By René A. Azeez, Honours BSc. Developmental Biology, University of Toronto. July 25, 2011.
British Baptist preacher Charles Haddon Spurgeon said of anxiety, “Anxiety does not empty tomorrow of its sorrows, but only empties today of its strengths.” Fear, which can be defined as an emotional response to a perceived treat, differs from anxiety in that anxiety can often occur without an identifiable triggering stimulus. Anxiety is defined as having both psychological and physiological constituents and is characterized by “somatic, emotional, cognitive, and behavioral components.” Researchers from Queen’s University, Kingston, Ontario, have come one step closer in identifying a new method for regulating anxiety. Prior to the study, it was understood that neuropeptide Y (NPY) is one of the most abundant chemicals in the mammalian brain and that NPY counteracts the responses to acute threat in animal models. It was also known that intracerebroventricular (i.c.v) administration of NPY is anxiolytic (anxiety reducing). However, less had been known about the particular contributions of the area of the brain known as the lateral septum as relates to NPY-regulated anxiety reduction. NPY-like-immunoreactivity is highly expressed in the lateral septum.
The study lead by Dr. Natalie L. Trent, of the Queen’s University’s Centre for Neuroscience Studies, was designed to investigate the effects of NPY infusions into the lateral septum across a range of anxiety related behaviors and to examine the effects of antagonizing NPY Y1 receptors on anxiety responses.
Rats were tested in three paradigms. The first is called the plus-maze test, in which it was found that NPY infusion into the lateral septum had no effects on the anxiety equitable behaviors as determined by the test. Furthermore, introduction of both NPY and Y1 antagonist (BIBO 3304) yielded the same result. A second test called the novelty-induced suppression of feeding test, found that rats were significantly quicker in initiating snack consumption following their first infusion of NPY, indicating a reduction in anxiety. This anxiolysis was attenuated when NPY and Y1 antagonist were co-infused into the lateral septum. The third test, called the shock-probe burying test showed that rats spent less time burying an electrified probe, a marker of reduced anxiety, after being infused with NPY. However, in this case, the Y1 antagonist did not attenuate anxiolysis. The results were enough to conclude that activation of NPY receptors in the lateral septum reduced anxiety-related responses, albeit in a test specific manner. This observation makes investigating the potential role of other NPY receptors (Y2 and/or Y5) in anxiolysis of particular interest.
The researchers hope that the finding will lead to more selective treatment options for anxiety disorders.
REFERENCE:
Trent N. L., Menard J. L. Infusions of neuropeptide Y into the lateral septum reduce anxiety-related behaviors in the rat. Pharmacology, Biochemistry, and Behavior. 2011 (99): 580-590.
