Pattern of Adenohypophyseal Hormone Changes Induced by Various Stressors in Female and Male Rats

Ruisseau, P. Du; Taché, Y.; Brazeau, Paul; Collu, R.

doi:10.1159/000122818

Cited by 81 publications

(25 citation statements)

References 10 publications

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“…Other studies reported both in creases [3,30] and decreases [31,32] in PRL after cold exposure, and these different findings may represent nonspecific effects since PRL respond rapidly to stress [31][32][33]. With regard to the cold-associated stimulation of the thyroid function, this response seems specific for the cold stress since other types of stress are known to reduce, rather than to increase, TSH levels [33].…”

Section: Discussionmentioning

confidence: 93%

Effect of Cold Exposure on the Hypothalamic Release of Thyrotropin-Releasing Hormone and Catecholamines

Rondeel

Greef²,

Hop³

et al. 1991

Neuroendocrinology

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The effects of cold exposure on the release of thyrotropin-releasing hormone (TRH) and catecholamines as estimated by push-pull perfusion of the mediobasal hypothalamus were studied. Before cold exposure, the male rats had been kept at room temperature or at 30 °C for 3 weeks. Transfer to 4 °C increased plasma levels of thyroid-stimulating hormone (TSH), but this cold-induced TSH response was more pronounced in animals which had been acclimatized to 30 ° C. Exposure to 4 ° C also increased plasma thyroid hormone levels, but had no effect on plasma prolactin. The hypothalamic content of TRH and dopamine remained similar after transfer to 4 ° C, but after 6 h of cold, the content of noradrenaline and adrenaline had increased 1.6-fold and 3-fold, respectively. In vivo hypothalamic release of TRH, adrenaline and dopamine remained similar during a 2-hour period in control rats kept at room temperature or 30 ° C. The hypothalamic release of TRH, dopamine and adrenaline did not change in rats transferred from room temperature to 4 ° C. The amount of dopamine and adrenaline in push-pull perfusate also remained similar in rats acclimatized to 30 °C after transfer to low temperatures. However, in these rats kept at 30 °C for 3 weeks, exposure to 4 ° C increased TRH release in perfusate from the mediobasal hypothalamus in the first 15 min of cold exposure (2-fold increase). Thus, exposure to cold stimulates the hypothalamo-pituitary-thyroid axis and increases the hypothalamic release of TRH in rats which had been acclimatized to 30 ^¤ C.

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Section: Discussionmentioning

confidence: 93%

Effect of Cold Exposure on the Hypothalamic Release of Thyrotropin-Releasing Hormone and Catecholamines

Rondeel

Greef²,

Hop³

et al. 1991

Neuroendocrinology

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“…TSH was also evaluated under basal and stress conditions in adult males, as immobilization stress has been reported to reduce the TSH levels in rodents [25, 26]. Both genotypes responded to immobilization stress with a similar decrease in TSH levels (fig.…”

Section: Resultsmentioning

confidence: 99%

“…We have previously reported that a suckling-induced TSH increase is abolished by baclofen administration in the rat [6], suggesting a participation of GABA B Rs in TSH regulation. In addition, stress was shown to influence the TSH secretion, increasing or decreasing its levels, depending on the stressor used [25, 26]. We, therefore, evaluated basal TSH levels and their response to immobilization stress in null mutant and wild-type mice.…”

Section: Discussionmentioning

confidence: 99%

GABA<sub>B1</sub> Knockout Mice Reveal Alterations in Prolactin Levels, Gonadotropic Axis, and Reproductive Function

et al. 2005

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γ-Aminobutyric acid (GABA) has been implicated in the control of hypophyseal functions. We evaluated whether the constitutive loss of functional GABA_B receptors in GABA_B1 knockout (GABA_B1^–/–) mice alters hormonal levels, under basal and stimulated conditions, and reproductive function. The serum hormone levels were measured by radioimmunoassay, the estrous cyclicity was evaluated by vaginal lavages, and the mating behavior was determined by the presence of vaginal plugs. A moderate hyperprolactinemic condition was observed, in which prolactin increase and thyroid-stimulating hormone decrease were similar between genotypes. Basal luteinizing hormone (LH), follicle-stimulating hormone, thyroid-stimulating hormone, and growth hormone levels were similar between genotypes in each sex. Analysis of the gonadotropin axis revealed no differences in puberty onset between female genotypes. In con trast, the estrous cyclicity was significantly disrupted in GABA_B1^–/– female mice, showing significantly extended periods in estrus and shortened periods in proestrus. Reproduction was significantly compromised in GABA_B1^–/– females, with a significantly lower proportion of mice (37.5%) getting pregnant during the first 30 days of mating as compared with wild-type controls (87.5%). Moreover, only 14% of vaginal plug positive GABA_B1^–/– females had successful pregnancies as compared with 75% in the controls. In addition, the postovariectomy LH rise was significantly advanced in GABA_B1^–/– mice, while the response to estradiol feedback was similar in both genotypes. In conclusion, our endocrine analysis of GABA_B1^–/– mice reveals that GABA_B receptors are involved in the regulation of basal prolactin titers. Moreover, the hypothalamic-hypophyseal-ovarian axis is seriously disturbed, with alterations in cyclicity, postcastration LH increase, and fertility indexes. The molecular mechanism underlying these hormonal disturbances remains to be addressed.

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“…In sub-mammalian species also, n petitive presentation of the same stressor over a long perio resulted in gradual diminution of the plasma corticoid ris e.g., Salmo irrideus, Rana esculenta. Anas platyrhynchos [13 However, other workers did not find any change in th magnitude of the corticosteroid response during repeated exposure to a stressor in mammals [9,12,27] or in birds |-11], In this respect, it is interesting to note that in rats adapted to traumatization in a Noble-Collip drum, the magnitude of the adrenocortical reaction immediately after injury was as high as in non-adapted controls. However, their increased plasma corticosterone level returned more rapidly to the basal value after injury [15].…”

Section: Discussionmentioning

confidence: 96%

Adaptation of the Adrenocortical Response during Repeated Stress in Thalamic Pigeons

Ramade¹,

Baylé²

1984

Neuroendocrinology

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Chronic vascular catheterization allowed to obtain serial blood samples before and after stress application to thalamic pigeons. Daily repetition of the same stress, at the same hour, for 5 weeks led to drastic changes in the stress-induced adrenocortical reaction. The rebounding, long-lasting rise in plasma corticosterone occurring after initial presentation of electrical footshocks was replaced by a single peak of corticosterone, lower and shorter than the initial response. Moreover, an anticipatory conditioned rise in corticosterone appeared before stress. Random distribution of stressful stimuli, thrice a day, for 5 weeks resulted in the single peak pattern of post-stress adrenocortical reaction, without any anticipatory component. When electrical footshocks were omitted after 5 weeks of daily regular presentation of stress, only the anticipatory peak in plasma corticosterone occurred. Shifting the daily lighting from the usual 06.00 a.m. to 04.00 a.m. led to a shift in the anticipatory conditioned endocrine response which appeared 2 h sooner than usual. Thalamic involvement in the process of adaptation to chronic stress is discussed.

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Pattern of Adenohypophyseal Hormone Changes Induced by Various Stressors in Female and Male Rats

Cited by 81 publications

References 10 publications

Effect of Cold Exposure on the Hypothalamic Release of Thyrotropin-Releasing Hormone and Catecholamines

Effect of Cold Exposure on the Hypothalamic Release of Thyrotropin-Releasing Hormone and Catecholamines

GABA<sub>B1</sub> Knockout Mice Reveal Alterations in Prolactin Levels, Gonadotropic Axis, and Reproductive Function

Adaptation of the Adrenocortical Response during Repeated Stress in Thalamic Pigeons

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