Download PDF
Horm Metab Res 2002; 34(4): 207-211
DOI: 10.1055/s-2002-26711
Original Clinical

© Georg Thieme Verlag Stuttgart · New York

The Opposite Effects of Short- and Long-Term Salt Loading on Pituitary Adrenal Axis Activity in Rats

L.  L. K.  Elias 1 , A.  Dorival Campos 2 , A.  C.  Moreira 1
  • 1 Division of Endocrinology, Department of Medicine, School of Medicine of Ribeirao Preto, University of Sao Paulo, Brazil
  • 2 Department of Social Medicine, School of Medicine of Ribeirao Preto, University of Sao Paulo, Brazil
Further Information

Publication History

7 August 2001

6 December 2001

Publication Date:
30 April 2002 (online)

Also available at
    Permissions and Reprints

Abstract

Osmotic stimulation has been shown to modify corticotropin responsiveness. We compared the effects of short- and long-term salt loading on pituitary-adrenal activity in control rats receiving tap water and rats submitted to salt loading for 1 day (S1) or 8 days (S8). Corticosterone (B) and adrenocorticotropic hormone (ACTH) plasma levels were determined at 8 a. m. under basal conditions or after immobilization stress for 15 min or corticotropin-releasing hormone (CRH) stimulation. S1 rats showed a similar ACTH response to immobilization, but an increased CRH response. In contrast, S8 rats showed blunted responses after immobilization or CRH stimulation. To evaluate the circadian variation of this inhibitory effect on the stress in the S8 group, immobilization was also performed at 8 p. m. Plasma ACTH and B levels under resting conditions were higher at 8 p. m. than 8 a. m. (p < 0.05) in control and S8 rats. The ACTH response to immobilization in the S8 group was lower than control at both 8 a. m. and 8 p. m. (p < 0.05); however, this reduction was more evident the morning, resulting in an inversion of the diurnal pattern with a higher ACTH response at 8 p. m. In conclusion, short osmotic stimulation results in an increased pituitary response to CRH, whereas prolonged stimulation decreases the pituitary response to CRH and immobilization, showing an interaction between osmoregulation and hypothalamus-pituitary-adrenocortical activity.

Key words

ACTH - Corticosterone - Osmotic Stimulus - CRH - Stress - Rhythm

References

  • 1 Whitnall M H, Mezey E, Gainer H. Co-localization of corticotropin-releasing factor and vasopressin in median eminence neurosecretory vesicles.  Nature. 1985;  317 248-250
    CrossrefPubMedGoogle Scholar
  • 2 Gillies G, Lowry P. Corticotropin-releasing factor may be modulated by vasopressin.  Nature. 1979;  278 463-464
    PubMedGoogle Scholar
  • 3 Rivier C, Vale W. Interaction of corticotropin-releasing factor and arginine vasopressin on adrenocorticotropin secretion in vivo. .  Endocrinology. 1983;  113 939-942
    PubMedGoogle Scholar
  • 4 Rivier C, Rivier J, Mormede P, Vale W. Studies of the nature of the interaction between vasopressin and corticotropin-releasing factor on adrenocorticotropin release in the rat.  Endocrinology. 1984;  15 883-886
    PubMedGoogle Scholar
  • 5 Whitnall M H, Key S, Gainer H. Vasopressin-containing and vasopressin-deficient subpopulations of corticotropin-releasing factor axons are differentially affected by adrenalectomy.  Endocrinology. 1987;  120 2180-2182
    PubMedGoogle Scholar
  • 6 Aguilera G. Regulation of pituitary secretion during chronic stress.  Front Neuroendocrinol. 1994;  15 321-350
    CrossrefPubMedGoogle Scholar
  • 7 Ma X M, Lightman S L. The arginine vasopressin and corticotropin-releasing hormone gene transcription responses to varied frequencies of repeated stress in rats.  J Physiol. 1998;  510 605-614
    CrossrefPubMedGoogle Scholar
  • 8 Antoni F A. Vasopressinergic control of pituitary adrenocorticotropin secretion comes of age.  Front Neuroendocrinol. 1993;  14 76-122
    PubMedGoogle Scholar
  • 9 Bias L LK, Antunes-Rodrigues J, Elias P CL, Moreira A C. Effect of plasma osmolality on pituitary-adrenal responses to corticotropin-releasing hormone and atrial natriuretic peptide changes in central diabetes insipidus.  J Clin Endocrinol Metab. 1997;  82 1243-1247
    CrossrefPubMedGoogle Scholar
  • 10 Dohanics J, Kovacs K J, Folly G, Makara G B. Long-term salt loading impairs pituitary responsiveness to ACTH secretagogues and stress in rats.  Peptides. 1990;  11 59-63
    CrossrefPubMedGoogle Scholar
  • 11 Jessop D S, Chowdrey H S, Lightman S L. Inhibition of rat corticotropin-releasing factor and adrenocorticotropin secretion by an osmotic stimulus.  Brain Res. 1990;  523 1-4
    CrossrefPubMedGoogle Scholar
  • 12 Chowdrey H S, Jessop D S, Patel H, Lightman S L. Altered adrenocorticotropin, corticosterone and oxytocin responses to stress during chronic salt load.  Neuroendocrinology. 1991;  54 635-638
    PubMedGoogle Scholar
  • 13 Aguilera G, Lightman S L, Kiss A. Regulation of the hypothalamic-pituitary-adrenal axis during water deprivation.  Endocrinology. 1993;  132 241-248
    CrossrefPubMedGoogle Scholar
  • 14 Kant G J, Mougey E H, Meyerhoff J L. Diurnal variation in neuroendocrine responses to stress in rats: plasma ACTH, β-endorphin, β-LPH, corticosteronne, prolactin and pituitary cyclic AMP responses.  Neuroendocrinnology. 1986;  43 383-390
    PubMedGoogle Scholar
  • 15 Bradbury M J, Cascio C S, Scribner K A, Dallman M F. Stress-induced adrenocorticotropin secretion: diurnal responses and decreases during stress in the evening are not dependent on corticosterone.  Endocrinology. 1991;  128 680-688
    PubMedGoogle Scholar
  • 16 Dallman M F, Akana S F, Scribner K A, Bradbury M J, Walker C D, Strack A M, Cascio C S. Stress, feedback and facilitation in the hypothalamo-pituitary-adrenal axis.  J Neuroendocrinol. 1992;  4 517-526
    PubMedGoogle Scholar
  • 17 Leal A MO, Moreira A C. Feeding and the diurnal variation of the hypothalamic-pituitary-adrenal axis and its responses to CRH and ACTH in rats.  Neuroendocrinology. 1996;  64 14-19
    PubMedGoogle Scholar
  • 18 López-Jiménez M, Valenca M M, Moreira A C, Antunes-Rodrigues J. Ether and immobilization stress effects on pituitary-adrenal function in hemidecorticated rats.  Braz J Med Biol Res. 1989;  22 779-782
    PubMedGoogle Scholar
  • 19 Moreira A C, Barizon E A, Sirva J R. Montagem e padronização do radioimunoensaio do ACTH plasmático.  Arq Bras Endocrinol Metab. 1987;  31 19-22
    PubMedGoogle Scholar
  • 20 Vinson G P, Hinson J P, Tóth I E. The neuroendocrinology of the adrenal cortex.  J Neuroendocrinol. 1994;  6 235-246
    PubMedGoogle Scholar
  • 21 Watts A G. Disturbance of fluid homeostasis leads to temporally and anatomically distinct responses in neuropeptide and tyrosine hydroxylase mRNA levels in the paraventricular and supraoptic nuclei of the rat.  Neuroscience. 1992;  46 859-879
    CrossrefPubMedGoogle Scholar
  • 22 Bartanusz V, Aubry J M, Jezova D, Baffi J, Kiss J Z. Up-regulation of vasopressin mRNA in paraventricular hypophysiotrophic neurons after acute immobilization stress.  Neuroendocrinology. 1995;  58 625-629
    PubMedGoogle Scholar
  • 23 Herman J P. In situ hybridization analysis of vasopressin gene transcription in the paraventricular and supraoptic nuclei of the rat regulation by stress and glucocorticoids.  J Compar Neural. 1995;  363 15-27
    PubMedGoogle Scholar
  • 24 Lang R E, Heil J, Ganten D, Hermann K, Unger T, Rascher W. Oxytocin unlike vasopressin is a stress hormone in the rat.  Neuroendocrinology. 1983;  37 314-316
    PubMedGoogle Scholar
  • 25 Gibbs D M. Dissociation of oxytocin, vasopressin and corticotropin secretion during different types of stress.  Life Sti. 1984;  31 487-491
    PubMedGoogle Scholar
  • 26 Leal A MO, Forsling M L, Moreira A C. Diurnal variation of the pituitary-adrenal and AVP responses to stress in rats under food restriction.  Life Sci. 1995;  56 191-198
    CrossrefPubMedGoogle Scholar
  • 27 Jessop D S. Central non-glucocorticoid inhibitors of the hypothalamo-pituitary-adrenal axis.  J Endocrinol. 1999;  160 169-180
    CrossrefPubMedGoogle Scholar
  • 28 Aguilera G. Corticotropin releasing hormone, receptor regulation and the stress response.  Trends Endocrinol Metab. 1998;  9 329-336
    PubMedGoogle Scholar
  • 29 Hashiguchi H, Ye S H, Morris M, Alexander N. Single and repeated environmental stress: effect on plasma oxytocin, corticosterone, catecholamines, and behavior.  Physiol Behav. 1997;  61 731-736
    CrossrefPubMedGoogle Scholar
  • 30 Kovacs K J, Sawchenko P E. Mediation of osmoregulatory influences on neuroendocrine corticotropin-releasing factor expression by the ventral lamina terminalis.  Proc Natl Acad Sci USA. 1993;  90 7681-7685
    PubMedGoogle Scholar
  • 31 Imaki T, Vale W, Sawchenko P E. Regulation of corticotropin-releasing factor mRNA in neroendocrine and autonomic neurons and autonomic neurons by osmotic stimulation and volume loading.  Neuroendocrinology. 1992;  56 633-640
    PubMedGoogle Scholar
  • 32 Aguilera G, Pham Q, Rabadan-Diehl C. Regulation of pituitary vasopressin receptors during chronic stress: relationship to corticotroph responsiveness.  J Neuroendocrinol. 1994;  6 299-304
    PubMedGoogle Scholar
  • 33 Akana S F, Cascio C S, Du J Z, Levin N, Dallman M F. Reset of feedback in the adrenocortical system: an apparent shift in sensitivity of adrenocorticotropin to inhibition by corticosterone between morning and evening.  Endocrinology. 1986;  119 2325-2332
    PubMedGoogle Scholar

L. L. K. Elias

Departamento de Clínica Médica ·

Faculdade de Medicina de Ribeirao Preto · USP

14049-900 ·Ribeirao Preto - SP · Brasil ·

Phone: + 55 (16) 602 22 54

Fax: + 55 (16) 633 11 44 ·

Email: Ilelias@hotmail.com