Peptidergic nerves in the eye, their source and potential pathophysiological relevance

Distribution of galanin receptors in the human eye

“…However, in various different mammals GAL is also widely distributed within other parts of the cranial autonomic nervous system (Troger et al, 2007), and known species differences in neuropeptide distribution easily contribute to these contrary observations. Nevertheless, GAL has been also detected in human aqueous humor (Ortego and CocaPrados, 1998), and further in human ciliary epithelium in-vitro (Ortego and Coca-Prados, 1998) indicating that other ocular sources of GAL exist besides the autonomic nervous system.…”

“…This control is maintained, besides known local mechanisms, for the most part by the autonomic nervous system (McDougal and Gamlin, 2015;Neuhuber and Schrodl, 2011). While autonomic control utilizes well investigated classical transmitters for signal transduction, such as acetylcholine or norepinephrine, a plethora of neuropeptides is additionally involved in these mechanisms, mainly for signal-modulation (Troger et al, 2007). In many instances, however, the exact mechanisms of signal transduction/-modulation are not understood yet.…”

Changes in Corneal Subbasal Nerve Morphology and Sensitivity During Orthokeratology: Onset of Change

“…Corneal nerves also play an important trophic role in epithelial cell growth, wound healing, and repair through the release of specific neuropeptides and neurotransmitters. [1][2][3][4] The subbasal nerve plexus (SBNP) is a nerve fiber layer that is located beneath the corneal epithelium and detected relatively easily using in vivo laser-scanning confocal microscopy. Consequently, it is a common subject for evaluation when investigating the impact of ocular and systemic diseases on corneal innervation, such as in dry eye, 5 infectious keratitis, 6 and keratoconus.…”

Bright light activates a trigeminal nociceptive pathway

“…Although many intraocular trigeminal nerve fibers contain calcitonin gene-related peptide, a neuropeptide associated with peripheral nociceptors [44,52] and light sensitivity in animals [40], their function remains uncertain. Intraocular trigeminal nerves encode changes in ocular perfusion pressure, temperature and intraocular pressure [33,57] and are thought to serve mainly ocular homeostatic functions [47,53]. The notion that intraocular sensory nerves also mediate non-visual sensations has not been adequately tested.…”