Gonadectomy Reverses The Sexually Diergic Patterns Of Circadian and Stress‐Induced Hypothalamic‐Pituitary‐Adrenal Axis Activity In Male and Female Rats
Tóm tắt
Enhanced corticosterone release by female compared to male rats under basal and stress conditions is well documented. The demonstration that gonadectomy enhances stress‐induced corticosterone secretion in male rats, but reduces such levels in female rats, suggests a causal association between gonadal steroids and corticosterone release. The present study examined the corticosterone profile of sham gonadectomized and gonadectomized female and male rats under basal and stress conditions. An automated sampling system collected blood from each freely moving, unanaesthetized rat every 10 min (i) over a 24‐h period; (ii) following noise stress; and (iii) following an immune‐mediated stress (lipopolysaccharide, LPS). Plasma was analysed for corticosterone content using radioimmunoassay. Castration resulted in a significant increase in basal corticosterone release compared to the sham‐castrated male rats. Pulsar analysis revealed a significant two‐fold increase in the number of corticosterone pulses over 24 h. Corticosterone increases in response to noise stress and to LPS injection were enhanced following castration. Conversely, ovariectomy resulted in a two‐fold reduction in the number of corticosterone pulses as well as the stress response compared to sham‐ovariectomized female rats. Arginine vasopressin (AVP), corticotrophin‐releasing hormone (CRH) and glucocorticoid receptor mRNAs in the paraventricular nucleus and pro‐opiomelanocortin (POMC) mRNA in the anterior pituitary were analysed post‐LPS administration by
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Tài liệu tham khảo
Veldhuis JB, 1989, Amplitude modulation of a burst like mode of cortisol secretion subserves the circadian glucocorticoid rhythm, Am J Physiol, 257, E6
Harbuz MS, 1997, Steroid Hormones and the T‐Cell Cytokine Profile.
Critchlow V, 1963, Sex differences in resting pituitary‐adrenal function in the rat, Am J Physiol, 205, 807, 10.1152/ajplegacy.1963.205.5.807
Viau V, 1991, Individual differences in the hypothalamic‐pituitary‐adrenal response to stress: relationship to testosterone, Soc Neurosci Abstract, 17, 542
Atkinson HC, 1997, Circadian variation in basal plasma corticosterone and adrenocorticotropin in the rat: sexual dimorphism and changes across the estrous cycle, Endocrinology, 9, 3842, 10.1210/endo.138.9.5395
Patchev VK, 1995, Implications of estrogen dependent brain organisation for gender differences in hypothalamo‐pituitary‐adrenal regulation, FASEB, 9, 419, 10.1096/fasebj.9.5.7896013
Bingaman EW, 1994, Neuroendocrinology, 228
Takahashi H, 1983, POMC probe, Nucl Acid Res, 11, 6647
Merriam GR, 1982, Algorhythms for the study of episodic hormone secretion, Am J Physiol, 243, E310
Festing MFW, 2002, The Design of Animal Experiments
Buckingham JC, 1997, Stress, Stress Hormones and the Immune System