Alvarez Alvarado Ramón, Porras Villalobos Mercedes Graciela, Calderón Rosete Gabina, Rodríguez Sosa Leonardo, Aréchiga Hugo
División de Estudios de Posgrado e Investigación, Facultad de Medicina, UNAM. ler. Piso Unidad de Posgrado, Ciudad Universitaria, México.
Cell Mol Neurobiol. 2005 Mar;25(2):345-70. doi: 10.1007/s10571-005-3064-9.
The main aims of this paper are (a) to locate possible dopaminergic neurons in the eyestalk with anti-tyrosine hydroxylase antibodies, (b) to search for the presence of dopamine (DA) in the nervous structures of the eyestalk, (c) to explore its release, and (d) to test the effect of DA on neurosecretory cells in the eyestalk. Experiments were performed in adult crayfishes Procambarus clarkii, in isolated optic peduncle. Immunocytochemistry was made with the antibody against its precursor synthesizing enzyme tyrosine-hydroxylase. The content and release studies of DA were made using high performance liquid chromatography (HPLC). Extracellular and intracellular recordings were conducted with conventional recording techniques. A large number (approximately 2000) of immunopositive somata of different sizes and shapes were identified in various regions of the eyestalk. The majority of somata are of the smallest size (5-25 microm diameter). DA content in the eyestalk was 5.6 +/- 0.1 pmol per structure; the greatest content is in the MT (over 60%). A basal level release of DA was observed. Incubation of eyestalks in solution containing a high K+ concentration increased the DA release (79%). Two effects of DA on the excitability of X-organ neurons were observed; an excitatory effect on neurons of approximately 25 microm somata diameter and another inhibitory effect in the group of approximately 35-microm somata diameter neurons. The excitation occurs with a depolarization and decrement of membrane conductance in the cell soma while the inhibition occurs with a hyperpolarization and increment of membrane conductance in soma. We concluded the following: (1) Dopamine is present in each optic ganglia of the crayfish eyestalk. (2) There is a basal release of DA from the isolated eyestalk. (3) DA release is enhanced threefold by eyestalk incubation in 40 mM [K+] solution. (4) DA selectively excites a population of neurons with low-speed conduction axons, and small somata in the X-organ-sinus gland system, while inhibiting another population characterized by higher axonal conduction speed and large somata. (5) These observations support a role for DA as a neurotransmitter or neuromodulator in the X-organ neurons of the crayfish eyestalk.
（a）用抗酪氨酸羟化酶抗体定位眼柄中可能存在的多巴胺能神经元；（b）探寻眼柄神经结构中多巴胺（DA）的存在情况；（c）探究其释放情况；（d）测试DA对眼柄中神经分泌细胞的作用。实验在成年克氏原螯虾的离体视神经节上进行。采用针对其前体合成酶酪氨酸羟化酶的抗体进行免疫细胞化学实验。使用高效液相色谱法（HPLC）进行DA的含量和释放研究。运用传统记录技术进行细胞外和细胞内记录。在眼柄的不同区域鉴定出大量（约2000个）大小和形状各异的免疫阳性细胞体。大多数细胞体尺寸最小（直径5 - 25微米）。眼柄中DA的含量为每个结构5.6±0.1皮摩尔；含量最高的是中脑（超过60%）。观察到DA有基础水平的释放。将眼柄置于高钾浓度溶液中孵育可增加DA的释放（79%）。观察到DA对X器官神经元兴奋性有两种作用；对直径约25微米的细胞体的神经元有兴奋作用，对直径约35微米的细胞体的神经元群体有抑制作用。兴奋表现为细胞体去极化和膜电导降低，而抑制表现为细胞体超极化和膜电导增加。我们得出以下结论：（1）多巴胺存在于克氏原螯虾眼柄的每个视神经节中。（2）离体眼柄有DA的基础释放。（3）将眼柄置于40 mM [K⁺]溶液中孵育可使DA释放增加三倍。（4）DA选择性地兴奋X器官 - 窦腺系统中轴突传导速度慢、细胞体小的神经元群体，同时抑制另一群体，其特征是轴突传导速度较高且细胞体较大。（5）这些观察结果支持DA在克氏原螯虾眼柄X器官神经元中作为神经递质或神经调节剂的作用。
