Plasticity in the Rat Hippocampal Formation following Ibotenic Acid Lesion of the Septal Region: A Quantitative [¹⁴C]Deoxyglucose and Acetylcholinesterase Study

Abstract

Summary:The local cerebral glucose utilization was measured in the hippocampal formation 3, 21, and 90 days after bilateral lesions of the medial septal nucleus and the nucleus of the diagonal band of Broca by multiple ibotenic acid injections. The CMRgl c was determined in hippocampal areas and layers and various limbic and vi sual regions by quantitative e4C]2-deoxyglucose autora diography using a computerized image-processing sys tem. Three days after lesion, CMRgl c was significantly decreased in 26 of the 38 structures examined. The most pronounced reductions were found in CA2 and CA3, the subiculum, and the parasubiculum. The CMRglc values of the 21-and 90-day postlesion groups did not differ signif icantly from control data when univariate statistics were used. However, by means of a factor analysis and subse quently a discriminant analysis as a multivariate test for group differences, significant lesion-induced CMRg 1c changes could be detected between the control group, the 3-day group, and the 90-day group. The 21-day group didThe anatomy of the cholinergic septohippocam pal pathway has been intensively investigated using tracer techniques (Swanson and Cowan, 1979; Crutcher et a!., 198 1;Chandler and Crutcher, 1983) and, more recently, monoclonal antibodies to choline acetyltransferase (ChAT) (Frotscher and 1007 not differ significantly from the controls. The data indi cate that 90 days after lesion of the medial septum! diagonal band complex (MSDB), a considerable recovery of the mean CMRgl c was found in the hippocampal region, although a normal level was not reached. In a parallel series, processing of sections for acetylcholinesterase (AChE) histochemistry revealed a severe destruction of AChE-positive fibers in the hippocampus at 3 days after lesion and a conspicuous recovery in the amount of stain able fibers and their staining intensity at 21 days postle sion. In the 90-day group, the AChE fibers recovered even further but did not reach the values of unlesioned sham-operated controls. The present study indicates that sprouting of surviving cholinergic afferents might be an important morphological substrate for CMRglc recovery in the hippocampus after MSDB lesion.

Preclinical Studies Modeling Deep Brain Stimulation for Depression

“…Confirming our hypothesis, we found that animals receiving vmPFC IBO + DBS had a significant reduction in immobility as compared with control subjects (23) (Figure 3B). One caveat related to these results, however, is that glial cells are not only spared but also increase in number after IBO administration (63,64). This is important in light of recent evidence suggesting that PFC glia might be involved in mechanisms of depressivelike behavior and antidepressant treatments in rats (65,66).…”

Role of Matrix Metalloproteinases in Delayed Neuronal Damage after Transient Global Cerebral Ischemia

“…Neurologic recovery after hippocampal injury is associated with neuroplastic responses over time (Kesslak and Gage, 1986;Schulz et al, 1992;Ramirez, 2001;Nakatomi et al, 2002). After kainate lesions in the hippocampus, MMP-9 upregulation in the dentate gyrus appeared to mediate dendritic remodeling and sprouting ).…”

Biochemical, Metabolic, and Behavioral Characteristics of Immature Chronic Hyperphenylalanemic Rats

“…Acute treatment consisted of a single injection of αMePhe (2.4 μmol/g)+Phe (5.2 μmol/g) on day 25. CMR glc in three layers of the hippocampus were analyzed in the CA1 region [100, 101]; lacunosum-molec. denotes the lacunosum-molecular layer.…”