Expression of purinergic receptors in the hypothalamus of the rat is modified by reduced food availability.
ATP-sensitive P2 receptors are suggested to play an important role in the cerebral signal transduction. We examined the expression of the P2Y1 receptor and the possibly downstream-related neuronal nitric oxide synthase (nNOS) in the hypothalamus of rats food-restricted for 3 or 10 days and rats refed after a restriction of 10 days. The restriction caused a reduction of the body weight and plasma triacylglyceride, an increase of non-esterified fatty acid levels correlating with a decrease of leptin levels and an enhancement of plasma corticosterone. All changes returned to basal levels after refeeding. The restriction induced an enhanced intake within 30 min after food presentation and a reduction in the latency. Interestingly, the latter was not abolished by refeeding. The daily food intake induced by refeeding was enhanced at the first day only. The expression of hypothalamic P2Y1 receptor/nNOS mRNA and protein and of leptin receptor mRNA were enhanced after restricted feeding. These changes were abolished after 3 days of refeeding. Immunofluorescence studies indicated that P2Y1 receptor and nNOS immunoreactivities are present in the dorsomedial, ventromedial and lateral hypothalamus and in the nucleus arcuatus. P2Y1 receptor-positive cells were partially also nNOS-positive. The P2Y1 receptor labeling was restricted to cell bodies of obviously non-glial cells, whereas nNOS labeling could be detected also at cellular processes of these cells. In the nucleus arcuatus, astrocytes were identified, expressing P2Y1 receptors at cell bodies and cellular processes. The data suggest that restricted feeding may enhance the sensitivity of the hypothalamus to extracellular ADP/ATP by regulation of the expression of P2Y1 receptors and possibly of their signal transduction pathway via nitric oxide production.
Seidel
Bertolt
B
University Hospital for Children and Adolescents, Medical Faculty, University of Leipzig, Germany.
Bigl
Marina
M
Franke
Heike
H
Kittner
Holger
H
Kiess
Wieland
W
Illes
Peter
P
Krügel
Ute
U
D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D001069:Appetite Regulation / Q000502:physiology*; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D031204:Caloric Restriction; D003345:Corticosterone / Q000097:blood; D002149:Energy Intake / Q000502:physiology*; D005227:Fatty Acids / Q000097:blood; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D020738:Leptin / Q000097:blood / Q000235:genetics; D009474:Neurons / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D015398:Signal Transduction / Q000502:physiology; D014280:Triglycerides / Q000097:blood
D005227:Fatty Acids; D020738:Leptin; C546384:P2ry1 protein, rat; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D014280:Triglycerides; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D052248:Nitric Oxide Synthase Type I; D003345:Corticosterone