Lesions of tuberomammillary nuclei induce differential polydipsic and hyperphagic effects.
Hypophysial stalk-transected (ST) and sham-operated animals were subjected to a chronic intermittent salt loading regimen (CISL) for 14 days beginning 1 day post surgery (dps). Animals were sacrificed at 15 and 36 dps. Three days after the termination of CISL, water consumption in ST + CISL animals decreased to the same level as that of sham-operated animals, while that of ST + water animals was maintained at a significantly higher level. The number of the surviving vasopressinergic neurons in the supraoptic nuclei of the ST + CISL group was significantly higher than that of ST + water group. CISL induced vasopressinergic axonal sprouting into the external zone of the median eminence, and formation of subependymal perivascular plexus. While CISL also enhanced regeneration of oxytocinergic axons into the external zone, it did not, however, have any effect on the number of oxytocinergic neurons surviving axotomy.