Long-term potentiation persistence greater in C57BL/6 than DBA/2 mice: predicted on basis of protein kinase C levels and learning performance.
The gamma isoform of protein kinase C (gamma-PKC) activity is elevated and learning is superior in the inbred C57BL/6 mouse when compared to the DBA/2 mouse strain. Given the proposed link between PKC and long-term potentiation (LTP) on the one hand and PKC and learning on the other, it was predicted that LTP persistence would be greater in C57BL/6 mouse. When suprathreshold levels of tetanic stimulation were used, similar persistent LTP was observed in both C57BL/6 and DBA/2 strains. However, when tetanus was at threshold, the response in DBA/2 mice decayed to baseline in 30 min, similar to short-term potentiation (STP). Using this same paradigm with C57BL/6 mice, LTP persisted for 4 h, the longest time tested. The time course of the results parallels those observed in rat when phorbol ester, a potent PKC activator, converts STP to LTP. The present findings thus confirm the predicted difference between the two mouse strains. Moreover, the present findings are consistent with a role for gamma-PKC in LTP. Since such results call attention to the need for gamma-PKC interventive procedures, the relative utility of current PKC inhibitors, null mutants and antisense methods are discussed.
Matsuyama
S
S
Department of Pharmacology, Kobe University School of Medicine, Japan.
Namgung
U
U
Routtenberg
A
A
D000818:Animals; D007858:Learning / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D011493:Protein Kinase C / Q000378:metabolism*
D011493:Protein Kinase C