Effects of food deprivation on midbrain 5-HT1A autoreceptors in Lewis and SHR rats.
Food deprivation stimulates the activity of the hypothalamo-pituitary-adrenal axis and brain serotonin (5-hydroxytryptamine, 5-HT) synthesis. Because midbrain somato-dendritic 5-HT1A autoreceptors may obey homologous and heterologous (e.g. by glucocorticoids) down-regulation, we have analyzed whether 24 hr of fasting affects midbrain 5-HT1A receptor binding and sensitivity in Lewis and SHR rats (i.e. strains that differ in behavioral/neuroendocrine responses to stressors). Fasting affected neither [3H]8-hydroxy-2-(di-N-propylamino)tetralin ([3H]8-OH-DPAT) binding at 5-HT1A autoreceptors nor 8-OH-DPAT-induced inhibition of midbrain 5-HT synthesis (an index of 5-HT1A autoreceptor sensitivity). Because fasting increased 5-HT precursor (tryptophan) levels to similar extents in the midbrains of saline- and 8-OH-DPAT-treated rats, we conclude that food deprivation does not affect 5-HT1A autoreceptors. In turn, our results suggest that the differential effects of 5-HT1A receptor agonists on food intake, in fed and fasted rats may be independent from 5-HT1A autoreceptors.
Chaouloff
F
F
INSERM CJF 94-05 INRA, Institut Francois Magendie, Bordeaux, France. francis.chaouloff@bordeaux.inserm.fr
Berton
O
O
Aquerre
S
S
Hay
M
M
Mormede
P
P
D006916:5-Hydroxytryptophan / Q000378:metabolism; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism; D000818:Animals; D004644:Emotions / Q000502:physiology; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D008636:Mesencephalon / Q000378:metabolism*; D051381:Rats; D011917:Rats, Inbred Lew; D011918:Rats, Inbred SHR; D011985:Receptors, Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000378:metabolism; D013045:Species Specificity; D014364:Tryptophan / Q000378:metabolism
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D014364:Tryptophan; D006916:5-Hydroxytryptophan