Induction of glial fibrillary acidic protein immunoreactivity in the rat dentate gyrus after adrenalectomy: Comparison with neurodegenerative changes using silver impregnation

Abstract

In the present study we performed a light microscopic anatomical comparison of adrenalectomy (ADX)-induced neurodegeneration using silver impregnation and reaction of astroglial cells using GFAP immunocytochemistry in the hippocampus of the rat. Three survival times following ADX were studied: 24 hours, 3 days, and 3 weeks. Twenty-four hours following ADX we found no degenerative changes or altered GFAP immunostaining. Three days after adrenalectomy, argyrophilic somata appeared in the granular cell layer of the dentate gyrus. Argyrophilic dendrites were seen in the molecular layer of the dentate gyrus and neuritic argyrophilia were seen in the mossy fiber layer. Induction of GFAP immunoreactivity occurred simultaneously with degeneration. Increased GFAP immunoreactivity could be observed 3 days after adrenalectomy in the molecular layer of the dentate gyrus, granular cell layer, sub and supragranular cell layer, and mossy fiber layer. Size and shape of astroglial cells were changed, and their processes in the molecular layer changed from unidirectional to randomly organized. Degeneration and astroglial reaction were more pronounced 3 weeks after adrenalectomy and both were prevented by adding corticosterone to the drinking solution. Animals that did not show degenerative changes showed no increased GFAP immunoreactivity, while both effects were confined to the dentate gyrus and mossy fiber zone. These results show that there is a close relationship between the induction of GFAP immunoreactivity in the hippocampus of the rat and neuronal degeneration in the dentate gyrus following ADX, both in time and space.

Prolonged subordination stress increases Calbindin-D28k immunoreactivity in the rat hippocampal CA1 area

“…Furthermore Sunanda Roa and Raju [31] reported that the stress-induced shrinkage of the apical tree of CA3 pyramidal neurons was accompanied with an increased number of dendritic spines of apical and basal dendrites. In line with this we did not observe degenerative changes in the hippocampus following eight days of subordination stress at present using a sensitive marker for degenerative changes [13,22,32]. One might suggest that the eight days of stress is too short to produce degenerative changes but we also did not observe degenerative changes in the hippocampus after three weeks of daily changing stressors (unpublished observations).…”

“…Therefore we studied the effect of prolonged subordination stress induced by exposure of experimental animals with a dominant male rat on the immunocytochemical distribution of CB and PV. Secondly we studied whether this stressor induced degenerative changes in the hippocampus using a sensitive marker for ongoing neurodegenerative changes [13,14,22,32].…”

“…The modified Gallyas silver impregnation procedure of Nadler and Evenson [22], which labels degenerating cell bodies and their processes, was employed as described previously [13,32]. Sections were rinsed 3 x5 rain in distilled water, pretreated 5 × 5 rain in 4.5% NaOH and 0.6% NH4NO s, and impregnated for 10 rain in 5.4% NaOH, 6.4% NH4NO~ and 0.3% AgNO> Following this step sections were rinsed 3 X 5 rain in 0.5% Na2CO s and 0.012% NH4NO 3 in 30 ethanol.…”

Intracerebral Trafficking of Lactate in vivo during Stress, Exercise, Electroconvulsive Shock and Ischemia as Studied with Microdialysis

“…The reaction was stopped by rinsing three times with the sodium acetate solution and after 8 min the sections were mounted on gelatin-chrome alun-coated slides, air-dried, dehydrated in graded ethanols and xylol and covered with DEPEX (BDH Chemicals). More details can be found in Krugers et al [39]. …”

Regulation of hippocampal α1d adrenergic receptor mRNA by corticosterone in adrenalectomized rats

“…In addition, the speed at which levels of α 1d ADR mRNA expression decreased in the dentate gyrus after adrenalectomy suggests that the changes were not due simply to a paucity of neurons. Neuronal degeneration is not apparent 24 hours after adrenalectomy, as determined by silver impregnation and glial fibrillary acidic protein immunohistochemistry (Krugers et al, 1994), and elimination of apoptotic granule cells takes 72 hours (Hu et al, 1997), yet α 1d ADR mRNA was decreased in both the medial and lateral blades of the dentate gyrus within 24 hours of adrenalectomy. Hence it seems unlikely that the decrease in α 1d mRNA observed in the hippocampal formation, and in particular the dentate gyrus, is simply due to neuronal cell loss.…”