228 NEUROPEPTIDES

nent of the baroreceptor reflex. A larger increase in BP was (D-Ala’)-Deltorphin-I (DADTI) belongs to a new family observed a&r i.v. administration of the peptide (100-200 of opioid eptapeptides, extracted from the skin of the @Kg). However, this treatment also produced tachycar- South American frog Phyllomedusa bicolor.’ It displays dia without altering baroreceptor reflex responses. These high affinity and selectivity for delta opiod receptors. The results suggest that FSFa receptors in the NTS are involved D-amino acid in position two and the sequence of the in the control of BP in the rat. However F8Fa receptors in COOH-terminal tetrapeptide are essential for its pharma- the NTS are probably not responsible for the CV effects cological activity: when injected i.c.v. in rats, it stimulates observed after i.v. administration of the octapeptide. locomotion, sniffing and oral stereotipies.

P98 Amygdaloid Neuropeptide Receptors: Regulation of Cyclic AMP Efflux T. D. Ely, S. E. Eldon, C. D. Kilts Emory University, Atlanta, Georgia 30322, USA

The amygdaloid complex contains a remarkable density and diversity of neuropeptide-containing cells and recep- tors, The adenylate cyclase second messenger system has been implicated in neuropeptide receptor signal trans- duction in neuronal and non-neuronal tissue. We exam- ined the effects of vasoactive intestinal peptide (VIP), corticotropin releasing factor (CRF), 6 and uopiate recep- tor agonists, neurotensin, and somatostatin on basal and stimulated cyclic AMP effhtx from superfused prepara- tions of the rat amygdaloid complex. VIP produced a con- centration-dependent increase in basal amygdaloid cyclic AMP effluxthat was similar in discrete amygdaloid nuclei. CRF failed to affect cyclic AMP efflwr but in the presence of exdogenous GTP, enhanced cyclic AMP synthesis in cell-free homogenates. Both 6 and p opiate receptor ago- nists significantly inhibited the forskolin-induced increase in amygdaloid cyclic AMP efflw; the inhibitory effect of the selctive 6 opiate receptor agonist was blocked by pre- treatment of amygdaloid tissue with pertussis toxin. Neither somatostatin-14 nor -28 affected forskolin- or iso- proterenol-stimulated cyclic AMP efIIux from the amyg- daloid complex. Neurotensin did not affect basal or forskolin or PGE -stimulated cyclic AMP efflux from amygdaloid slices. These results indicate that some amyg- daloid neuropeptide receptors are coupled to the bidirec- tional regulation of cyclic AMP eftlux via the intermediary actions of G proteins, The dependency of receptor-adeny- late cyclase coupling on the study of intact cell versus cell- free neural preparations was illustrated for CRF.

P99 Immunohistochemical Localization and Receptor Binding Autoradiography of (D-AlaZ)-Deltorphin-I in rodent brain T. Renda*, H. Abet, I. Tooyamat, C. Casu*, L. Negri$, P. MelchiorrQ, V. Erspamers and H. Kimura? *Institute of Human Anatomy, University ‘La Sapienza’, Rome, Italy, tInstitute of Molecular Neurobiology, Shiga University of Medical Sciences, Gtsu, Japan, SInsmute of Medical Pharmacology and §Emeritus of Pharmacology, University ‘La Sapienza’, Rome, Italy

Rat brain specimens were studied autoradiographically, using tH)-DADTI. Rat and mouse brain, nasal cavity and eye specimens were immunohistochemically investi- gated, using a newly raised polyclonal antiserum? Autoradiography fully confirmed the selective binding on delta opioid receptors.

Immunoreactive neurons were found in substantia nigra and ventral tegmental ponto-mesencephalic areas. Immunoreactive nerve fibers were mainly shown in acces- sory olfactory bulb, neostriatum, n.accumbens, olfactory tubercle and mesencephalic tegmentum. Moreover, immunoreactive sensory cells were also demonstrated in olfactory mucosa of nasal cavities and vomeronasal organ and in ganglionic layer of fetal retina.

1. Erspamer, V. et al (1989). Proc. Natl. Acad. Sci. USA 86: 5188-5192.

2. Abe, H. et al (1992). NeuroReport 3: 669-672.

Supported by the National Research Council (CNR) of Italy (bilateral project RendaKimura).

PlOO Characterisation of the Tachykinin- induced Hindlimb Thumping Response in Gerbils E. A. Graham, M. P. Turpin and C. M. Stubbs Department of Neuropharmacology, Glaxo Group Research Ltd., Ware, Her&., SG12 ODP, UK

In gerbils, central administration of NKI receptor agonists to gerbils evokes a very distinctive hindlimb thumping response. The aim of these studies was to further charac- terise this response using selective tachykinin receptor agonists and antagonists.

Female Mongolian gerbils (35-45 g) were used. Hindlimb thumping was recorded for 3 min following intracerebroventricular (i.c.v.) injection of NK receptor agonists. ED$O values (dose producing response in 50% of animals) were calculated in the presence and absence of selective tachykinin receptor agonists and antagonists.

The selective NKI receptor agonist, GR73632, pro- duced a dose related increase in the incidence of thump- ing (ED50 = 5.3 (1.0-l 9.l)pmol, n = 6). The selective NKz receptor agonist, GR64349, and the selective NIG recep- tor agonist, se&tide, were only active at high doses (EDso values of > 2050 and 95 (54-l 84) pmol respectively). The selective NK receptor antagonists, GR82334 (1 .O nmol, i.c.v. co-administration), and racemic CP-96,345 (30 molkg, s.c., 15 min pretreatment) both caused rightward shifts in the dose-response curve for GR73632 (dose ratios