Publication Date


Degree Program

Department of Biology

Degree Type

Master of Science


Gamma aminobutyric acid (GABA) is a prominent neurotransmitter found in both vertebrates and invertebrates. The action of GABA has been accepted to be inhibitory in nature, but recent evidence suggests it is both inhibitory and excitatory, depending upon time of day. The amount of GABA measured in the brain of the cockroach Leucophaea maderae was discovered to fluctuate in a circadian pattern similar to the pattern of electrical output measured from the optic nerve in L. maderae. Considering the circadian oscillator for L. maderae has been localized to the optic lobes of the brain, the discovery of GABA-like immunoreactivity in the optic lobes and optic tract could be an important first step in localizing cells that comprise the circadian oscillator(s) that control the temporal pattern of many physiological, biochemical and behavioral activities, such as locomotor activity and metabolism. Through the use of monoclonal antibodies and the enzyme alkaline phosphatase, GABA-like immunoreactivity has been discovered associated with neuropils of the optic lobes (lamina, medulla, lobula) and in the optic tract of the cockroach L. maderae. The localization of GABA-like immunoreactivity in the optic lobes and tract of L. maderae is consistent with findings in other invertebrates, including other species of cockroaches.


Medical Sciences