Maxadilan interacts with receptors for pituitary adenylyl cyclase activating peptide in human SH-SY5Y and SK-N-MC neuroblastoma cells.

Receptors for pituitary adenylyl cyclase activating peptide (PACAP) have been identified in human SH-SY5Y neuroblastoma cells with PACAP being 1000-fold more potent than vasoactive intestinal peptide (VIP) in [(125)I]PACAP binding inhibition and stimulation of cAMP accumulation. Maxadilan, a vasodilator peptide from the salivary gland of the sand fly Lutzomyia longipalpis also specifically bound to SH-SY5Y cells, and was equipotent to PACAP in [(125)I]PACAP and [(125)I]maxadilan binding inhibition, and stimulation of cAMP accumulation. Maxadilan and PACAP also increased the cytosolic free calcium concentration. In human SK-N-MC neuroblastoma cells PACAP, VIP and maxadilan equipotently stimulated cAMP accumulation. The maximal effects of VIP and maxadilan were additive and reached those of PACAP alone. In human T47D breast carcinoma cells PACAP and VIP were also equipotent in the stimulation of cAMP accumulation, but maxadilan was inactive. The results are consistent with the interaction of maxadilan with PACAP specific PAC(1)receptors in SH-SY5Y cells, but not with VPAC receptors, not differentiating between VIP and PACAP in T47D cells. Moreover, maxadilan is a PAC(1)receptor specific agonist which allows discrimination of co-expressed PAC(1)and VPAC receptors in SK-N-MC cells.

Differential expression of calcitonin and parathyroid hormone/parathyroid hormone-related protein receptors in P19 embryonic carcinoma cells treated with retinoic acid.

Mouse embryonic carcinoma P19 cell aggregates treated with retinoic acid (RA) sequentially differentiate into neurons and astrocytes, whereas attached cells develop a mesodermal phenotype. The expression of calcitonin (CT) and PTH/PTH-related protein (PTHrP) receptors was investigated in embryonic cells, and during neural and mesodermal differentiation. In embryonic P19 cells, specific binding of [125I]salmon (s) CT(1-32) ([125I]sCT(1-32)) was 56 fmol/mg protein, and of [125I]chicken (ch) [Tyr36]PTHrP(1-36) amide ([125I]chPTHrP(1-36)) < 0.5 fmol/mg protein. Correspondingly, cAMP was maximally stimulated 47-fold by sCT(1-32) (EC50 0.05 nM) and 3-fold by chPTHrP(1-36) (EC50 1.3 nM). Receptor autoradiography revealed specific binding of [125I]sCT(1-32) to the undifferentiated P19 cells, but not to RA induced neurons and astrocytes. At the same time, [125I]sCT(1-32) binding and cAMP accumulation by sCT were gradually decreased. But, specific binding of [125I]chPTHrP(1-36) was raised at least 6-fold compared with embryonic cells to 3 fmol/mg protein, in parallel with a 10-fold higher maximal cAMP accumulation. A similar, but delayed suppression of CT and stimulation of PTH/PTHrP receptor expression was observed during mesodermal cell differentiation. The results indicate that CT receptors are associated with undifferentiated P19 cells, whereas PTH/PTHrP receptors are expressed in RA induced neural and mesodermal cells.

Structure of a parathyroid hormone/parathyroid hormone-related peptide receptor of the human cerebellum and functional expression in human neuroblastoma SK-N-MC cells.

Cloning and functional expression of a cDNA from the human cerebellum revealed a parathyroid hormone/parathyroid hormone-related peptide (PTH/PTHrP) receptor protein of 593 amino acids, identical in sequence to the PTH/PTHrP receptor of the human kidney and an osteoblast-like cell line (Schipani et al., Endocrinology, 132 (1993) 2157-2165). Expression of mRNA hybridizing with the cloned cDNA, indistinguishable in size on Northern blots from a 2.3 kb transcript in kidney and liver, was detected in eight brain areas. In situ hybridization histochemistry in rat brain tissue sections revealed predominant signals in the Purkinje cell layer of the cerebellum and in the mesencephalic nucleus of the trigeminal nerve. In human neuroblastoma (SK-N-MC) cells, stably transfected with the cloned cDNA, hPTH(1-84) and hPTH(1-34) displaced binding of 125 pM [125I][Tyr36]chPTHrP(1-36) to the PTH/PTHrP receptor with IC50 values of 4.0 +/- 0.6 nM and 2.00 +/- 0.08 nM, and stimulated cyclic AMP accumulation with EC50 values of 0.19 +/- 0.06 nM and 0.09 +/- 0.01 nM, respectively. 16 out of 48 cells responded to 100 nM hPTH(1-34) with a 2-10-fold transient increase of cytosolic free calcium concentrations. In conclusion, a PTH/PTHrP receptor, identified in the human cerebellum, has the primary structure of the corresponding receptors of kidney and bone. Expression in human neuroblastoma SK-N-MC cells revealed functional properties indistinguishable from those of non-neuronal tissues. The widespread distribution of PTHrP and its receptor in brain implies biological functions remaining to be elucidated.

[Hypertension, Type II diabetes mellitus and macroangiopathy: risk factors and their association]. / Hypertonie, Diabetes mellitus Typ II und Makroangiopathie: Risikofaktoren und ihre Assoziationen.

In this review the independent risk factors of hypertension, diabetes mellitus type II and large vessel disease are discussed. Hyperinsulinemia as the most important factor is associated with obesity, dyslipoproteinemia, alcohol drinking, physical inactivity, hyperfibrinogenemia, smoking (among men), microalbuminuria and hyperuricemia, which are sometimes partially related. If one factor occurs, the other associated factors have to be searched for in order to initiate an adequate treatment. To improve the acceptance of adequate advice, the knowledge of risk reduction should influence the health education.