Regulation of the concentration of adenosine 3',5'-cyclic monophosphate and the activity of tyrosine hydroxylase in the rat superior cervical ganglion by three neuropeptides of the secretin family

Abstract

Preganglionic nerve stimulation leads to an acute elevation of tyrosine hydroxylase (TH) activity in the rat superior cervical ganglion. This effect is mediated in part by acetylcholine, acting via nicotinic receptors, and in part by a noncholinergic neurotransmitter. As a first step in an attempt to identify this noncholinergic transmitter, we have examined a number of biogenic amines, purine nucleotides, neuropeptides, and other compounds for their ability to increase TH activity. Secretin, vasoactive intestinal peptide (VIP), and PHI (a 27-amino acid peptide with an NH2-terminal histidine and a COOH-terminal isoleucine amide), all members of the secretin family of peptides, increased TH activity acutely. Human pancreatic growth hormone-releasing factor, glucagon, and gastric inhibitory peptide (three other members of this peptide family) and all other transmitter candidates tested had no effect on this enzyme activity. We have examined the possibility that this peptidergic regulation of TH activity is mediated via changes in adenosine 3',5'-cyclic monophosphate (cAMP) levels. When the six members of the secretin family were tested for their ability to increase cAMP levels in the ganglion, secretin, VIP, and PHI significantly increased this cyclic nucleotide, whereas growth hormone-releasing factor, glucagon, and gastric inhibitory peptide produced no significant effects. The rank orders of potency and of efficacy of secretin, VIP, and PHI in altering TH activity and cAMP levels were identical. Furthermore, a strong correlation was found between the cAMP level and the TH activity in individual ganglia exposed to these peptides. Finally, 8-bromoadenosine 3',5'-cyclic monophosphate and forskolin also increased TH activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of Transepithelial lon Transport by Secretin in Human Intestinal Caco-2 Cells.

“…However, it has been reported that secretin also induces biological responses in several cells besides pancreatic cells [11][12][13]. The present study is the first to show that secretin stimulates ion transport and induces alkalinization of the apical solution in the monolayers of intestinal Caco-2 cells.…”

“…In pancreatic duct cells, secretin activates a Na ϩ -HCO 3 Ϫ cotransporter in the basolateral membrane [8, 9] and a small-conductance Cl Ϫ channel in the apical membrane [10] through the elevation of intracellular cAMP, which results in bicarbonate secretion across the apical membrane. In brain [11] and adrenal pheochromocytoma PC-12 cells [12], secretin activates tyrosine hydroxylase, which is the rate-limiting enzyme in the biosynthesis of catecholamines, suggesting that secretin may also work as a neuromodulator. Recently, it has been reported that secretin in-…”

Peptidergic modulation of the membrane potential of the Schwann cell of the squid giant nerve fibre.

“…In many preparations VIP is thought to bring about its effects by increasing intracellular levels of cyclic AMP (Rougon et al 1983;Etgen & Browning, 1983;Evans et al 1984;Magistretti & Schorderet, 1984;Ip, Baldwin & Zigmond, 1985). In the present study the effects of VIP were not potentiated by either theophylline or forskolin at concentrations where they potentiate the effects of both carbachol (Evans et al 1985) and DL-octopamine (Reale et al 1986).…”

Phenotypic plasticity in adult sympathetic neurons: changes in neuropeptide expression in organ culture.

“…VIP produces a variety ofeffects on the rat SCG. For example, in adult neuronal cell bodies/dendrites, VIP increases levels of cAMP (19,34) and inositol phosphate (35), increases the activity and extent of phosphorylation of tyrosine hydroxylase (19,36), enhances synaptic transmission in the ganglion (37), and potentiates the electrophysiological response to muscarinic agonists (38). In those systems where PHI has also been examined, it produces effects similar to those of VIP, with the exception of the increase in inositol phosphate (35).…”