ABSTRACT
The hippocampus makes new memories and is involved in mental cognition, and the hippocampal dentate gyrus (DG) is critical because neurogenesis, which occurs throughout life, occurs in the DG. We observed the differentiation of neuroblasts into mature neurons (granule cells) in the DG of C57BL/6 mice at various early postnatal (P) ages: P1, P7, P14, and P21 using doublecortin (DCX) immunohistochemistry (IHC) for neuroblasts and calbindin D-28k (CB) IHC for granule cells. DCX-positive cells decreased in the DG with age; however, CB+ cells increased over time. At P1, DCX and CB double-labeled (DCX+CB+) cells were scattered throughout the DG. At P7, DCX+CB+ cells (about 92% of CB+ cells) were seen only in the granule cell layer (GCL) of the dorsal blade. At P14, DCX+CB+ cells (about 66% of CB+ cells) were found in the lower half of the GCL of both blades. In contrast, at P21, about 18% of CB+ cells were DCX+CB+ cells, and they were mainly located only in the subgranular zone of the DG. These results suggest that the developmental pattern of DCX+CB+ cells changes with time in the early postnatal stages.
Subject(s)
Animals , Mice , S100 Calcium Binding Protein G , Cognition , Dentate Gyrus , Hippocampus , Immunohistochemistry , Neurogenesis , NeuronsABSTRACT
The relationships between cholinergic neurons and SP terminals were examined in the rat sacral ventral horn at the light and electron microscopic levels by means of double immunostaining methods. Cholinergic neurons were labeled by a monoclonal antibody to choline acetyltransferase (CHAT) with the avidin-biotin technique and stained bluish-green by indolyl-?-galactoside reaction products with ?-galactosidase as a marker. On the same sections, SP fibers were labeled by polyclonal antisera to SP after application of the peroxidase-antiperoxidase (PAP) method and stained brown by diaminobenzidine (DAB)reaction. At the light microscopic level CHAT-I neurons stained bluish-green and SP- I fibers Stained brown were found in the ventral horn. At the electron microscopic level, many asymmetrical axodendritic synapses(type I of Gray)were observed between CHAT-I dendrites and SP-I terminals in the ventral horn, but axosomatic synapses and symmetrical synapses (type I of Gray) were hardly detected. These results indicate that SP-I terminals make direct synapses with CHAT-I motoneurons of sacral ventral horn. These synapses may be predominantly excitatory and have importance in the control of muscular constriction.
ABSTRACT
Objective To explore the relationship between dopaminergic axon terminal and GABAergic neurons and explore the neuroanatomic mechanism of their effects in schizophrenia. Methods The co-location and the association of dopaminergic axon terminal and GABAergic neurons in the basolateral nucleus (BL) of rat amygdala were examined by using double labeling immunoelectron microscopic techniques. Dopaminergic axon terminal and GABAergic neurons were labeled with the antidopamine (anti-DA) and the anti-glutamic acid decarboxylase (anti-GAD) antibodies respectively. Results 43% of the DA-input synapses was observed to relate directly or indirectly to GAD-immunoreactive(IR) dendritic structures(DA/GAD), which includes single (38%), convergent (30%), serial (20%), and axoaxonic (12%) contact types.And 57% of the DA-input synapses was found to associate with unlabeled elements (DA/UE), which includes unlabeled perikarya (10%), dendrites (82%) and axons (8%). All of the synapses that show DA-IR terminals profiles were found to be symmetric (inhibitory) synapses.Conclusion These results suggest that the dopaminergic system in the BL of rat amygdala controls the mediations of the GABAergic interneurons via symmetric synapses. In addition, the dopaminergic axon terminal associates with the glutamatergic projection neurons and exerts influence on its activity.