Secretory, Motor and Vascular Effects in the Sublingual Gland of the Rat Caused by Autonomic Nerve Stimulation

Abstract

The influence of the autonomic nerves on sublingual glands of rats was studied. Stimulation of the chorda-lingual nerve evoked a lively flow of saliva and was also thought to contract the myoepithelial cells in the gland. Sympathetic nerve stimulation, on the other hand, usually evoked no secretion and did not cause any motor responses in the sublingual gland. The glandular blood flow was increased by chorda-lingual nerve stimulation, and this vasodilatation persisted also when atropine had been administered. Sympathetic nerve stimulation decreased the sublingual blood flow; this vasoconstrictor effect was mediated via activation of a-adrenoceptors.Rat salivary glands have been increasingly used to investigate the secretory mechanisms of water, electrolytes and organic substances in exocrine glands in vivo and in vitro [see Ohlin, 1966;Schneyer, Young and Schneyer, 1972;Young, 1973;Selinger, Eimerl, Savion and Schramm, 1974;Thulin, 1976]. The sublingual gland of the rat is considered to be a convenient system for comparative studies of secretion from serous and mucous cells since both cell types are present in the acini of this gland [Kim, Nasjleti and Han, 1972].The innervation pattern of the sublingual gland of the rat is well established morphologically. Thus, the autonomic nerve terminals which are present around the acini seem to be cholinergic and are in very close association with the parenchymal and myoepithelial cells [Snell and Garrett, 1957; Scott and Pease, 1959]. According to Norberg and Olson [1965] adrenergic nerve terminals are found only adjacent to the blood vessels and at a relatively long distance from the parenchymal and the myoepithelial cells, although it has been proposed that the mucous cells of the sublingual acini are sympathetically innervated [Fujiwara, Tanaka, Hattori and Honjo, 1966]. But no information is available concerning the influence of the autonomic nerves on different effector cells in the rat sublingual gland, although secretion elicited by different secretagogues such as methacholine, adrenaline and isoprenaline has been studied in this gland by Ohlin and Perec [1965]. Accordingly secretory and motor events in the sublingual gland resulting from nerve stimulation and the administration of drugs have now been studied. Observations on the glandular blood flow were also made. METHODSForty male Wistar rats (280-380 g), anaesthetized with chloralose (100 mg. kg-') administered via a cannulated femoral vein after induction with ether, were used. A tracheal tube was inserted. The sublingual duct was cannulated either on the right or on the left side with a glass 59

Differences in Morphology and Neuropeptide Immunoreactivity of Superior Cervical Ganglion Neurons that Innervate the Major Salivary Glands in Rats.

“…It is generally understood that the salivary secretion of the parotid gland (PG) which is composed almost entirely of serous acini and the submandibular gland (SMG) which is composed of a mixture of serous and mucous acini [31] are controlled by both the sympathetic and parasympathetic nervous systems, and secretion of the sublingual gland (SLG) which is composed of mainly mucous acini appears to be controlled by the parasympathetic nervous system alone [15,51,54]. However, the SLG is also innervated by the superior cervical ganglion (SCG) whose nerve fibers distribute around ducts or blood vessels and decrease blood flow in the SLG [48,52].…”

Communications

“…This contrasts with the marked difference in properties of junctional and extrajunctional acetylcholine receptor channels on frog muscle membrane (Neher & Sakmann, 1976 The discovery of atropine-resistant parasympathetic vasodilatation in the rat submandibular and major sublingual glands (Thulin, 1976, andTempleton &Thulin, 1978, respectively) coupled with the finding of perivascular fibres containing vasoactive intestinal peptide (VIP)-like immunoreactivity in the latter (Wharton, Polak, Bryant, Van Noorden, Bloom & Pearse, 1979) has prompted a detailed ultrastructural comparison of the perivascular nerves in both tissues.…”

The influence of estrogen and progesterone on parasympathetic vasodilatation in the rat submandibular gland

“…Although acetylcholine is the main neurotransmitter released from parasympathetic nerves in the submandibular gland, an atropine-resistant parasympathetic vasodilatation has been observed in several species including the cat (Lundberg et al 1981; Edwards and Garrett, 1993), ferret (Tobin et al 1991, 1997), pig (Modin et al 1994), rat (Darke and Smaje, 1972; Thulin, 1976; Templeton and Thulin, 1978; Anderson and Garrett, 1998). This atropine-resistant vasodilatation is due to the co-release of neuropeptides, such as vasoactive intestinal peptide (VIP) and substance P (Ekström, 1999), and in the rat submandibular gland both substances appear to play a role in this phenomenon (Anderson and Garrett, 1998).…”