Study On Morphology And The Distribution Of GABA In Cerebellum Of Ostrich

Cerebellum is a senior center for regulating somatic movement which plays main roles in maintaining muscle tension, keeping balance and coordinating voluntary movement. Additionally, cerebellum has something to do with learning, memory and cardiovascular activities.γ-Aminobutyric acide (GABA) is one kind of non-protein natural amino acids and is the most important inhibitory neurotransmitter in central nervous system. Additionally, GABA has many physiological functions, such as lowering blood pressure, improvement of brain function, anticonvulsion, prevention and treatment of epilepsy, activation of liver and kidney and promotion of sperm fertilization. The Purkinje cells are the only efferent fiber in the cerebellar cortex and their neurotransmitter is GABA. Meanwhile, as a important inhibitory neurotransmitter in the central nervous system, GABA takes a part in 40% nerve-mediated inhibitory and has an impact on many physiological activities.Lots of researches were carried out about GABA existing in mammals. Although a spot of datum were engaged in about GABA existing in birds, whether GABA was existing in ostrich or its structure or role was different between other animals, has not reported. African ostrich chicks were used as experimental animals whose cerebellums were carrying on morphological study. The HE staining, Nissl staining and SABC immunohistochemical method were used to investigate the distribution of GABA-immunoreactive cells in ostrich chicks of different ages and the comparison on distribution of GABA-immunoreactive cells between ostrich and other fowls. The main contents and research results were as followed:1 Morphological study on cerebellum of African ostrich chicksIn order to prove up the morphological structure, six African ostriches were used in the present study. These animals were deeply anaesthetized with 20% urethane at a dose of 1g/kg BW. Then the cerebellums were obtained after craniotomy and slices were cut by a microtome after fixed fully. The location, form and cytoarchitecture of cerebellum nerve nuclei were observed under the bright light microscope. The results showed that the missing middle-shaped cross-section of cerebellum in ostriches was elliptical approximation and its delamination was similar to that of Pekin Duck, silky fowl and pigeon. The cerebellar cortex was separated as molecular layer, Purkinje cell layer and granular layer from the outer to the inner. The molecular layer was situated at superficial layer in cortex and contained less neurons. Purkinje cell layer composed of large soma of Purkinje cells with regular arrangement was located in the deep molecular cortex. The cells were taking on pyriform, round or ellipse whose diameter was 27.5-37.5μm. The granular layer was situated at the deepest cerebellar cortex, consisted of intensive arrangement granular cells and less Golgi cells. It is found that the cytoarchitecture of necleus cerebellaris medialis was similar to that of Pekin duck and pigeon. But there were a large number of neurons in the necleus cerebellaris medialis and the cells were arranged loosely. Additionally, its longest to strocaudal axis was longer than that of Pekin duck. The results indicated that the necleus cerebellaris medialis was fully developed.2 Study on the development of cerebellum and age related changes about GABA expressingIn order to prove up the distribution of GABA-immunoreactive neurons in the cerebellum, neonatal days 1, 45, 90, and 334 female African ostriches were used in the present study. The structure of the cerebellar cortex was displayed by Nissl staining and GABA-immunoreactive neurons were marked by SABC immunohistochemical method. The results showed that the soma, main dendritic, nucleus, and theirs nucleolus were very clear. Nissl bodies were royal purple or powder blue and taken on fine granular and accumulating with plaque. The size of cells was different. The GABA-immunoreactive neurons, fibers and positive spots were found at all the layers of the cerebellar cortex in the ostrich chicks of different ages. Immunoreactivity was taken on claybank and tawny color. The GABA immunoreactive neurons in the 45-day ostrich chicks was stronger than that of other stages. These results indicated that GABA was synthetized reaching a maximum. It was speculated that the 45-day was a critical period throughout the rearing phase and could be able to reach the peak of growing development of ostrich chicks. 3 Distribution of the GABA-immunoreactive neurons in the cerebellum of African ostrichIn order to investigate the location and distribution of GABA-immunoreactive neurons in the cerebellum at different animals, the healthy African ostriches, Sanhuang chickens and Wanxi white geese were used through SABC immunohistochemical method marking GABA-immunoreactive neurons, and each animal was six. The results showed that the GABA-immunoreactive neurons, fibers and positive spots were found at all the layers of the cerebellar cortex. Immunoreactivity was brown and blue and taken on kernel and globular. The different intension of GABA-immunoreactive products was appeared in parts of neurons. The minority of them had immunoreactive fibers and endings. GABA-immunoreactive neurons not only located at stellate cells, basket cells, Purkinje cells, Golgi cells and necleus cerebellaris medialis, but also situated at all the layers of cerebellum of Sanhuang chicken and Wanxi white goose. Additionally, GABA-immunoreactive neurons of the three layers in African ostrich was obviously higher than that of the Sanhuang chicken and Wanxi white goose. These results showed that there were lots of GABA synthetized from Purkinje cells and GABA might participated in activities concerned of cerebellar central nucleus to regulated many meticulous functions in cerebellum.