To understand neural mechanisms of reproductive physiology, we have generated promoter transgenic rats for gonadotropin-releasing hormone (GnRH) neurons. Using these rats we have analyzed ion channels expressed in rat GnRH neurons by means of patch clamp experiments and reverse transcriptase-polymerase chain reaction. The study revealed that rat GnRH neurons exhibit voltage-gated Na+, K+ and Ca2+ currents. There are delayed rectifier K+ currents, large conductance voltage- and Ca2+ -activated K+ currents (BK currents carried through BK channels) and Ca2+ -activated K+ currents (slow afterhyperpolarization currents carried through SK channels). Ca2+ currents are carried through five different Ca2+ channels, namely L-, N-, P/Q-, R- and T-types. Activation of these ion channels determines excitability of GnRH neurons and their firing pattern of action potentials.