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Innervation of the pancreas by vasoactive intestinal polypeptide (VIP) immunoreactive nerves
Lifn Sciences, Vol . 22 pp . 773-780 Printed in the II .S .A .
Pergamon
Press
INNERVATION OF THE PANCREAS BY VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) IMMUNOREACTIVE NERVES L .-I . Larsson,
de Muckadell
J . Fahrerkrug, J .J . Holst and O .B . Schaffalitzky
Institute of Medical Biochemistry, University of Aarhus, Aarhus, and the Department of Clinical Chemistry, Bispebjerq Hospital, DR-2400 Copenhagen NV, Denmark . (Received is final form January 13, 1978)
Summa The vasoactive intestinal polypeptide (VIP) has been shown to exert effects on endocrine and exocrine pancreatic secretion . iamzunocytochemistry reveals that VIP immunoreactive nerves occur in the porcine, canine, feline and avian pancreas . In the pancreas of pig and cat VIP nerves are abundant around non-immunoreactive nerve cell bodies of the intrapancreatic ganglia but scarce in the islets and in the exocrine parenchyma . In the dog pancreas, however, the intrapancreatic ganglia contain strongly immunoreactive VIP nerve cell bodies which give off axons that seem to heavily innervate vessels as well as endocrine and exocrine cells . We suggest that in the pig and cat the pancreatic VIP nerves mainly affect the activity of a second type of intrapancreatic neuron, whose transmitter is unknown, whereas in the dog pancreas VIP nerves directly contact their putative effector structures . The vaßoactive intestinal polypeptide (VIP) possesses a spectrum of biological activities (1) . To a large extent these activities reflect the close structural similarity between VIP and the hormones glucagon, secretin and gastric inhibitory polypeptide (1) . it is, however, not yet known which actions that are physiologically important . Recent immunocytochemical and radioimmunochemical studies have indicated the presence of VIP in a system of widely distributed nerves (2-5) . By electron microscopic imsnunocytochemistry VIP has been localized to granules present in the terminals of these unique (p-type or "peptidergic") nerves (6) . Gel chromatographical and radioimmunochemical dilution experiments strongly indicate that the imrnunochemically demonstrated peptide in the brain, gastrointestinal and genitourinary tract is identical to the vasoactive peptide isolnted by Said and Mutt (3,5,7) . The presence of neuronal VIP, possibly having a neurotransmitter function, makes interpretations of its physiological role difficult . Hence, an investigation of the distribution of VIP nerves is of great importance . In the present work the distribution of VIP nerves in the mammalian and avian pancreas was studied since VIP has been shown 0300-9653/78/0306-0727$02 .00/0 Copyright © 1978 Pergamon Press
774
Pancreatic VIP Nerves
Vol . 22, No . 9, 1978
to exert powerful effects on pancreatic exocrine and endocrine secretion (8,9,10) . Methods Pancreatic tissue material from five pigs, ten mongrel dogs, ten cats and two ducks was used . Pig material was collected in local slaughter-houses, (~pgs and cats were killed by an over-dose of mebumal (Nembutal ) and ducks were decapitated . Between 5-15 tissue specimens from each animal were examined . The specimens were rapidly dissected out, frozen in melting Freon-22, freezedried, vapor-fixed with diethylpyrocarbonate and embedded in paraffin in vacuo (3) . Deparaffinized 3~ sections were allowed to react for 24 hours with an 1 :5120 dilution of VIP antiserum No . 5603 . This antiserum fails to react with other gastrointestinal hormonal peptides (3,11), and is dependent upon the major portion of the VIP molecule for binding (5) . The site of antigenantibody reaction was revealed with the peroxidase-antiperoxidase (PAP) procedure of Sternberger (12) . Controls were those suggested by Sternberger (12) and included the application of antigeninactivated antiserum (30 nmol VIP per ml antiserum diluted 1 :80) . Results VIP immunoreactive nerves were detected in the pancreas of all species studied . All controls were negative . The distribution of pancreatic VIP nerves was subject to a pronounced species variation and the results are hence presented separately for each species . In no species were VIP-containing islet cells detected . Scattered VIP nerves were found to occur between adjoining pancreatic acini . The nerves showed a characteristic beaded appearance and occurred in close proximity to the acinar cells . In addition, occasional VIP nerves were seen in association with minute arteries (or arterioles) of the pancreatic parenchyma . The nerves were, however, never numerous in either of these two locations . In contrast, ganglia, which occurred embedded in the pancreatic parenchyma, were found to receive an abundant supply Thus, beaded VIP fibers were found to encircle of VIP nerves . practically every ganglionic cell body . No immunoreactive nerve cell bodies were detected in the pig pancreas, suggesting an Only very rarely were VIP extraneous source of the VIP nerves . nerves seen inside or in the vicinity of islets . Pi~C :
The dog was the species having the most abundant VIP nerve supply . Beaded and occasionally smooth VIP nerve fibers were found to encircle most acini in a pattern suggestive of inner Small and large intrapancreatic arteries were supplied vation . with VIP nerves at the zone of transition between the vascular media and adventitia . Especially at the periphery of the pancreas, connective tissue septa were found to contain bundles of VIP-immunoreactive as well as unreactive nerves (Fig . 1) . A
Vol . 22, No . 9, 1978
Pancreatic VIP Nerves
77 5
Fig . 1 . Section from dog pancreas stained with VIP antiserum. Bundles of strongly immunoreactive VIP nerves are seen . The VIP nerves probably emanate from intrapancreatic ganglia since occasionally transitions between these structures are seen (x 310) .
Fig . 2 . Ganglion of VIP antiserum . Note immunoreactive nerve immunoreactive nerve
dog pancreas stained with the predominance of VIP cell bodies that give off processes (x 340) .
single bundle could contain as much as 20-30 separate VIP nerves . Pancreatic ganglia were frequently found . In contrast to ganglia seen in the pig and cat pancreas, strongly VIP immunoreactive nerve cell bodies were frequently encountered (Fig . 2) . In many ganglia all nerve cells were VIP immunoreactive . The ganglionic cells were found to give off nerve processes that also were strongly VIP positive . Bundles of such processes were detected at the periphery of the ganglia . Pancreatic islets were regularly found to contain a few scattered VIP nerves . Cat : VIP nerves were few but were regularly detected around sôme exocrine acini . Rare singular VIP nerves were sometimes
776
pancreatic DZP Nerves
901. 22, No . 9, 1978
seen in association with islets and arteris but, as in the pig, most VIP nerves occurred in or around pancreatic ganglia . Thus, beaded VIP nerves were seen between and around non-immunoreactive ganglionic cell bodies (Fig . 3) . As in the pig no VIP-containing pancreatic nerve cell somas were observed .
Fig . 3 . Sections from cat pancreas showing two intrapancreatic ganglia that are heavily supplied with varicose VIP nerve terminals . The varicosities appear as dark dots in the photomicrographs . Note complete absence of immunoreactive nerve cell bodies (left x 480, right x 240) . Duck : VIP nerves occurred around some, but by far not all, pancreatic acini . Occasional VIP nerves were seen around intrapancreatic arteries and very rarely VIP nerves occurred in the proximity of pancreatic islets . No ganglia were detected . Discussion The present results show that in all species studied VIP nerves occur around pancreatic acinar cells . The amount of VIP nerves, however, varies considerably . Thus, while VIP nerves are very numerous in the exocrine parenchyma of the dog pancreas they are more scarce, although regularly detected, in the cat, pig and duck . Studies on the human and mucine pancreas (Larsson : unpublished data) indicate that the VIP nerves are even less numerous in these species . Radioimmunoassay studies show that the concentration of VIP immunoreactivity in the pig pancreas is much lower than VIP concentrations measured in intestinal extracts . In accord with this, immunocytochemistry reveals many more nerves in the intestinal tract than in the pancreas of the pig . Similar results have been noted also with the cat and dog pancreas and intestinal tract (cf reference 3 and unpublished observations) . In all species studied the pancreatic VIP nexyes showed a characteristic beaded appearance in the vicinity of the acinar cells . This morphological feature suggests, but does not prove, the presence of a true innervation . Beaded VIP nerves were in addition found in association with arteries and, more rarely, with pancreatic islets . Whereas the presence of strongly immunoreactive ganglionic cell bodies in the dog pancreas suggests that these may provide the source of the pancreatic VIP nerves, such cell bodies were not
Vol . 22~ No . 9, 1978
Pancreatic PIP Nerves
77 7
encountered in the feline or porcine pancreas . Intrapancreatic ganglia of these species were instead found to be supplied with a dense network of beaded VIP nerves which encircled almost every ganglionic cell body in an innervation-like pattern . Three different explanations to this descrepancy may be offered : 1) The VIP nerves of the porcine and feline pancreas derive from cell bodies situated outside the pancreas . Hence, in these two species the VIP-nerves would function chiefly by affecting the activity of non-VIP neurons ; 2) For unknown reasons, VIP nerve cell bodies of pig and cat, but not of dog, may store VIP in amounts too low to be visualized . Thie seems, however, to be an unlikely explanation since pancreatic ganglion cells of the two first mentioned species were densely encircled by varicose VIP nerve terminals whereas this pattern never was encountered in the dog pancreas ; 3) VIP-containing nerve cell bodies occur in the pancreas of both dog, pig and cat . Other non-VIP-containing ganglion cells receive VIP-immunoreactive fibers from ganglia containing VIP nerves cell bodies . Our failure to detect both types of ganglia in any species would then be due to a sampling error . While theoretically possible, the number of samples and animals investigated makes this explanation unlikely . Hence, we are left with the explanation that a true and important species difference exists in the innervation of the pancreas . This difference is schematically illustrated in Fig . 4 .
PIG,CAT Fig . 4 . Schematic drawing illustrating our present working hypothesis on the VIP innervation of the pancreas . In certain species (pig, cat) VIP nerves make rather insignificant contributions to the innervation of the islets, vessels and acini (broken lines), but heavily innervate pancreatic ganglia (full lines) . From these ganglia non-VIP immunoreactive nerves emanate . Such nerves may in turn make contact with the other pancreatic structures . In the dog, ganglionic VIP nerve cell bodies give off numerous VIP nerves that innervate acini, vessels and islets .
non-VIP n~rve~
778
pancreatic VZ~ Nerves
Vol.
22,
No .
9, 1978
Recent immunocytochemical studies by Buffs and co-workers (13) have indicated the presence of VIP-immunoreactive endocrine cells in the islets of dog and guinea pig pancreas . These findings have not been confirmed in other species . Whereas low dilutions of the antiserum used were required to demonstrate endocrine-like cells, only nerves were seen at higher dilutions (E . Solcia : personal communication and personal observation) . The antiserum used in the present study fails to demonstrate pancreatic endocrine cells . In all probability these inconsistencies reflect differing specificities of different VIP antisera . While available radioimmunoanalytical, gel chromatographical and immunocytochemical results (2-7,14) all indicate that VIP is present in nerves, the nature of the VIP immunoreactivity occurring in endocrine cells remains to be established (cf 14) . VIP increases pancreatic bicarbonate secretion (10) and is a powerful stimulant of pancreatic glucagon release (9) . The presence of VIP-containing nerves in the vicinity of acinar and islet cells suggests that a local release of neuronal VIP may be important for stimulating pancreatic endocrine and exocrine secretion . Acknowledgement This study was supported by the Danish Medical Research Council . References
2. 3. 4. 5. 6. 7,
11, 12 . 13 . 14 .
S .I, SAID, In : Gastrointestinal Hormones (edit . by J .C . Thompson), Univers ty o Texas Press, Austin, 1975, p . 591-597 . S .I . SAID and R.N . ROSENBERG, Science 192, 907-908 (1976) . DE L.-I . LARSSON, J . FAHRENRRUG, O.BSCHAFk'ALITZRX . MUCKADELL, F . SUNDLER, R. HAKANSON and J .F . REHFELD, Proc . Natl . Acad . Sci . U .S .A . 73, 3197-3200 (1976) . M.G . BRYANT, S .R . BLOOM, J .M . POLAR, R .H . ALBUQUERQUE, I . MODLIN and A .G .E . PEARSE, Lancet I, 991-993 (1976) . L.-I . LARSSON, J . FAHRENRRUG an~0 B. SCAHAFFALITZKY DE MUCKADELL, Science f97, 1374-1375 (1977) . L .-I . LARSSON,H~ticFi~istry 54, 173-176 (1977? . L .-I . LARSSON, J . FAHRENRRUG and O .B . SCAHFFALITZKX DE MUCKADELL, Life Sciences _21, 503-508 (1977) . M . SCHEBALIN, A .M . BROOKS, S .I . SAID and G .M . MARHLOUF, Gastroenterology _66, 772 (1974) . M . SCHEBALIN, S .I SAID and G .M . MARHLOUF, Am . J . Physiol . 232, E197-E200 (1977) . .M G . MnRUrnUF and S .I . SAID, In : Gastrointestinal Hormones (edit. by J .C . Thompson), Univers ty o Texas Press, us n, 1975, p . 599-610 . J . FASRENRRUG and O .B . SCHAFFALITZRY DE MUCKADELL, J . Lab . clin . Med . 89, 1379-1388 (1977) . L .A . STERNBÉRGER, Imlonunoc tochemist , Prentice-Hall Inc ., Englewood Cliffs, N .J . R . BUFFA, C . CAPELLA, E . SOLCIA, B . FRIGERIO and S .I . SAID, Hietochem~istry 50, 217-227 (1977) . E . SOLCTA, J .M, POLAK, A.G .E . PEARSE, W .G . FORSSMANN, L .-I . LARSSON, F . SUNDLER, J . LECHAGO, L . GRIMELIUS, T. FUJITA, W. CREUTZFELDT, W. GEPTS, S . FALRMER, G . LEFRANC, P . HEITZ,
Vol . 22~ Np . 9, 1978
Pancreatic pIP Nerves
77 9
C . BORDI, E . HAGE, A .M .J . BUCHAN, S .R . BLOOM and M .I . GROSSMAN, In : Gut Hormones (edit . by S .R . Bloom), ChurchillLivingstone, E n urg , 77 (in press) .
Pergamon
Press
INNERVATION OF THE PANCREAS BY VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) IMMUNOREACTIVE NERVES L .-I . Larsson,
de Muckadell
J . Fahrerkrug, J .J . Holst and O .B . Schaffalitzky
Institute of Medical Biochemistry, University of Aarhus, Aarhus, and the Department of Clinical Chemistry, Bispebjerq Hospital, DR-2400 Copenhagen NV, Denmark . (Received is final form January 13, 1978)
Summa The vasoactive intestinal polypeptide (VIP) has been shown to exert effects on endocrine and exocrine pancreatic secretion . iamzunocytochemistry reveals that VIP immunoreactive nerves occur in the porcine, canine, feline and avian pancreas . In the pancreas of pig and cat VIP nerves are abundant around non-immunoreactive nerve cell bodies of the intrapancreatic ganglia but scarce in the islets and in the exocrine parenchyma . In the dog pancreas, however, the intrapancreatic ganglia contain strongly immunoreactive VIP nerve cell bodies which give off axons that seem to heavily innervate vessels as well as endocrine and exocrine cells . We suggest that in the pig and cat the pancreatic VIP nerves mainly affect the activity of a second type of intrapancreatic neuron, whose transmitter is unknown, whereas in the dog pancreas VIP nerves directly contact their putative effector structures . The vaßoactive intestinal polypeptide (VIP) possesses a spectrum of biological activities (1) . To a large extent these activities reflect the close structural similarity between VIP and the hormones glucagon, secretin and gastric inhibitory polypeptide (1) . it is, however, not yet known which actions that are physiologically important . Recent immunocytochemical and radioimmunochemical studies have indicated the presence of VIP in a system of widely distributed nerves (2-5) . By electron microscopic imsnunocytochemistry VIP has been localized to granules present in the terminals of these unique (p-type or "peptidergic") nerves (6) . Gel chromatographical and radioimmunochemical dilution experiments strongly indicate that the imrnunochemically demonstrated peptide in the brain, gastrointestinal and genitourinary tract is identical to the vasoactive peptide isolnted by Said and Mutt (3,5,7) . The presence of neuronal VIP, possibly having a neurotransmitter function, makes interpretations of its physiological role difficult . Hence, an investigation of the distribution of VIP nerves is of great importance . In the present work the distribution of VIP nerves in the mammalian and avian pancreas was studied since VIP has been shown 0300-9653/78/0306-0727$02 .00/0 Copyright © 1978 Pergamon Press
774
Pancreatic VIP Nerves
Vol . 22, No . 9, 1978
to exert powerful effects on pancreatic exocrine and endocrine secretion (8,9,10) . Methods Pancreatic tissue material from five pigs, ten mongrel dogs, ten cats and two ducks was used . Pig material was collected in local slaughter-houses, (~pgs and cats were killed by an over-dose of mebumal (Nembutal ) and ducks were decapitated . Between 5-15 tissue specimens from each animal were examined . The specimens were rapidly dissected out, frozen in melting Freon-22, freezedried, vapor-fixed with diethylpyrocarbonate and embedded in paraffin in vacuo (3) . Deparaffinized 3~ sections were allowed to react for 24 hours with an 1 :5120 dilution of VIP antiserum No . 5603 . This antiserum fails to react with other gastrointestinal hormonal peptides (3,11), and is dependent upon the major portion of the VIP molecule for binding (5) . The site of antigenantibody reaction was revealed with the peroxidase-antiperoxidase (PAP) procedure of Sternberger (12) . Controls were those suggested by Sternberger (12) and included the application of antigeninactivated antiserum (30 nmol VIP per ml antiserum diluted 1 :80) . Results VIP immunoreactive nerves were detected in the pancreas of all species studied . All controls were negative . The distribution of pancreatic VIP nerves was subject to a pronounced species variation and the results are hence presented separately for each species . In no species were VIP-containing islet cells detected . Scattered VIP nerves were found to occur between adjoining pancreatic acini . The nerves showed a characteristic beaded appearance and occurred in close proximity to the acinar cells . In addition, occasional VIP nerves were seen in association with minute arteries (or arterioles) of the pancreatic parenchyma . The nerves were, however, never numerous in either of these two locations . In contrast, ganglia, which occurred embedded in the pancreatic parenchyma, were found to receive an abundant supply Thus, beaded VIP fibers were found to encircle of VIP nerves . practically every ganglionic cell body . No immunoreactive nerve cell bodies were detected in the pig pancreas, suggesting an Only very rarely were VIP extraneous source of the VIP nerves . nerves seen inside or in the vicinity of islets . Pi~C :
The dog was the species having the most abundant VIP nerve supply . Beaded and occasionally smooth VIP nerve fibers were found to encircle most acini in a pattern suggestive of inner Small and large intrapancreatic arteries were supplied vation . with VIP nerves at the zone of transition between the vascular media and adventitia . Especially at the periphery of the pancreas, connective tissue septa were found to contain bundles of VIP-immunoreactive as well as unreactive nerves (Fig . 1) . A
Vol . 22, No . 9, 1978
Pancreatic VIP Nerves
77 5
Fig . 1 . Section from dog pancreas stained with VIP antiserum. Bundles of strongly immunoreactive VIP nerves are seen . The VIP nerves probably emanate from intrapancreatic ganglia since occasionally transitions between these structures are seen (x 310) .
Fig . 2 . Ganglion of VIP antiserum . Note immunoreactive nerve immunoreactive nerve
dog pancreas stained with the predominance of VIP cell bodies that give off processes (x 340) .
single bundle could contain as much as 20-30 separate VIP nerves . Pancreatic ganglia were frequently found . In contrast to ganglia seen in the pig and cat pancreas, strongly VIP immunoreactive nerve cell bodies were frequently encountered (Fig . 2) . In many ganglia all nerve cells were VIP immunoreactive . The ganglionic cells were found to give off nerve processes that also were strongly VIP positive . Bundles of such processes were detected at the periphery of the ganglia . Pancreatic islets were regularly found to contain a few scattered VIP nerves . Cat : VIP nerves were few but were regularly detected around sôme exocrine acini . Rare singular VIP nerves were sometimes
776
pancreatic DZP Nerves
901. 22, No . 9, 1978
seen in association with islets and arteris but, as in the pig, most VIP nerves occurred in or around pancreatic ganglia . Thus, beaded VIP nerves were seen between and around non-immunoreactive ganglionic cell bodies (Fig . 3) . As in the pig no VIP-containing pancreatic nerve cell somas were observed .
Fig . 3 . Sections from cat pancreas showing two intrapancreatic ganglia that are heavily supplied with varicose VIP nerve terminals . The varicosities appear as dark dots in the photomicrographs . Note complete absence of immunoreactive nerve cell bodies (left x 480, right x 240) . Duck : VIP nerves occurred around some, but by far not all, pancreatic acini . Occasional VIP nerves were seen around intrapancreatic arteries and very rarely VIP nerves occurred in the proximity of pancreatic islets . No ganglia were detected . Discussion The present results show that in all species studied VIP nerves occur around pancreatic acinar cells . The amount of VIP nerves, however, varies considerably . Thus, while VIP nerves are very numerous in the exocrine parenchyma of the dog pancreas they are more scarce, although regularly detected, in the cat, pig and duck . Studies on the human and mucine pancreas (Larsson : unpublished data) indicate that the VIP nerves are even less numerous in these species . Radioimmunoassay studies show that the concentration of VIP immunoreactivity in the pig pancreas is much lower than VIP concentrations measured in intestinal extracts . In accord with this, immunocytochemistry reveals many more nerves in the intestinal tract than in the pancreas of the pig . Similar results have been noted also with the cat and dog pancreas and intestinal tract (cf reference 3 and unpublished observations) . In all species studied the pancreatic VIP nexyes showed a characteristic beaded appearance in the vicinity of the acinar cells . This morphological feature suggests, but does not prove, the presence of a true innervation . Beaded VIP nerves were in addition found in association with arteries and, more rarely, with pancreatic islets . Whereas the presence of strongly immunoreactive ganglionic cell bodies in the dog pancreas suggests that these may provide the source of the pancreatic VIP nerves, such cell bodies were not
Vol . 22~ No . 9, 1978
Pancreatic PIP Nerves
77 7
encountered in the feline or porcine pancreas . Intrapancreatic ganglia of these species were instead found to be supplied with a dense network of beaded VIP nerves which encircled almost every ganglionic cell body in an innervation-like pattern . Three different explanations to this descrepancy may be offered : 1) The VIP nerves of the porcine and feline pancreas derive from cell bodies situated outside the pancreas . Hence, in these two species the VIP-nerves would function chiefly by affecting the activity of non-VIP neurons ; 2) For unknown reasons, VIP nerve cell bodies of pig and cat, but not of dog, may store VIP in amounts too low to be visualized . Thie seems, however, to be an unlikely explanation since pancreatic ganglion cells of the two first mentioned species were densely encircled by varicose VIP nerve terminals whereas this pattern never was encountered in the dog pancreas ; 3) VIP-containing nerve cell bodies occur in the pancreas of both dog, pig and cat . Other non-VIP-containing ganglion cells receive VIP-immunoreactive fibers from ganglia containing VIP nerves cell bodies . Our failure to detect both types of ganglia in any species would then be due to a sampling error . While theoretically possible, the number of samples and animals investigated makes this explanation unlikely . Hence, we are left with the explanation that a true and important species difference exists in the innervation of the pancreas . This difference is schematically illustrated in Fig . 4 .
PIG,CAT Fig . 4 . Schematic drawing illustrating our present working hypothesis on the VIP innervation of the pancreas . In certain species (pig, cat) VIP nerves make rather insignificant contributions to the innervation of the islets, vessels and acini (broken lines), but heavily innervate pancreatic ganglia (full lines) . From these ganglia non-VIP immunoreactive nerves emanate . Such nerves may in turn make contact with the other pancreatic structures . In the dog, ganglionic VIP nerve cell bodies give off numerous VIP nerves that innervate acini, vessels and islets .
non-VIP n~rve~
778
pancreatic VZ~ Nerves
Vol.
22,
No .
9, 1978
Recent immunocytochemical studies by Buffs and co-workers (13) have indicated the presence of VIP-immunoreactive endocrine cells in the islets of dog and guinea pig pancreas . These findings have not been confirmed in other species . Whereas low dilutions of the antiserum used were required to demonstrate endocrine-like cells, only nerves were seen at higher dilutions (E . Solcia : personal communication and personal observation) . The antiserum used in the present study fails to demonstrate pancreatic endocrine cells . In all probability these inconsistencies reflect differing specificities of different VIP antisera . While available radioimmunoanalytical, gel chromatographical and immunocytochemical results (2-7,14) all indicate that VIP is present in nerves, the nature of the VIP immunoreactivity occurring in endocrine cells remains to be established (cf 14) . VIP increases pancreatic bicarbonate secretion (10) and is a powerful stimulant of pancreatic glucagon release (9) . The presence of VIP-containing nerves in the vicinity of acinar and islet cells suggests that a local release of neuronal VIP may be important for stimulating pancreatic endocrine and exocrine secretion . Acknowledgement This study was supported by the Danish Medical Research Council . References
2. 3. 4. 5. 6. 7,
11, 12 . 13 . 14 .
S .I, SAID, In : Gastrointestinal Hormones (edit . by J .C . Thompson), Univers ty o Texas Press, Austin, 1975, p . 591-597 . S .I . SAID and R.N . ROSENBERG, Science 192, 907-908 (1976) . DE L.-I . LARSSON, J . FAHRENRRUG, O.BSCHAFk'ALITZRX . MUCKADELL, F . SUNDLER, R. HAKANSON and J .F . REHFELD, Proc . Natl . Acad . Sci . U .S .A . 73, 3197-3200 (1976) . M.G . BRYANT, S .R . BLOOM, J .M . POLAR, R .H . ALBUQUERQUE, I . MODLIN and A .G .E . PEARSE, Lancet I, 991-993 (1976) . L.-I . LARSSON, J . FAHRENRRUG an~0 B. SCAHAFFALITZKY DE MUCKADELL, Science f97, 1374-1375 (1977) . L .-I . LARSSON,H~ticFi~istry 54, 173-176 (1977? . L .-I . LARSSON, J . FAHRENRRUG and O .B . SCAHFFALITZKX DE MUCKADELL, Life Sciences _21, 503-508 (1977) . M . SCHEBALIN, A .M . BROOKS, S .I . SAID and G .M . MARHLOUF, Gastroenterology _66, 772 (1974) . M . SCHEBALIN, S .I SAID and G .M . MARHLOUF, Am . J . Physiol . 232, E197-E200 (1977) . .M G . MnRUrnUF and S .I . SAID, In : Gastrointestinal Hormones (edit. by J .C . Thompson), Univers ty o Texas Press, us n, 1975, p . 599-610 . J . FASRENRRUG and O .B . SCHAFFALITZRY DE MUCKADELL, J . Lab . clin . Med . 89, 1379-1388 (1977) . L .A . STERNBÉRGER, Imlonunoc tochemist , Prentice-Hall Inc ., Englewood Cliffs, N .J . R . BUFFA, C . CAPELLA, E . SOLCIA, B . FRIGERIO and S .I . SAID, Hietochem~istry 50, 217-227 (1977) . E . SOLCTA, J .M, POLAK, A.G .E . PEARSE, W .G . FORSSMANN, L .-I . LARSSON, F . SUNDLER, J . LECHAGO, L . GRIMELIUS, T. FUJITA, W. CREUTZFELDT, W. GEPTS, S . FALRMER, G . LEFRANC, P . HEITZ,
Vol . 22~ Np . 9, 1978
Pancreatic pIP Nerves
77 9
C . BORDI, E . HAGE, A .M .J . BUCHAN, S .R . BLOOM and M .I . GROSSMAN, In : Gut Hormones (edit . by S .R . Bloom), ChurchillLivingstone, E n urg , 77 (in press) .