Strategy in the choice of synthetic peptides for the immunization — radioimmunoassay and immunocytochemistry

$6 INTERCELLULAR COMMUNICATIONMEDIATED BY VlP IN THE CEREBRAL CORTEX. Pierre J. M a g i s t r e t t i , D~partement de Pharmacologie - Centre M~dica] U n i v e r s i t a i r e 1211 Geneva, Switzerland. A growing number of b i o l o g i c a l l y active peptides is being i d e n t i f i e d w i t h i n the CNS. According to c u r r e n t l y accepted c r i t e r i a several of these peptides, including VIP, can be viewed as neurotransmitters. However, t h e i r precise function in central neurotransmission and t h e i r role as elements of the neurotransmitter code are s t i l l elusive. Recent pharmacological and immunohistochemical studies have addressed t h i s question f o r VIP and suggest a possible function of VIP-containing neurons in rodent cerebral cortex. Here VIP may act, at ~ s t in part, as a local neurohormone to maintain a homeostatic e q u i l i b r i u m w i t h i n discrete c o r t i c a l domains in response to changes in local neuronal a c t i v i t y . The experimental evidences can be summarized as follows : ( I ) VIP neurons c o n s t i t u t e a rather homogeneous population of i n t r a c o r t i c a l , r a d i a l l y oriented bipolar c e l l s whose arborization pattern defines p a r t i a l l y overlapping c o r t i c a l columns. On the average there is one VIP-containing neuron per column of 30 um diameter. (2) VIP promotes glycogen hydrolysis in v i t r o with an EC50 of 25 riM. This e f f e c t is rapid, r e v e r s i b l e and pharmacological s]y--~-fiec-ffic. y (3) VlP has d i r e c t vasodilatory effects on cerebral a r t e r i e s and stimulates cAMP formation in cerebral c o r t i c a l microvessels in v i t r o . (4) VIP promotes glycogeno]ysis in cultured astrocytes. This set of observations suggests a functional role for VIP c o r t i c a l neurons in the coupling between energy metabolism, 51ood flow and neuronal a c t i v i t y at the f i n e s t level of c o r t i c a l r e s o l u t i o n . Furthermore, VIP interacts with noradrenaline (NA), another c o r t i c a l neurotransmitter which displays metabolic actions. Thus VIP and NA act s y n e r g i s t i c a l l y to increase cAMP levels in mouse cerebral c o r t i c a l s l i c e s . The f u n c t i o n a l consequence of such a synergism is that the concomitant release of VIP and NA w i t h i n a discrete volume of cerebral cortex can generate a " c o r t i c a l metabolic hot spot" where cAMP levels are increased d r o s t i c a ! ] y and with great spatial s e l e c t i v i t y .

STRATEGY IN THE CHOICE OF SYNTHETIC PEPTIDES FOR THE IMMUNIZATION - RADIOIMMUNOASSAY AND IMMUNOCYTOCHEMISTRY Noboru Yanaihara Laboratory of Bioorganic Chemistry, Shizuoka College of Pharmacy, Shlzuoka and Laboratory of Cellular Metabolism, National Institute for Physiological Science, Okazakl, Japan. Measurement and locallzation of biologically active peptldes depends upon the production of specific antlsera. Synthetic peptides possessing either the full amino acid sequence of naturally occurring peptides or those of fragments, analogs or segments of precursors can be employed as antigens. The use of properly constructed synthetic peptides enhances the likelihood of generating an antiseram having the desired specificity. For RIA, the specificity of the assay system is dependent upon tracer integrity, standard quality as well as the antibody recognition characteristics. Use of these principles has proved successful in the development of proinsulin C-peptide, glicentin, PHI and IGF-I C-domaln antlsera.