Mj. Mckinley et al., IDENTIFICATION OF NEURAL PATHWAYS ACTIVATED IN DEHYDRATED RATS BY MEANS OF FOS-IMMUNOHISTOCHEMISTRY AND NEURAL TRACING, Brain research, 653(1-2), 1994, pp. 305-314
The distribution of Fos-immunoreactivity (Fos-IR) was studied in the b
rains of rats deprived of water for 24 or 48 h and compared with that
in brains of water-replete rats. Intense Fos-IR was observed in many n
eurons of the median preoptic nucleus (MnPO), organum vasculosum of th
e lamina terminalis (OVLT), supraoptic nucleus and hypothalamic parave
ntricular nucleus. There was less intense and sparse Fos-IR in the sub
fornical organ. In water-replete rats, Fos-IR was absent or very low i
n these regions. In other rats, cholera toxin B-gold conjugate was mic
roinjected bilaterally into the supraoptic nucleus to identify retrogr
adely labelled neurons in the lamina terminalis projecting to the supr
aoptic nucleus. similar to 30% of these retrogradely labelled neurons
in the OVLT and MnPO also exhibited Fos-IR after 48 h of water depriva
tion. These data show that neurons in the MnPO, OVLT and, to a lesser
extent, the subfornical organ probably play an important role in homeo
static responses to dehydration, such as vasopressin secretion.