Effects of Hydrocephalus and Surgical Decompression on Cortical Norepinephrine Levels in Neonatal Cats

Norepinephrine (NE) changes during hydrocephalus, and the effects of surgical decompression on these changes, were studied using a new model of neonatal hydrocephalus. Kittens 4 to 10 days old received intracisternal injections of a sterile solution of 25% kaolin. Controlkittens were injected similarly with sterile injectable saline. A subgroup of hydrocephalie animais was shunted using a cerebrospinal fluid lumbar-peritoneal catheter. Hydrocephalie animais were killed at approximately 25 days of age (16-21 days after kaolin injection). Surgical decompression was performed at 12, 16 and 17 days after kaolin injection; these animais were killed 30 days after the shunts were inserted. Control animais were killed at 29 and 53 days of age, to correlate with the ages of the hydrocephalie and shunted animais, respectively. Cortical samples equivalent to Brodmann’s areas 4, 22 and 17 were measured for NE using high-performance liquid chromatography. Hydrocephalus caused NE levels to decrease significantly in ail cortical areas. These alterations followed a rostrocaudal gradient in severity, with mean reductions of 65.8, 83.9, and 95.8% in areas 4, 22, and 17, respectively. Partial recovery oecurred in animais that received shunts 16 and 17 days after kaolin injection, such that NE reductions of 75.7, 56.2, and 81.6% were noted in areas 4, 22, and 17, respectively. Shunting at 12 days after kaolin injection produced complete recovery in areas 4 and 22, with only a 67.7% decrease in area 17.