<b>RECEPTORS FOR VASOACTIVE INTESTINAL POLYPEPTIDE ON RAT DISPERSED PINEAL </b><b>CELLS </b>

Abstract

The receptor for vasoactive intestinal polypeptide (VIP) was characterized using rat dispersed pineal cells. 1251-VIP binding to the cells was saturable, reversible, and temperature-dependent. Scatchard analysis of "SI-VIP binding indicated the presence of two classes of binding sites: a. high aflinity-low capacity site and a low affinityhigh capacity site. Each cell possessed 42,000 high aflinity binding sites with a dissociation constant (Kd) of 0.8 >< l0'9M, and 780,000 low afiinity binding sites with a K, of 32>< l0"9M, respectively. Norepinephrine did not inhibit 1251-VIP binding to the pineal cells. 1251-VIP binding was displaced by natural secretin with 1/ l00 the potency of unlabeled VIP. The potency of displacement of C-terminal and Nterminal fragments was lower than that of natural secretin. VIP stimulated cyclic AMP production of the pineal cells with dose-dependency. Half-maximal stimulation was detected at a concentration of l0'9M. This stimulatory efiect closely corresponded with the manner of binding by VIP to the pineal cells. These results clearly demonstrate that the functions of the pineal gland are regulated through a. dual (,8-adrenergic and VIPergic) control system.

Presence of Vasoactive Intestinal Peptide Receptor in the Hen Hypothalamus.

“…[8], where the VIP receptor has a single class of binding sites with a Kd of 1.0 nM, and also on the cat renal outer medulla membrane [17] or the chicken pineal membrane [18] in which the binding site is a single class with a Kd of 0.83 nM or 0.98 nM. The results are different, however, from those obtained by similar competitive binding studies on guinea pig [7] and rat [9] brain, turkey [19] and rat [20] pituitary, rat pineal [21], rat uterus [22], feline kidney [17], chicken thymus and bursa of fabricius [23], and rat blood vessels [11]. In these tissues, the binding component possesses two distinct binding sites of low and high affinity.…”

A Vasoactive Intestinal Peptide Binding Component in Hen Granulosa Cells

“…A difference in the property of VIP receptor between animals and between tissues seems to exist. The B,,, value obtained in the present study is of a similar order to that reported on the hen pituitary (15) and hypothalamus (16), and on the highaffinity binding component in various VIP-responsive tissues of mammals (25,(27)(28)(29)(30)(31).…”

Vasoactive intestinal peptide stimulates melatonin release from perifused pineal glands of rats

“…The fact that the response was not completely inhibited by the antagonist to VIP receptors is probably explained by the low specificity of this antagonist which should have been used at higher concentrations. The physiological results obtained fit very well in with previous autoradiographic studies which revealed the presence of two classes (low affinity--high capacity and high affinity--low capacity) of VIPergic receptors on pinealocytes (Besson et al 1986;Kaku et al, 1983;Moller et al, 1984;Mikkelsen et al, 1987). The VIP receptors were found to be linked to adenylate cyclase (Taylor and Pert, 1979;Gespach et al, 1988).…”

“…We found, however, that the minimal VIP concentration efficient to increase Mel release was higher (above 10 .7 M) than that necessary to enhance cAMP 3 x 10-SM (Kaneko et al, 1980) and 10-9M (Kaku et al, 1985) or to activate NAT (10-SM: Yuwiller, 1983 b). This discrepancy could be related either (1) to the fact that Mel release is the last step of the physiological events, (2) to the perifusion technique which may prevent indole accumulation 76 V. Simonneaux et al in the medium or (3) to a possible VIP degradation by specific pineal enzymes as suggested by Kaku et al (1983). In the present study, the intensity of Mel secretion following a 10-6M VIP stimulation was found to be lower in the experiments shown in Fig Previous authors generally compared the effect of VIP on cAMP accumulation or on NAT induction with that of Iso (Yuwiller, 1983 b) or NA (Kaneko et al, 1980;Kaku et al, 1985;Morgan et al, 1988).…”