title: Reduced methacholine-induced submandibular salivary secretion in rats with experimental periodontitis.
abstract: OBJECTIVE
  Saliva is the first barrier to the entry of bacteria and viruses into the body and is considered a necessary instrument in oral health. Intraperitoneal injection of lipopolysaccharide endotoxins results in submandibular gland (SMG) hyposalivation. The objective of present studies was to assess if periodontitis, a chronic inflammatory disease caused by oral bacteria, alters cholinergic-induced SMG salivary secretion.
  
  
  METHODS
  An experimental periodontitis model (EP) (cotton thread ligature around the neck of the first lower molars) was used. Male Wistar rats (300-380g) were randomly divided into 3 groups: control, 7 days-bilateral EP and 7 days-unilateral EP (to study if there were different effects at the ipsilateral and contralateral side). The following determinations were performed in SMG: (1) dose-response curves to the cholinergic agonist methacholine, (2) prostaglandin E (PGE) content, (3) inducible nitric oxide synthase (iNOS) activity and (4) histology of gland sections.
  
  
  RESULTS
  The molars with EP, no matter the group, exhibited significant and similar bone loss (p<0.001). Bilateral EP reduced methacholine-induced salivary secretion (p<0.05, dose 1μg/kg; p<0.001, dose 3-30μg/kg), increased PGE content (p<0.01), stimulated iNOS activity (p<0.05). Ipsilateral glands of unilateral EP animals presented lower methacholine-induced salivary secretion (p<0.05, dose 3μg/kg; p<0.001, dose 10-30μg/kg), and higher PGE content than contralaterals (p<0.001). In turn, at 3 and 10μg/kg of methacholine, contralateral glands showed significantly lower secretion than control animals (p<0.001). Histological studies of glands revealed partial loss of secretor granular material and periductal oedema in the bilateral and unilateral EP groups as compared to controls.
  
  
  CONCLUSIONS
  As far as we know, the present results demonstrate for the first time that EP reduces methacholine-induced SMG salivary secretion.
authors.affiliation: Cátedra de Anatomía, Facultad de Odontología, Universidad de Buenos Aires, Argentina.
authors.forename: Mariano
authors.initials: M
authors.lastname: Amer
authors.forename: Juan C
authors.initials: JC
authors.lastname: Elverdin
authors.forename: Javier
authors.initials: J
authors.lastname: Fernández-Solari
authors.forename: Vanina A
authors.initials: VA
authors.lastname: Medina
authors.forename: Ana P
authors.initials: AP
authors.lastname: Chiarenza
authors.forename: María I
authors.initials: MI
authors.lastname: Vacas
mesh_terms: D000818:Animals; D015232:Dinoprostone / Q000032:analysis; D004195:Disease Models, Animal; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D052247:Nitric Oxide Synthase Type II / Q000032:analysis; D010518:Periodontitis / Q000150:complications*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012463:Saliva / Q000187:drug effects / Q000378:metabolism*; D012472:Salivation / Q000187:drug effects*; D013363:Submandibular Gland / Q000187:drug effects* / Q000378:metabolism
chemical_list: D016210:Methacholine Chloride; D052247:Nitric Oxide Synthase Type II; D015232:Dinoprostone