Vitamin A regulates hypothalamic-pituitary-adrenal axis status in LOU/C rats

J Endocrinol. 2013 Sep 6;219(1):21-7. doi: 10.1530/JOE-13-0062. Print 2013 Oct.

Abstract

The aim of this study was to explore the involvement of retinoids in the hypoactivity and hyporeactivity to stress of the hypothalamic-pituitary-adrenal (HPA) axis in LOU/C rats. We measured the effects of vitamin A deficiency administered or not with retinoic acid (RA) on plasma corticosterone in standard conditions and in response to restraint stress and on hypothalamic and hippocampal expression of corticosteroid receptors, corticotropin-releasing hormone and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in LOU/C rats. Interestingly, under control conditions, we measured a higher plasma concentration of retinol in LOU/C than in Wistar rats, which could contribute to the lower basal activity of the HPA axis in LOU/C rats. Vitamin A deficiency induced an increased HPA axis activity in LOU/C rats, normalized by RA administration. Compared with LOU/C control rats, vitamin A-deficient rats showed a delayed and heightened corticosterone response to restraint stress. The expression of corticosteroid receptors was strongly decreased by vitamin A deficiency in the hippocampus, which could contribute to a less efficient feedback by corticosterone on HPA axis tone. The expression of 11β-HSD1 was increased by vitamin A deficiency in the hypothalamus (+62.5%) as in the hippocampus (+104.7%), which could lead to a higher production of corticosterone locally and contribute to alteration of the hippocampus. RA supplementation treatment restored corticosterone concentrations and 11β-HSD1 expression to control levels. The high vitamin A status of LOU/C rats could contribute to their low HPA axis activity/reactivity and to a protective effect against 11β-HSD1-mediated deleterious action on cognitive performances during ageing.

Keywords: LOU/C; glucocorticoid; rat; retinol; stress.

MeSH terms

  • 11-beta-Hydroxysteroid Dehydrogenase Type 1 / biosynthesis
  • Animals
  • Corticosterone / blood
  • Corticotropin-Releasing Hormone / biosynthesis
  • Hypothalamo-Hypophyseal System / drug effects*
  • Hypothalamo-Hypophyseal System / physiology
  • Male
  • Pituitary-Adrenal System / drug effects*
  • Pituitary-Adrenal System / physiology
  • Rats
  • Rats, Inbred Strains
  • Rats, Wistar
  • Stress, Physiological
  • Stress, Psychological / physiopathology
  • Tretinoin / therapeutic use
  • Vitamin A / blood
  • Vitamin A / pharmacology*
  • Vitamin A Deficiency / drug therapy
  • Vitamin A Deficiency / metabolism
  • Vitamin A Deficiency / physiopathology

Substances

  • Vitamin A
  • Tretinoin
  • Corticotropin-Releasing Hormone
  • 11-beta-Hydroxysteroid Dehydrogenase Type 1
  • Corticosterone