Table 1.

Summary of dynorphinergic synaptic bouton features

Animal group	Mean bouton area (μm2 ± SEM)	Mean active zone length (μm ± SEM)	Postsynaptic density	Perforated synapses	% Targets with dynorphin	Postsynaptic target
						Spine	Dendritic shaft	Soma
VEH-treated	0.53  ± 0.06	0.32  ± 0.02	84% symmetrical	8.2%	30%	3.6%	76.8%1-161	3.4%
			16% asymmetrical
VCM−	0.40  ± 0.05	0.26  ± 0.01	82% symmetrical	4.6%	41%	6.3%	77.1%1-161	6.1%
			18% asymmetrical
VCM+	0.60  ± 0.05	0.31  ± 0.02	73% symmetrical*	13.8%	23%†	29.8%‡	56.4%	2.1%
			27% asymmetrical1-160

The cross-sectional terminal areas and active zone lengths were compared across groups (one-way ANOVA). Other synaptic variables were rated as present or absent for each group, and odds ratios were used to predict the chances of each variable being present (or absent) in VCM+ rats as compared with the odds of that feature occurring (or not occurring) in the absence of VCMs (VCM− and VEH-treated groups combined).

When compared with VEH-treated and VCM− animals,

^*dynorphin-immunolabeled terminals of VCM+ rats make significantly fewer symmetrical contacts (p = 0.01),

F1-160: dynorphin-immunolabeled terminals of VCM+ rats are significantly more likely to end in an asymmetrical specialization (p = 0.035),

^†dynorphin-immunolabeled terminals in VCM+ rats contact significantly fewer dynorphin-positive targets (p = 0.006), and

^‡dynorphin-immunolabeled terminals in VCM+ rats contact significantly more spines (p = 0.003).

When compared with VCM+ animals,

F1-161: dynorphin-immunolabeled terminals in VCM− and VEH-treated rats contact significantly more dendritic shafts (p = 0.003).