determining the role of these peptides and the receptors they target a wide range of physiological and disease states. These studies are coupled with fundamental drug discovery research on both these and other peptides and their G protein-coupled receptors. The aim of this research is to develop new biological knowledge and fundamental understanding about how to best therapeutically target these peptide systems with the long term view to develop drugs which target the peptide receptors to treat vascular, fibrotic, metabolic and psychiatric diseases.

An example of the success of this approach is the completion of a Phase III trial using the hormone relaxin for the treatment of acute heart failure by the Swiss Pharmaceutical Company Novartis. A Phase IIIb trial is ongoing and the relaxin drug, serelaxin, has been approved in Russia to treat patients with acute heart failure. Hence fundamental research on the mechanism of action of a hormone, in the case of relaxin pioneered at the Florey by the former Neuropeptides Division Head, Prof Geoffrey Tregear, can ultimately lead to its use to treat disease in patients.

All Labs that operate in this Division

Insulin Peptides GroupNeuropeptide Receptor GroupPeptide and Protein Chemistry LaboratoryPeptide Neurobiology LaboratoryReceptor Structure and Drug Discovery Laboratory