scholarly journals Local circuit neurons in both the dentate gyrus and Ammon's horn establish synaptic connections with principal neurons in five day old rats: a morphological basis for inhibition in early development

1989 ◽  
Vol 78 (1) ◽  
Author(s):  
L. Seress ◽  
M. Frotscher ◽  
C.E. Ribak
Keyword(s):  
Dentate Gyrus ◽  
Early Development ◽  
Synaptic Connections ◽  
Ammon's Horn ◽  
Local Circuit ◽  
Local Circuit Neurons ◽  
Morphological Basis ◽  
Old Rats ◽  
Ammon’S Horn

Postnatal Development of the Hippocampus in Male Albino Rats: A Histomorphometric Study

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
A A A Baraka ◽  
K A Hafez ◽  
A I A Othman ◽  
A M M Sadek
Keyword(s):  
Dentate Gyrus ◽  
Postnatal Development ◽  
Learning And Memory ◽  
Hippocampal Formation ◽  
Critical Role ◽  
Mammalian Brain ◽  
Albino Rats ◽  
Ammon's Horn ◽  
Hippocampus Proper ◽  
Ammon’S Horn

Abstract Introduction In recent year deterioration in cognitive, learning, and memory become one of the significant problems in human life. Hippocampus is a pivotal part of the brain’s limbic system which serves a critical role in memory, learning process and regulating the emotions. In most regions of the brain, neurons are generated only at specific periods of early development, and not born in the adulthood. In contrast, hippocampal neurons are generated throughout development and adult life. The hippocampal dentate gyrus was reported to be one of the few regions of the mammalian brain where neurogenesis continue to occur throughout adulthood. The neurogenesis in the dentate gyrus was thought to play an important role in hippocampus-dependent learning and memory. The hippocampal formation is composed of the hippocampus proper, the dentate gyrus and the subiculum. The hippocampus proper is the largest part and is subdivided into fields designated as Cornu Ammonis or Ammon’s horn (CA) from CA1 to CA4. Ammon's horn is continuous with the subiculum, which acts as the main output source of the hippocampal formation. Aim of the Study To study the postnatal development of the hippocampal formation. Materials and Methods Five male albino rats from the following postnatal ages day 1, week 1, week 2, week3 and week 4 were studied by histological, immunohistochemical, and morphometric methods. Results The general architecture of the hippocampus proper with its polymorphic, pyramidal, and molecular layers was present at day1, whereas the details of the adult structure appeared at week 2. In the dentate gyrus, distinct lamination appeared at week 1 and its maturation continued with the production of neurons at the interhilar zone that peaked at week 2. The number and density of pyramidal axons and dendrites increase by age. Astrocytes increased in size and staining affinity for glial filaments, and acquired a stellate shape with age. Furthermore, the number of granule cell layers increased concomitantly with the increase in thickness of the molecular and polymorphic layers of both the hippocampus proper and the dentate gyrus. Conclusion The important sequences of events in the growth and maturation of the hippocampal formation in male albino rat occurred in the first 2 postnatal weeks.

scholarly journals In vitro hippocampal uptake of tritiated serotonin (3H-5HT): A morphological, biochemical, and pharmacological approach to specificity.

1980 ◽  
Vol 28 (7) ◽  
pp. 636-644 ◽  
Author(s):  
E C Azmitia ◽  
W F Marovitz
Keyword(s):  
Dentate Gyrus ◽  
Linear Regression Analysis ◽  
Hippocampal Slices ◽  
Stratum Radiatum ◽  
Ammon's Horn ◽  
Uptake Mechanism ◽  
Cingulum Bundle ◽  
Specific Uptake ◽  
Ammon’S Horn

The in vitro uptake of tritiated serotonin (3H-5HT) into hippocampal slices was measured in Ringer's solution (37 degrees C) containing pargyline, ascorbic acid, and dextrose. The specific uptake of 3H-5HT rose asymptotically as the 3H-5HT molarity was increased from 5 x 10(-10) to 1.5 x 10(-6) M. Linear regression analysis gave a Km value for the specific uptake of 1.4 x 10(-7) M. The nonspecific binding (NSB) was the amount of 3H-5HT retained by the slices following incubation in a medium with a very large excess of unlabeled 5-HT added to dilute the specific uptake of 3H-5HT. This NSB increased with increasing molarity of 3H-5HT, and was linearly related to 3H-5HT concentrations between 5 x 10(-9) and 1.5 x 10(-6) M. The ratio of specific uptake to NSB was highest at 5 x 10(-8) M (2.75) and lowest at 1.5 x 10(-6) M of 3H-5HT (0.54). Competition studies with noradrenaline, desipramine (a noradrenergic uptake blocker), fluoxetine (a 5-HT uptake blocker), and tryptophan confirmed the specificity of the 3H-5HT uptake mechanism. Radioautographic studies of in vitro incubated hippocampal slices showed silver grain aggregates at 3H-5HT specific uptake sites. Addition of an excess of unlabeled 5-HT to the slices, or the use of hippocampi from 5,7-dihydroxytryptamine intracerebral microinjected rats (5 microgram/400 nl into the fornix-fimbria and the cingulum bundle, 6 day survival) caused a dramatic decrease in these aggregates. The distribution of hippocampal 5-HT axons and terminals, inferred from the pattern of silver grain aggregates, is more widespread than previously described. 5-HT varicosities were clearly seen in all layers of Ammon's horn, dentate gyrus, and the subicular cortex. Innervation routes were seen to the stratum radiatum and stratum lacunosum from stratum oriens in Ammon's horn, and to the polymorphic layer of the dentate gyrus from the subicular cortex and from the fimbria. Semiquantitation of the occurrence of silver grain aggregates was done in the various hippocampal regions. The highest density in Ammon's horn was 119.5 boutons/10,000 micron2, in the dentate gyrus it was 67.4 boutons/10,000 micron2, and in the subicular cortex it was 79.2 boutons/10,000 micron2. These results are consistent with previous quantitative results.

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