We examined the effects of orexin A on the mRNA levels of neuropeptide Y, agouti-related peptide, melanin-concentrating hormone, prepro-orexin and orexin receptors in the rat hypothalamus. Adult male rats were treated centrally (i.c.v.) with a single dose of orexin A (3 nmol). After 2, 6 and 12 h, neuropeptide Y, agouti-related peptide, melanin-concentrating hormone, and prepro-orexin mRNA levels were measured by semiquantitative RT-PCR and in situ hybridization; orexin receptors mRNA content was quantified by semiquantitative RT-PCR. We found that orexin A increased neuropeptide Y expression in the arcuate nucleus of the rat hypothalamus. This stimulatory effect was transient, being observed 2 h after the treatment, and disappearing after longer periods (6 and 12 h). In contrast, no change was demonstrated in hypothalamic agouti-related peptide, melanin-concentrating hormone, prepro-orexin or orexin receptors mRNA levels at any time evaluated. Our results suggest that neuropeptide Y synthesized in the arcuate nucleus of the hypothalamus, but not agouti-related peptide and melanin-concentrating hormone pathways, is likely involved in orexin-induced feeding behavior, and raise the possibility that this functional linkage may also be involved in other actions mediated by orexins such as locomotor activity and sympathetic function.

Keywords:
Orexins, Neuropeptide Y, Agouti-related peptide, Melanin-concentrating hormone, Orexin receptors, Feeding behavior
1.
Kalra SP, Dube MG, Pu S, Xu B, Horvath TL, Kalra PS: Interacting appetite-regulating pathways in the hypothalamic regulation of body weight. Endocr Rev 1999;20:68–100.
2.
Meister B: Control of food intake via leptin receptors in the hypothalamus. Vitam Horm 2000;59:265–304.
3.
Bray LS, Smith MA, Gold PW, Herkenham M: Altered expression of hypothalamic neuropeptide mRNAs in food-restricted and food-deprived rats. Neuroendocrinology 1990;52:441–447.
4.
Qu D, Ludwig DS, Gammeltoft S, Piper M, Pelleymounter MA, Cullen MJ, Mathes WF, Przypek R, Kanarek R, Maratos-Flier E: A role for melanin-concentrating hormone in the central regulation of feeding behaviour. Nature 1996;380:243–247.
5.
Sakurai T, Amemiya A, Ishii M, Matsuzaki I, Chemelli R, Tanaka H, Willians S, Richardson J, Kozlowski G, Wilson S, Arch J, Buckingham R, Haynes A, Carr S, Annan R, MacNutty D, Li W, Terrett J, Elshourbagy N, Bergsma D, Yanagisawa M: Orexins and orexins receptors: A family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behaviour. Cell 1998;92:573–585.
6.
Ziotopoulou M, Erani DM, Hileman SM, Bjorbaek C, Mantzoros CS: Unlike leptin, ciliary neurotrophic factor does not reverse the starvation-induced changes of serum corticosterone and hypothalamic neuropeptide levels but induces expression of hypothalamic inhibitors of leptin signaling. Diabetes 2000;49:1890–1896.
7.
Rossi M, Kim MS, Morgan DG, Small CJ, Edwards CM, Sunter D, Abusnana S, Goldstone AP, Russell SH, Stanley SA, Smith DM, Yagaloff K, Ghatei MA, Bloom SR: A C-terminal fragment of Agouti-related protein increases feeding and antagonizes the effect of alpha-melanocyte stimulating hormone in vivo. Endocrinology 1998;139:4428–4431.
8.
Edwards CM, Abusnana S, Sunter D, Murphy KG, Ghatei MA, Bloom SR: The effect of the orexins on food intake: Comparison with neuropeptide Y, melanin-concentrating hormone and galanin. J Endocrinol 1999;160:R7–R12.
9.
de Lecea L, Kilduff T, Peyron C, Gao X, Foye P, Danielson P, Fukuhara C, Battenberg E, Gautvik V, Bartlett F, Frankel W, van den Pol A, Bloom F, Gautvik K, Sutcliffe J: The hypocretins: Hypothalamus-specific peptides with neuroexcitatory activity. Proc Natl Acad Sci USA 1998;95:322–327.
10.
Lin L, Faraco J, Li R, Kadotani H, Rogers W, Lin X, Qiu X, de Jong PJ, Nishino S, Mignot E: The sleep disorder canine narcolepsy is caused by a mutation in the hypocretin (orexin) receptor 2 gene. Cell 1999;98:365–376.
11.
Chemelli R, Willie J, Sinton C, Elmquist J, Scammell T, Lee C, Richardson J, Williams S, Xiong Y, Kisanuki Y, Fitch T, Nakazato M, Hammer R, Saper C, Yanagisawa M: Narcolepsy in orexin knockout mice: Molecular genetics of sleep regulation. Cell 1999;98:437–451.
12.
Nishino S, Ripley B, Overeem S, Lammers GJ, Mignot E: Hypocretin (orexin) deficiency in human narcolepsy. Lancet 2000;355:39–40.
13.
Peyron C, Faraco J, Rogers W, Ripley B, Overeem S, Charnay Y, Nevsimalova S, Aldrich M, Reynolds D, Albin R, Li R, Hungs M, Pedrazzoli M, Padigaru M, Kucherlapati M, Fan J, Maki R, Lammers GJ, Bouras C, Kucherlapati R, Nishino S, Mignot E: A mutation in a case of early onset narcolepsy and a generalized absence of hypocretin peptides in human narcoleptic brains. Nat Med 2000;6:991–997.
14.
Hagan JJ, Leslie RA, Patel S, Evans ML, Wattam TA, Holmes S, Benham CD, Taylor SG, Routledge C, Hemmati P, Munton RP, Ashmeade TE, Shah AS, Hatcher JP, Hatcher PD, Jones DN, Smith MI, Piper DC, Hunter AJ, Porter RA, Upton N: Orexin A activates locus coeruleus cell firing and increases arousal in the rat. Proc Natl Acad Sci USA 1999;96:10911–10916.
15.
Ida T, Nakahara K, Katayama T, Murakami N, Nakazato M: Effect of lateral cerebroventricular injection of the appetite-stimulating neuropeptide, orexin and neuropeptide Y, on the various behavioral activities of rats. Brain Res 1999;821:526–529.
16.
Ida T, Nakahara K, Murakami T, Hanada R, Nakazato M, Murakami N: Possible involvement of orexin in the stress reaction in rats. Biochem Biophys Res Commun 2000;270:318–323.
17.
Jones DN, Gartlon J, Parker F, Taylor SG, Routledge C, Hemmati P, Munton RP, Ashmeade TE, Hatcher JP, Johns A, Porter RA, Hagan JJ, Hunter AJ, Upton N: Effects of centrally administered orexin-B and orexin-A: A role for orexin-1 receptors in orexin-B-induced hyperactivity. Psychopharmacology 2001;153:210–218.
18.
Samson WK, Gosnell B, Chang JK, Resch ZT, Murphy TC: Cardiovascular regulatory actions of the hypocretins in brain. Brain Res 1999;831:248–253.
19.
Shirasaka T, Nakazato M, Matsukura S, Takasaki M, Kannan H: Sympathetic and cardiovascular actions of orexins in conscious rats. Am J Physiol 1999;277:R1780–R1785.
20.
Bingham S, Davey PT, Babbs AJ, Irving EA, Sammons MJ, Wyles M, Jeffrey P, Cutler L, Riba I, Johns A, Porter RA, Upton N, Hunter AJ, Parsons AA: Orexin-A, an hypothalamic peptide with analgesic properties. Pain 2001;92:81–90.
21.
van den Pol AN: Hypothalamic hypocretin (orexin): Robust innervation of the spinal cord. J Neurosci 1999;19:3171–3182.
22.
Date Y, Ueta Y, Yamashita H, Yamaguchi H, Matsukura S, Kangawa K, Sakurai T, Yanagisawa M, Nakazato M: Orexins, orexigenic hypothalamic peptides, interact with autonomic, neuroendocrine and neuroregulatory systems. Proc Natl Acad Sci USA 1999;96:748–753.
23.
Pu S, Jain MR, Kalra PS, Kalra SP: Orexins, a novel family of hypothalamic neuropeptides, modulate pituitary luteinizing hormone secretion in an ovarian steroid-dependent manner. Regul Pept 1998;78:133–136.
24.
López M, Seoane L, García MC, Lago F, Casanueva FF, Senarís R, Diéguez C: Leptin regulation of prepro-orexin and orexin receptor mRNA levels in the hypothalamus. Biochem Biophys Res Commun 2000;269:41–45.
25.
Moriguchi T, Sakurai T, Nambu T, Yanagisawa M, Goto K: Neurons containing orexin in the lateral hypothalamic area of the adult rat brain are activated by insulin-induced acute hypoglycemia. Neurosci Lett 1999;264:101–104.
26.
Griffond B, Risold PY, Jacquemard C, Colard C, Fellmann D: Insulin-induced hypoglycemia increases preprohypocretin (orexin) mRNA in the rat lateral hypothalamic area. Neurosci Lett 1999;262:77–80.
27.
Cai XJ, Widdowson PS, Harrold J, Wilson S, Buckingham RE, Arch JR, Tadayyon M, Clapham JC, Wilding J, Williams G: Hypothalamic orexin expression: Modulation by blood glucose and feeding. Diabetes 1999;48:2132–2137.
28.
López M, Seoane L, Señarís R, Diéguez C: Prepro-orexin mRNA levels in the rat hypothalamus, and orexin mRNA levels in the rat hypothalamus and adrenal gland are not influence by thyroid status. Neurosci Lett 2001;300:171–175.
29.
Trivedi P, Yu H, MacNeil D, Van der Ploeg L, Guan X: Distribution of orexin receptor mRNA in the rat brain. FEBS Lett 1999;438:71–75.
30.
Hervieu GJ, Cluderay JE, Harrison DC, Roberts JC, Leslie RA: Gene expression and protein distribution of the orexin-1 receptor in the rat brain and spinal cord. Neuroscience 2001;103:777–797.
31.
López M, Señarís R, Gallego R, García-Caballero T, Lago F, Seoane L, Casanueva F, Diéguez C: Orexin receptors are expressed in the adrenal medulla of the rat. Endocrinology 1999;140:5991–5994.
32.
Kirchgessner AL, Liu M: Orexin synthesis and response in the gut. Neuron 1999;24:941–951.
33.
Elias C, Saper C, Marathos-Flier E, Tritos N, Lee C, Kelly J, Tatro J, Hoffman G, Ollmann M, Barsh G, Sakurai T, Yanagisawa M, Elmquist J: Chemically defined projections linking the mediobasal hypothalamus and the lateral hypothalamic area. J Comp Neurol 1998;402:442–459.
34.
Broberger C, de Lecea L, Sutcliffe J, Hökfelt T: Hypocretin/orexin and melanin concentrating hormone-expressing cells form distinct populations in the rodent lateral hypothalamus: Relationship to the neuropeptide Y and agouti gene related protein systems. J Comp Neurol 1998;402:460–474.
35.
Peyron C, Tighe D, van den Pol A, de Lecea L, Heller H, Sutcliffe J, Kilduff T: Neurons containing hypocretin (orexin) project to multiple neuronal systems. J Neurosci 1998;18:9996–10015.
36.
Horvath T, Diano S, van den Pol A: Synaptic interaction between hypocretin (orexin) and neuropeptide Y cells in the rodent and primate hypothalamus: A novel circuit implicated in metabolic and endocrine regulations. J Neurosci 1999;19:1072–1087.
37.
Yamanaka A, Kunii K, Nambu T, Tsujino N, Sakai A, Matsuzaki I, Miwa Y, Goto K, Sakurai T: Orexin-induced food intake involves neuropeptide Y pathway. Brain Res 1999;859:404–409.
38.
Jain MR, Horvath TL, Kalra PS, Kalra SP: Evidence that NPY Y1 receptors are involved in stimulation of feeding by orexins (hypocretins) in sated rats. Regul Pept 2000;87:19–24.
39.
Ida T, Nakahara K, Kuroiwa T, Fukui K, Nakazato M, Murakami T, Murakami N: Both corticotropin releasing factor and neuropeptide Y are involved in the effect of orexin (hypocretin) on the food intake in rats. Neurosci Lett 2000;293:119–122.
40.
Dube MG, Horvath TL, Kalra PS, Kalra SP: Evidence of NPY Y5 receptor involvement in food intake elicited by orexin A in sated rats. Peptides 2000;21:1557–1560.
41.
Bannon AW, Seda J, Carmouche M, Francis JM, Norman MH, Karbon B, McCaleb ML: Behavioral characterization of neuropeptide Y knockout mice. Brain Res 2000;868:79–87.
42.
Egawa M, Yoshimatsu H, Bray GA: Neuropeptide Y suppresses sympathetic activity to interscapular brown adipose tissue in rats. Am J Phys 1991;260:R1314–R1320.
43.
Lu XY, Bagnol D, Burke S, Akil H, Watson SJ: Differential distribution and regulation of OX1 and OX2 orexin/hypocretin receptor messenger RNA in the brain upon fasting. Horm Behav 2000;37:335–344.
44.
Carro E, Señarís R, Seoane L, Frohman L, Arimura A, Casanueva F, Diéguez C: Role of growth hormone (GH)-releasing hormone and somatostatin on leptin-induced GH Secretion. Neuroendocrinology 1999;69:3–10.
45.
Señarís RM, Lago F, Coya R, Pineda J, Diéguez C: Regulation of hypothalamic somatostatin, growth hormone-releasing hormone, and growth hormone receptor messenger ribonucleic acid by glucocorticoids. Endocrinology 1996;137:5236–5241.
46.
Paxinos G, Watson C: The Rat Brain in Stereotaxic Coordinates. Sydney, Academic Press, 1986.
47.
Akabayashi A, Levin N, Paez X, Alexander JT, Leibowitz F: Hypothalamic neuropeptide Y and its gene expression: Relation to light/dark cycle and circulating corticosterone. Mol Cell Neurosci 1994;5:210–218.
48.
Bluet-Pajot MT, Presse F, Voko Z, Hoeger C, Mounier F, Epelbaum J, Nahon JL: Neuropeptide-E-I antagonizes the action of melanin-concentrating hormone on stress-induced release of adrenocorticotropin in the rat. J Neuroendocrinol 1995;7:297–303.
49.
Taheri S, Sunter D, Dakin C, Moyes S, Seal L, Gardiner J, Rossi M, Ghatei M, Bloom S: Diurnal variation in orexin A immunoreactivity and prepro-orexin mRNA in the rat central nervous system. Neurosci Lett 2000;279:109–112.
50.
Yamada H, Okumura T, Motomura W, Kobayashi Y, Kohgo Y: Inhibition of food intake by central injection of anti-orexin antibody in fasted rats. Biochem Biophys Res Commun 2000;267:527–531.
51.
Li C, Chen P, Smith MS: The acute suckling stimulus induces expression of neuropeptide Y (NPY) in cells in the dorsomedial hypothalamus and increases NPY expression in the arcuate nucleus. Endocrinology 1998;139:1645–1652.
52.
Pu S, Dhillon H, Moldawer LL, Kalra PS, Kalra SP: Neuropeptide Y counteracts the anorectic and weight reducing effects of ciliary neurotropic factor. J Neuroendocrinol 2000;12:827–832.
53.
Hahn TM, Breininger JF, Baskin DG, Schwartz MW: Coexpression of AgRP and NPY in fasting-activated hypothalamic neurons. Nat Neurosci 1998;1:271–272.
54.
Ollmann MM, Wilson BD, Yang YK, Kerns JA, Chen Y, Gantz I, Barsh G: Antagonism of central melanocortin receptors in vitro and in vivo by agouti-related protein. Science 1997;278:135–138.
55.
Hagan MM, Rushing PA, Pritchard LM, Schwartz MW, Strack AM, Van Der Ploeg LH, Woods SC, Seeley RJ: Long-term orexigenic effects of AgRP-(83–132) involve mechanisms other than melanocortin receptor blockade. Am J Physiol 2000;279:R47–R52.
56.
Shimada M, Tritos NA, Lowell BB, Flier JS, Maratos-Flier E: Mice lacking melanin-concentrating hormone are hypophagic and lean. Nature 1998;396:670–674.
© 2002 S. Karger AG, Basel
2002
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.