Vasopressin and galanin expression in the hypothalamus of two African rodents, Taterillus gracilis and Steatomys caurinus, subjected to water-restriction.
The expression of arginine-vasopressin (AVP) and galanin (GAL) was studied by immunohistochemistry and in situ hybridization in the hypothalamus of two species of African rodents. In the wild, these animals experience successive arid and wet seasons that alternately stimulate their antidiuretic and diuretic systems. In this study, animals were subjected to both standardized laboratory conditions and to eight days of water-restriction. Under both sets of conditions, AVP and GAL were detected in the supraoptic nucleus (SON), paraventricular nucleus (PVN), and median eminence (ME). AVP and GAL responses to water-restriction differed in the two species, as did behavioral adaptations to the hot-dry season. In Taterillus gracilis, AVP- and GAL-LI (like immunoreactivity) peptide and mRNA levels increased in the SON. AVP-LI peptide and mRNA levels increased in the PVN, whereas only AVP-LI peptide levels increased in the ME. Pituitary gland AVP pools were unchanged by water deprivation, whereas urinary AVP levels and osmolality increased. The AVP response is typical of that of desert rodents, favoring survival under conditions of water-restriction. In Steatomys caurinus, which estivates, AVP and GAL-LI peptide levels decreased in the hypothalamus, as they did in the laboratory rat. In the SON, AVP, and GAL mRNA levels increased, whereas, in the PVN, only AVP mRNA levels increased. Pituitary gland AVP levels decreased, whereas urinary AVP levels and osmolality increased. In both species, the changes in the amount of GAL-LI peptide appeared to be closely linked to changes in AVP levels, suggesting that this peptide is involved in the osmoregulatory response to water-restriction.
Lacas-Gervais
S
S
Neurobiologie des Signaux Intercellulaires, UMR7101 CNRS, Université Paris 6, 7 quai Saint Bernard, case 002, 75252 Paris Cedex 05, France.
Maurel
D
D
Hubert
F
F
Allevard
A M
AM
Doukary
A
A
Maggi
V
V
Siaud
P
P
Gharib
C
C
Sicard
B
B
Calas
A
A
Hardin-Pouzet
H
H
D000349:Africa; D000818:Animals; D001127:Arginine Vasopressin / Q000235:genetics / Q000378:metabolism* / Q000652:urine; D001835:Body Weight; D019004:Galanin / Q000235:genetics / Q000378:metabolism*; D006400:Hematocrit; D007031:Hypothalamus / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D009994:Osmolar Concentration; D010902:Pituitary Gland / Q000378:metabolism; D010949:Plasma / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012377:Rodentia / Q000378:metabolism*; D013194:Staining and Labeling; D014018:Tissue Distribution; D014556:Urine / Q000737:chemistry; D014868:Water Deprivation / Q000502:physiology*
D012333:RNA, Messenger; D001127:Arginine Vasopressin; D019004:Galanin