Bax protein-like immunoreactivity in primary sensory and hypothalamic neurons of adult rats.

Bax protein-like immunoreactivity (Bax-ir) was examined in the perfusion-fixed, cryosectioned rat nervous system. In the central nervous system, hypothalamic neurons were the only neurons that exhibited Bax-ir in the cell body. Their axons traveled toward the median eminence, suggesting that the Bax-like immunoreactive (Bax-ir) hypothalamic neurons included neurosecretory ones. Bax-ir axons were observed in the solitary tract nucleus, and spinal and medullary dorsal horns. They appear to have been derived from Bax-ir primary sensory neurons in the viscerosensory nodose ganglion and somatosensory dorsal root and trigeminal ganglia. In the somatosensory ganglia, smaller cells exhibited stronger Bax-ir. Accordingly, the ir axons in the dorsal horn were most concentrated in lamina II.