Transgenic NOS Knockout Mice

The nNOS knockout mice provide a unique opportunity to explore many of the postulated functions of NO in the nervous system. In the nNOS null mice LTP induced by weak intensity tetanic stimulation was only slightly reduced (O Dell et al., 1994). This LTP was blocked by NOS inhibitors, just as it is in the wild type (O Dell et al., 1994), suggesting that eNOS expressed in the hippocampus may be more important than nNOS to LTP. 

Immunostaining with an eNOS-specific antibody reveals the same staining pattern in nNOS null mice and wild-type animals (O Dell et al., 1994). Additional retrograde messengers must exist, such as arachidonic acid, CO, or platelet-activating factor, and are likely to be required for LTP, as maximal LTP is not blocked with inhibitors of NOS (O Dell et al., 1994). 

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