Nitric oxide as a putative messenger molecule in the crayfish olfactory midbrain

Area of Science:

• Neuroscience
• Crustacean neurobiology
• Olfactory system research

Background:

• Nitric oxide synthase (NOS) plays a role in neuronal signaling.
• The olfactory system in crayfish is crucial for detecting environmental cues.
• Understanding neuronal pathways in invertebrates offers insights into fundamental biological processes.

Purpose of the Study:

• To investigate the presence and distribution of nitric oxide synthase (NOS)-containing neurons in the crayfish olfactory midbrain.
• To characterize the neuroanatomical features of these NOS-containing interneurons.
• To explore the functional impact of nitric oxide on olfactory lobe activity in crayfish.

Main Methods:

• NADPH-d histochemistry was employed to identify presumptive NOS-containing neurons.
• Anatomical tracing of neuronal projections within the olfactory midbrain.
• Local field potential recordings were used to assess the effects of NOS-related compounds on neuronal activity.

Main Results:

• Three distinct types of local olfactory interneurons exhibiting NADPH-d activity were identified.
• These interneurons included two pairs of large interneurons and positively stained globuli cells.
• Administration of nitric oxide donors (SNP, SIN-1) resulted in reversible inhibitory effects on electrically-evoked responses in the olfactory lobe.

Conclusions:

• Crayfish olfactory midbrain contains distinct populations of NOS-containing interneurons.
• These neurons project within the ipsilateral olfactory and accessory lobes, with limited innervation of glomeruli.
• Nitric oxide appears to exert an inhibitory influence on neuronal activity within the crayfish olfactory lobe.