ABSTRACT
The distribution of somatostatin (SRIF) in substantia gelatinosa of the rat spinal cord was studied by means of immuno-electron microscopy. The ultrastructural features showed that nerve terminals containing SRIF take part in forming presynap- tie elements of axe-somatic, axe-dendritic and axo-axonic synapses. The immune- reactive products locatl at the external membrane of mitochondria, around the small clear synaptie vesicles and in the large granular vesicles. Most of synaptic vesicles are round or ovoid in shape. Only a few of them are flattened. Based on the ultrastructural characteristics mentioned above and related experimental results the authors believe that SRIF in substantia gelatinosa of the rat spinal cord is probably involved as a neurotransmitter instead of neuromodulator.
ABSTRACT
Using the immunohistochemical and immunoelectron microscopic methods, the localization and pattern of vasoactive intestinal polypeptidergic nerves in the wall of cerebral vessels were investigated. The results revealed that the VIP-like immunoreactive (VIPLI) fibres were located in the adventitia or at the adventitia-media border. No synaptic contacts were identified among the nerve terminals or between nerve terminal and smooth muscle cell. VIPLI terminals directly apposed to the smooth muscle cells with a distance of 100 nm.The observations mentioned above indicate that there is peptidergic innervation in the wall of the cerebral vessels besides traditional adrenergic and cholinergic innervations. The regulatory function of VIP-containing nerves to the cerebral vessels may be performed by affecting the smooth muscle directly through the nonsynaptic release. In addition, present study identified and discussed the distribution and function of substance P(SP) in the cerebral vessels.