Badlangana N Ludo, Bhagwandin Adhil, Fuxe Kjell, Manger Paul R
School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, Republic of South Africa.
J Chem Neuroanat. 2007 Nov;34(3-4):69-79. doi: 10.1016/j.jchemneu.2007.05.003. Epub 2007 May 22.
The current study details the nuclear parcellation and appearance of putative catecholaminergic and serotonergic neurons within the medulla oblongata of a sub-adult giraffe, using immunohistochemistry for tyrosine hydroxylase and serotonin. We hypothesized that the unusual phenotype of the giraffe, this being the long neck and potential axonal lengthening of these neurons, may pose specific problems in terms of the efficient functioning of these systems, as several groups of catecholaminergic and serotonergic neurons, especially of the medulla, are known to project to the entire spinal cord. This specific challenge may lead to observable differences in the nuclear parcellation and morphology of these systems in the giraffe. Our personal observations in the giraffe reveal that, as with other Artiodactyls, the spinal cord extends to the caudal end of the sacral vertebrae. Within the giraffe medulla we found evidence for five putative catecholaminergic (neurons containing tyrosine hydroxylase) and five serotonergic nuclei. In terms of both morphological appearance of the neurons and nuclear parcellation we did not find any evidence for features that may be considered affected by the phenotype of the giraffe. The nuclear parcellation and appearance of both the putative catecholaminergic and serotonergic systems in the medulla of the giraffe studied are strikingly similar to that seen in previous studies of other Artiodactyls. We interpret these findings in terms of a growing literature detailing order specific phylogenetic constraints in the evolution of these neuromodulatory systems.
本研究利用酪氨酸羟化酶和血清素的免疫组织化学方法，详细描述了亚成年长颈鹿延髓内假定的儿茶酚胺能和血清素能神经元的核分割及外观。我们推测，长颈鹿独特的表型，即长脖子以及这些神经元可能存在的轴突延长，可能会给这些系统的有效运作带来特定问题，因为已知几组儿茶酚胺能和血清素能神经元，尤其是延髓中的神经元，会投射到整个脊髓。这种特殊挑战可能导致长颈鹿这些系统在核分割和形态上出现可观察到的差异。我们对长颈鹿的个人观察表明，与其他偶蹄目动物一样，脊髓延伸至骶椎的尾端。在长颈鹿的延髓内，我们发现了五个假定的儿茶酚胺能（含酪氨酸羟化酶的神经元）和五个血清素能核团的证据。就神经元的形态外观和核分割而言，我们没有发现任何可能受长颈鹿表型影响的特征证据。所研究的长颈鹿延髓中假定的儿茶酚胺能和血清素能系统的核分割及外观，与之前对其他偶蹄目动物的研究结果惊人地相似。我们根据越来越多详细描述这些神经调节系统进化中特定系统发育限制顺序的文献来解释这些发现。
