The Role Of Dopamine And Other Neuromodulators As Light Signals In The Inner Retina: A Link To Night Blindness Disorders
Funder
National Health and Medical Research Council
Funding Amount
$250,250.00
Summary
Although most human activities can be performed at night as efficiently as during daytime due to the use of artificial light, normal function of the circuits underlying night vision is critical. For example, when driving at night in a poorly illuminated road where the region illuminated by the headlights is processed by the cone circuit that serves daylight in the retina whilst the peripheral areas are processed by the rod driven nighttime circuit. Impairment of night vision and of the dark-ligh ....Although most human activities can be performed at night as efficiently as during daytime due to the use of artificial light, normal function of the circuits underlying night vision is critical. For example, when driving at night in a poorly illuminated road where the region illuminated by the headlights is processed by the cone circuit that serves daylight in the retina whilst the peripheral areas are processed by the rod driven nighttime circuit. Impairment of night vision and of the dark-light switch can have fatal consequences. Night blindness is a symptom characterised by reduced vision in the dark and slow adaptation to dim light. Some congenital night blindness disorders are caused by mutations in the photoreceptor calcium channels which mediate signal transmission. Additionally, patients treated with neuroleptics, a group of drugs which affect the dopaminergic system, suffer night vision disorders. Dopamine acts as a light signal in the retina. AII amacrine cells are pivotal neurones for night vision segregating two channels (ON and OFF) which convey visual information. AII cells are modulated by dopamine and thus, represent interesting targets to study the role of dopamine in the dark-light switch. Much is know about the action of dopamine on transmission of ON signals channelled by AII cells. However, its action on the OFF channel is largely unknown. We believe that some night vision disorders originate by imbalance in the dopaminergic system in the retina and its effects on AII cells. We will test our hypothesis by studying the modulatory effect of dopamine on calcium dependent signal transmission between AII cells and their partners in the OFF channel. Our hypothesis will be further tested by using animal models in which dopamine receptor function is altered. The results of these studies will provide us with an invaluable model to understand the physiological basis of the dark-light switch and of the role of dopamine in night vision disorders.Read moreRead less
Bipolar affective disorder (BP), or manic-depressive illness, is a major cause of disability and mortality worldwide. It has a lifetime prevalence of about 1% and suicide risk of about 20%. The disorder is characterised by episodes of mania or hypomania and depression, appearing in varying succession, with or without intermission. Twin, family, and adoptive studies point to a strong genetic component leading to the development of bipolar disorder, with a heritability of the order of 80%. Yet the ....Bipolar affective disorder (BP), or manic-depressive illness, is a major cause of disability and mortality worldwide. It has a lifetime prevalence of about 1% and suicide risk of about 20%. The disorder is characterised by episodes of mania or hypomania and depression, appearing in varying succession, with or without intermission. Twin, family, and adoptive studies point to a strong genetic component leading to the development of bipolar disorder, with a heritability of the order of 80%. Yet the identification of the genetic basis of the disease has proved exceedingly difficult, with numerous studies producing no definitive data. The lack of convincing results has been interpreted as an indication of complex genetic mechanisms and underlying differences between affected families and ethnic groups. Genetically isolated populations, where most individuals descend from a small number of founders, are believed to hold great potential for understanding the genetic basis of complex diseases, such as bipolar disorder. Affected subjects in such populations are likely to share the same predisposing genes, making these genes easier to identify. During the last 10 years, we have been involved in the study of bipolar disorder in one such population, with very promising results. In this project, we propose to take the research further by collecting more affected families, confirming the current positive findings and narrowing down the search to a small region, possibly a single gene. If successful, the study will be a major breakthrough which, by identifying a molecular pathway and disease mechanism, will contribute valuable and generally valid information on the biological basis of mood disorders.Read moreRead less
Understanding The Pathophysiology Of Schizophrenia, Major Depressive Disorder And Bipolar Disorder As A Basis For Improving Treatments
Funder
National Health and Medical Research Council
Funding Amount
$804,106.00
Summary
The Applicant seeks to understand the causes of the schizophrenia, bipolar disorder and major depressive disorder, which affect over 20% of the Australian population. This research is important as drug design, based on chemical remodelling, has not significantly advanced initial breakthroughs in treating psychiatric disorders and there is now a widespread belief that new drugs will only come from understand their causes.
Understanding The Role Of Muscarinic Receptors In The Pathophysiology Of Depression And Bipolar Disorder
Funder
National Health and Medical Research Council
Funding Amount
$480,074.00
Summary
The causes of bipolar disorder and major depressive disorder, which effect many Australians, remain unknown. We have recently shown decreases in muscarinic receptors in the brain of people with bipolar disorder and major depressive disorder. Muscarinic receptors are important in maintaining the functions of the brain that seem to be affected in people with bipolar disorder and major depressive disorder. Here we seek to understand how changes in muscarinic receptors occur in both disorders.
Anti-Estrogens - A Potential Treatment For Bipolar Affective Disorder In Women?
Funder
National Health and Medical Research Council
Funding Amount
$239,250.00
Summary
Bipolar Affective Disorder (BPAD) or Manic-Depressive Illness is a serious mental illness with high morbidity and mortality. The cause of the illness is still unclear and the underlying neurochemical changes are different for the manic phase compared with the depressive phase. The current treatments for BPAD are limited in scope and not biochemically well understood. There are gender differences in the presentation and outcomes for BPAD which adds to the complexity of the illness. We are proposi ....Bipolar Affective Disorder (BPAD) or Manic-Depressive Illness is a serious mental illness with high morbidity and mortality. The cause of the illness is still unclear and the underlying neurochemical changes are different for the manic phase compared with the depressive phase. The current treatments for BPAD are limited in scope and not biochemically well understood. There are gender differences in the presentation and outcomes for BPAD which adds to the complexity of the illness. We are proposing a study to develop a new type of treatment for the manic phase of BPAD and are exploring the use of anti-estrogens in women with mania. The background to our proposed study comes from a few case reports suggesting that anti-estrogen agents such as progesterone and tamoxifen may be useful adjuncts to treatment. We conducted a small pilot study comparing the addition of oral tamoxifen with oral progesterone and placebo in 10 women with mania and found that the women who received tamoxifen made significantly better improvements in their manic symptoms over a 28-day trial. The research study we are now proposing is a larger, three-arm, double blind, placebo controlled, 28-day adjunctive study in women with mania to expand and clarify our pilot study findings. Patients in our proposed study would receive either 40mg per day tamoxifen or 20mg per day progesterone or placebo in addition to standardised lithium medication. We will measure enzyme activity (protein kinase C) and estrogen-progesterone levels to understand more about the mechanisms of action by these new hormone treatments. BPAD is a crippling disorder and if we are successful, then tamoxifen treatment may be an important new treatment. This proposed study will also shed new light on some of the neurochemical mechanisms underlying BPAD as well as opening up the new area of hormone treatments for serious mental illness.Read moreRead less
Differential Changes In Cortical Tumour Necrosis Factor Signalling In Mood Disorders And Schizophrenia
Funder
National Health and Medical Research Council
Funding Amount
$642,078.00
Summary
Changes in inflammation-related pathways contribute to the symptoms of psychiatric disorders and tumour necrosis factor ? (TNF) is a protein central to regulating theses pathways. We have now shown that changes in pathways regulated by TNF are present in the brains of people with schizophrenia and mood disorders. This means that the symptoms experienced by those with the different disorders may be linked to differential changes in TNF-regulated pathways in the brain.
Brain Stimulation Therapeutics For Mental Health Disorders: From Concept To Clinical Application
Funder
National Health and Medical Research Council
Funding Amount
$2,116,312.00
Summary
This fellowship application will support a program of research to develop and expand the use of a number of forms of non-invasive brain stimulation. These will be used to dramatically enhance the range of therapeutic options available for patients with common mental health conditions such as depression. This will include trials to advance the application of existing treatments, develop a fundamentally new home based device therapy and support a new clinical trials network.