Inhibition of Nitric Oxide Synthase Impairs a Distinct Form of Long-Ter

Introduction Nitric oxide (NO), which has demonstrated plasticity regarding processes of learning and memory, has revealed its specific function in memory formation for the honeybee. The predominant amount of NO synthase (NOS) activity has been shown to participate in the processing of olfactory information of a honeybee. A honeybee's antenna (*- Application of appetitive stimuli to the antennae of honeybees elicits extension of the proboscis (PER)) lobes are the primary centers of olfactory processing that exhibit highest NOS activity, which takes place in the brain. The lip of the mushroom body, which is involved in this process, calyces and the lateral protocerebral lobe receives input from the antennal lobs via a median and a lateral pathway; this indicates strong labeling. Neuropils of the central brain exhibited intermediate labeling. The effects of NOS activity on honeybees were revealed injecting a hemoglobin assay. The hemoglobin assay is able to detect NO and other substances (CO, etc.), therefore, these assays reveal at least two signals. By adding NOS inhibitors to the assay mixture, the first signal can be inhibited, but the second signal cannot be inhibited. The second signal includes enzymes other than NOS. Total NOS activity (*- NOS activity: defined as that part of the signal which is sensitive to NOS inhibitors added to the assay mixture) is divided into a major Ca2+ and a minor Ca2+ independent NOS activity which suggested that the existence of at least two NOS isoforms in the honeybee brain. Applying only 1 (l of 100 (l N-nitro-L-arginine or N-nitro-L-arginine methyl ester (L-NAME) 20 minutes inhibits total NOS by 80% (*-show figure 2A). Maximal inhibition of NOS was attained at an approximate conc... ...at MTM (medium term memory) is not affected by the inhibition of NOS, but that blocking the NOS in regards to LTM reduces the LTM to the "level of the single trial-induced memory," (Muller 5). It was further speculated that the NOS activity depends on a sequence of conditioning trials. It was concluded that "the initial conditioning trial leads to an amnesia-resistant LTM, independently of NOS activity, formation of amnesia-resistant LTM by the subsequent conditioning trials requires NOS activity," (Muller 5). NOS plays an important part in the retention of memory, and these findings in honeybees can be used to understand how memory works in other organisms such as vertebrates. References Journal Article Muller, Uli. "Inhibition of Nitric Oxide Synthase Impairs a Distinct Form of Long-Term Memory in the Honeybee, Apis mellifera." Neuron 1996; 16: 541-549.