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. 1999 Mar 15;19(6):2037–2050. doi: 10.1523/JNEUROSCI.19-06-02037.1999

Fig. 4.

Fig. 4.

Comparison of spontaneous action potentials in GFP-expressing GnRH neurons with those in neighboring nonfluorescent, non-GnRH hypothalamic neurons. A, Fluorescence (left) and IR-DIC (right) images of a GFP-expressing GnRH neuron (1) and a neighboring nonfluorescent neuron (2) during a whole-cell patch-clamp recording of action potentials in the GnRH neuron. The neurons were in the DBB of a sagittal brain slice from a P21 female GnRH-GFP mouse. B, Spontaneous action potentials with long afterhyperpolarizations in GFP-expressing GnRH neurons in the POA of a P44 male GnRH-GFP mouse (left) and in the DBB of a P19 male GnRH-GFP mouse (right). Calibrations in this panel and in C are the same. C, Six shapes of spontaneous action potential in nonfluorescent neurons neighboring GFP-expressing GnRH neurons. Top left, Action potentials in a nonfluorescent neuron neighboring the GnRH neuron whose action potential is shown in the left traceof B. These action potentials are characterized by a brief afterhyperpolarization, followed by a slow return to the resting potential. Action potentials of this shape were observed in 15 of 26, or 58% of, nonfluorescent neurons. Each of the other action potential shapes shown below was seen in ≤15% of nonfluorescent neurons. Top right, Action potentials in a nonfluorescent neuron neighboring the GnRH neuron whose action potentials are shown in the right trace ofB. In this case, the brief afterhyperpolarization was followed by a fast return to the resting membrane potential.Middle left, Action potentials with a biphasic afterhyperpolarization in a nonfluorescent neuron in the DBB of a 6-month-old female GnRH-GFP mouse. Middle right, Action potentials with little or no afterhyperpolarization in a nonfluorescent neuron in the POA of a P23 female GnRH-GFP mouse. Bottom left, Action potential with an afterhyperpolarization, followed by an afterdepolarization, in a nonfluorescent neuron in the POA of a P42 male GnRH-GFP mouse. Bottom right, Large action potential, followed by a small action potential and afterdepolarization but no afterhyperpolarization, in a nonfluorescent neuron in the DBB of a P15 male GnRH-GFP mouse.