Thyrotropin-like immunoreactivity in human retina: immunoreactive co-localization in ganglion cells and perivascular fibers.
The present immunocytochemical study has demonstrated immunoreactive thyrotropin-like ganglion cell populations as well as perivascular fibers in the human retina by using specific antiserum. Thyrotropin is a pituitary glycopeptide involved in the synthesis and release of thyroid hormones. The existence and functions of peptides in vertebrate retinas are still not well known. Many authors have reported neuropeptide immunoreactivity in the human retina which have had their functions established in the neuroregulatory processes of vision. Moreover, some authors have reported the possibility that the fiber terminal of peptidergic neurons may also be a blood vessel. The appearance of immunoreactive-cells in human retina, e.g. existence of retinal ganglion cells with thyrotropin-like immunoreactivity, indicates the existence of specific mechanisms that would be mediated by these peptides which are located near immunoreactive ganglion cells. We hypothesize that there is an intrinsic mechanism for blood flow control, mediated by retinal ganglion cells which may regulate vessel diameter according to its luminous stimuli. No-one has demonstrated the presence or the functional existence of thyrotropin-like immunoreactive structures in the vertebrate retina, or on the side of the pituitary-thyroid axis. To the best of our knowledge this is the first time that thyrotropin has been immunocytochemically demonstrated in the human retina. Thus, we suggest that thyrotropin acts as a neuromodulator in the human retina, which is implicated in blood flow control.
Fernández-Trujillo
F J
FJ
Dept. of Morphological Sciences, Faculty of Medicine, University of Cádiz, Spain.
Prada
A
A
Verástegui
C
C
D000818:Animals; D000906:Antibodies; D006801:Humans; D007150:Immunohistochemistry; D009412:Nerve Fibers / Q000648:ultrastructure*; D011817:Rabbits; D012160:Retina / Q000737:chemistry / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000737:chemistry / Q000166:cytology*; D012171:Retinal Vessels / Q000294:innervation*; D013972:Thyrotropin / Q000032:analysis*
D000906:Antibodies; D013972:Thyrotropin