Nitric oxide synthesis in locust olfactory interneurones

Area of Science:

• Neuroscience
• Biochemistry
• Insect Physiology

Background:

• Nitric oxide synthase (NOS) is a key enzyme in mammalian neuronal systems.
• The presence and function of NOS in invertebrate nervous systems, particularly in olfaction, are not well understood.
• Locusts (Schistocerca gregaria) offer a model system for studying basic neurobiological processes.

Purpose of the Study:

• To characterize the properties of nitric oxide synthase (NOS) in the locust brain.
• To determine the localization of NOS within the locust brain, focusing on olfactory centers.
• To investigate potential functional parallels between NOS in locust and mammalian olfactory systems.

Main Methods:

• Biochemical assays to characterize enzyme activity, cofactor dependence, and inhibition patterns of locust brain NOS.
• Western blot analysis using an antiserum against rat cerebellar NOS to identify and estimate the molecular mass of locust NOS.
• Immunohistochemical localization of NOS in locust brain sections, with a focus on antennal lobes and associated interneurons.

Main Results:

• Locust brain NOS exhibits properties similar to mammalian neuronal NOS, including Ca2+/calmodulin and NADPH dependence, and inhibition by arginine analogues.
• Western blot analysis identified a locust brain protein of approximately 135 kDa recognized by an antiserum to rat NOS.
• NOS is highly abundant in the locust antennal lobes, localized to specific local interneurons projecting to glomeruli, structures analogous to mammalian olfactory bulb glomeruli.

Conclusions:

• The locust brain contains a NOS enzyme with biochemical characteristics comparable to mammalian NOS.
• The abundance of NOS in the antennal lobes suggests a significant role for nitric oxide (NO) in locust olfactory processing.
• The presence of NOS in analogous structures in locusts and mammals implies conserved functions of NO in olfactory systems.