Effects of Endogenous Pyrogen and Prostaglandin E_2 on Preoptic and Anterior Hypothalamic Neurons in Slice Preparation of Guinea-pig

To investigate the effects of EP and PGE_2 on the activity of the neuron in the PO/AH, single unit activity was recorded from in vitro brain tissue slices prepared from the PO/AH of guinea-pigs. Of 94 PO/AH neurons studied, 81% of the neurons was warm-responsive neuron, 3% cold-responsive and 16% temperature-insensitive neurons. With an application of EP into perfusate, 41% of 73 warm-responsive neurons altered their activities. The same proportion of 51 warm-responsive neurons as the effects of EP application was also observed with PGE_2 administration. However, these changes in the firing rate varied depending upon their own thermosensitivities. When perfusate was substituted by low Ca^<2+>, high Mg^<2+> Krebs-Ringer solution, 40% of the temperature-responsive neurons lost their thermosensitivities. The temperature-responsive neurons remaining their thermosensitivities did not show any changes of response to EP or PGE_2 before, during and after synaptic blockade.