Table 5.

Numerical density of neurons in cingulate and retrosplenial cortex in rats subjected to i.v. infusion of ZK200775, 3 mg/kg/h, or vehicle for 6 h

	Numerical density (NV; means × 106/mm3 ± SEM), n
	Vehicle	ZK200775	%
Cingulate cortex	0.158  ± 0.004 (17)	0.168  ± 0.004 (8)	6
Retrosplenial cortex	0.310  ± 0.004 (19)	0.320  ± 0.005 (11)	3

To quantitatively assess possible neuronal loss in the retrosplenial and posterior cingulate cortex 3 days after beginning of the i.v. infusion of ZK200775 or vehicle in Fischer 344 rats (Charles River), an unbiased stereological dissector technique (24) was used to estimate the mean numerical density (N_V). An unbiased counting frame (0.05 × 0.05 mm; dissector height 0.01 mm) and a high aperture (100×) oil-immersion objective were used for the sampling. The N_V for each field was determined with 5-9 dissectors. ANOVA revealed no significant difference between vehicle- and ZK200775-treated rats: F_cing(1,24) = 1.99, NS; F_retro(1,29) = 1.96, NS.