Relationships between neuronal cell adhesion molecule and LHRH neurons in the urodele brain: a developmental immunohistochemical study.
Polysialic acid (PSA), a homopolymer attached to neural cell adhesion molecule (NCAM) is considered a major hallmark of vertebrate cell migration. We studied the distribution of PSA-NCAM by immunohistochemistry, during brain development, in two urodele amphibians, Pleurodeles waltl and the neotenic newt Ambystoma mexicanum. In both species a gradual increase of immunolabelling was observed throughout the brain from developmental stage 30 to stage 52. At the onset of metamorphosis, some differences became evident: in Pleurodeles immunostaining was gradually restricted to the olfactory system while in Ambystoma, PSA-NCAM maintained a more extended distribution (for example throughout the telencephalic walls) suggesting, for the brain of this latter species, a rather preserved neuronal plasticity. The aim of the present work was to correlate the above described PSA-NCAM-immunoreactivity (IR) with the distribution of luteinizing hormone-releasing hormone (LH-RH) containing neurons, which represent a well known example of neural elements migrating from the olfactory placode. LHRH-IR, undetectable till stage 30, was later found together with PSA-NCAM-IR in both the olfactory system and septo-hypothalamic areas. Such observations further support a role of PSA in providing a migration route toward the establishment of a part, at least, of the urodele LHRH system. The possible functional meaning of the LHRH-containing neurons localized between dorsal and ventral thalamus of Ambystoma, never reported before in this area, almost devoid of PSA-NCAM-IR, is discussed.
Gianola
S
S
Dipartimento di Biologia Animale e dell'Uomo, Università degli Studi di Torino, Italy.
Clairambault
P
P
Franzoni
M F
MF
D000558:Ambystoma mexicanum; D000818:Animals; D001923:Brain Chemistry; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis / Q000378:metabolism*; D007124:Immunoenzyme Techniques / Q000379:methods; D019006:Neural Cell Adhesion Molecules / Q000032:analysis / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry / Q000378:metabolism*; D010999:Pleurodeles; D012794:Sialic Acids / Q000032:analysis / Q000378:metabolism*; D013788:Thalamus / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D014018:Tissue Distribution; D014562:Caudata / Q000502:physiology*
D019006:Neural Cell Adhesion Molecules; D012794:Sialic Acids; C021319:polysialic acid; D007987:Gonadotropin-Releasing Hormone