Abstract
Purpose: :
It has recently been shown that nicotinic acetylcholine receptors are present also in non-neuronal tissue and that they together with SLURP (secreted mammalian Ly-6/urokinase plasminogen acivator receptor-related protein) might be involved in immuno-modulatory/apoptotic events. The aim of the present study is therefore to investigate the presence of the alpha-7 subunit of the nicotinic acetylcholine receptor and SLURP in the rabbit lacrimal gland.
Methods: :
Rabbit lacrimal gland acinar cells were prepared according to our standard procedure (Gierow et al., Am. J. Physiol. (Cell Physiology) 271: C1685, 1996; Andersson et al, Glycobiol. 15: 211, 2005) yielding single cells that were placed in a serum-free culture medium on standard culture plates coated with Matrigel for two days. The cultured cells were rinsed briefly and secretion was measured after a pre-incubation for 30 min at 37 C, with buffer alone, followed by incubation for an additional 30 min w./w.o. secretagogues as indicated. Basal secretion and regulated secretion was determined enzymatically as secreted beta-hexosaminidase activity. The lacrimal gland was also subjected to immunohistochemistry to confirm the presence the alpha-7 subunit, SLURP-1 and -2.
Results: :
Secretion of beta-hexosaminidase from cultured acinar cells was significantly increased by approximately 30 %, at 1 µM nicotine. Immunohistochemistry indicated that both the alpha-7 subunit of the nicotinic acetylcholine receptor and its ligand SLURP-1 are present in lacrimal tissue, whereas SLURP-2 could not be detected.
Conclusions: :
Our results indicate that both the alpha-7 subunit of the nicotinic acetylcholine receptor and its ligand SLURP-1 are present in the rabbit lacrimal gland and that nicotine tartrate has stimulatory effects on protein secretion in cultured cells.
Keywords: lacrimal gland • neurotransmitters/neurotransmitter systems • receptors