The Effect of Stress and Nembutal on Plasma Levels of Gonadotropins and Prolactin in Ovariectomized Rats

Ajika, K.; Kalra, Satya P.; Fawcett, C. P.; Krulich, L.; McCann, Samuel M.

doi:10.1210/endo-90-3-707

Cited by 145 publications

(83 citation statements)

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“…It has been reported that plasma concentrations of prolactin increased in response to acute and chronic stress (Ajika et al 1972, Euker et al 1975, Turpen et al 1976. In the present study, for both lines of Hatano rats, plasma concentrations of prolactin also increased under restraint stress.…”

Section: Discussionsupporting

confidence: 65%

Differential responses of the hypothalamo-pituitary-adrenocortical axis to acute restraint stress in Hatano high- and low-avoidance rats

Asai

Ohta²,

Shirota³

et al. 2004

Journal of Endocrinology

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The high-and low-avoidance animal (HAA and LAA respectively) strains of Hatano rats were originally selected and bred from Sprague-Dawley rats for their performance in the shuttle-box task. The present study focused on the activity of the hypothalamo-pituitary-adrenocortical (HPA) axis of HAA and LAA rats in response to restraint stress. The restraint stress induced an elevation in plasma concentrations of ACTH, prolactin, corticosterone and progesterone. Peak levels of plasma ACTH during stress conditions were significantly higher in HAA rats than in LAA rats, while peak levels of prolactin were significantly lower in HAA rats than in LAA rats. Under stress conditions, ACTH and prolactin synthesis in the anterior pituitary glands was significantly higher in HAA rats compared with LAA rats. The peak plasma concentrations of corticosterone, during restraint stress, were significantly higher in LAA rats compared with HAA rats. These results indicate that the response of the hypothalamo-pituitary axis to acute restraint stress is greater in HAA rats than in LAA rats, whereas the ACTH-induced adrenal response of corticosterone release is higher in LAA rats than in HAA rats. On the other hand, prolactin secretory activity is higher in LAA rats compared with HAA rats. These differences in endocrine responses to stress may be involved in the regulation of the avoidance responses in the shuttle-box task.

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Section: Discussionsupporting

confidence: 65%

Differential responses of the hypothalamo-pituitary-adrenocortical axis to acute restraint stress in Hatano high- and low-avoidance rats

Asai

Ohta²,

Shirota³

et al. 2004

Journal of Endocrinology

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“…The reasons for this are not clear but many stimuli have been shown to influence prolactin secretion in addition to the stage in the oestrous cycle or level of circulating ovarian hormones. In particular, mode of blood collection (Neill, 1972) and degree of ether stress (Ajika et al, 1972) influence plasma prolactin concentrations. This is confirmed by the present study.…”

Section: Discussionmentioning

confidence: 99%

Oestradiol-17β and prolactin levels in rat peripheral plasma

Hawkins¹,

Freedman²,

Marshall³

et al. 1975

Br J Cancer

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Summary.-Radioimmunoassay methods for the determination of oestradiol-17p and prolactin have been examined for their reliability and applied to the measurement of hormone concentrations in the plasmas from male and female rats. Prolactin was detectable in all samples (>7 ng RP-1 ng/ml) but the concentration of oestradiol-17p was below the sensitivity of the method (>0*10 ng /lOOml) in ovariectomized females. Plasma oestradiol-17p concentration rose gradrfally from metoestrus to proestrus and fell to barely detectable levels in oestrus. Plasma prolactin concentration was very variable even for rats in the same stage of the oestrous cycle but values were minimal in the afternoon of diestrus and a surge in secretion occurred in the afternoon of proestrus. In addition to the stage of the oestrous cycle, the prolactin concentration was influenced by mode of blood collection, degree of haemolysis and choice of serum or plasma. There was no correlation between the concentration of prolactin and that of oestradiol-17P in the same sample of plasma.IN THE RAT, the growth of experimental mammary tumours induced by the administration of the carcinogen 7,12-dimethylbenzanthracene (DMBA) has been reported to be influenced by both oestrogen (Dao and Sinha, 1972), and prolactin (Pearson, 1969). As a preliminary to an investigation of the role of these hormones in tumour growth, we have set up methods for their measurement by radioimmunoassay. The reliability of each method has been examined and the basal levels of each hormone have been measured at various stages during the oestrous cycle, in ovariectomized animals and in males. Although the fluctuations in plasma oestradiol-17/3 (Hori, Ide and Miyake, 1968;Yoshinaga, Hawkins and Stocker, 1969;Brown-Grant, Exley and Naftolin, 1970; Shaikh, 1971;Dupon and Kim, 1973), and plasma prolactin (Kwa and Verhofstad 1967; Niswender et al., 1968;Gay, Midgeley and Niswender, 1970;Amenomori, Chen and Meites, 1970;Neill and Reichert, 1971;Neill, 1972) during the oestrous cycle have been reported previously, the results of simultaneous measurements of both hormones in individual rats have not to our knowledge been published. MATERIALS AND METHODSAnimals.-Randomly bred SpragueDawley rats were maintained on a lighting; darkness schedule of 12 h L: 12 h D, with the lights switched on at 0700 hours. Vaginal smears were taken daily by lavage and the rats were followed for at least 2 cycles. Only rats with regular 4-day cycles were used and stage in the cycle was defined as previously described (Yoshinaga et al., 1969).Blood was withdrawn into a hepariniZed syringe from the abdominal aorta under ether anaesthesia except when otherwise stated. Blood samples were cooled in ice and the plasma was separated by centrifugation at 4 TC at approximately 1300 g. In one experiment, serum was prepared by the collection of non-heparinized blood, allowing the blood to clot for at least 2 h at 4 TC and centrifugation. Haemolysed plasma was prepared by the addition of water to heparinized blood

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“…The aortic cannulation of rats resulted in modified patterns of prolactin and LH secretion during the estrous cycle (Neill, 1972). Also, anesthetization and surgery were shown to affect hypophysial hormone secretion patterns (Ajika et al, 1972 ;Krvlich et at., 1974 ;Glass et al, 1978 ;Wang et al, 1978 (1977). Within-assay variability (the coefficient of variation of the values obtained for three plasma samples, each run several times in the same assay) was 0.10 (X = 1.39 ng GTH/ml, n = 4) and 0.07 (X = 6.53 ng GTH/ml, n = 6 and X = 18.08 ng GTH/ml, n = 6).…”

Section: Introductionmentioning

confidence: 99%

Dorsal aorta catheterization in rainbow trout (Salmo gairdneri). I. Its validity in the study of blood gonadotropin patterns

Zohar¹

1980

Reprod. Nutr. Dévelop.

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The Effect of Stress and Nembutal on Plasma Levels of Gonadotropins and Prolactin in Ovariectomized Rats

Cited by 145 publications

References 0 publications

Differential responses of the hypothalamo-pituitary-adrenocortical axis to acute restraint stress in Hatano high- and low-avoidance rats

Differential responses of the hypothalamo-pituitary-adrenocortical axis to acute restraint stress in Hatano high- and low-avoidance rats

Oestradiol-17β and prolactin levels in rat peripheral plasma

Dorsal aorta catheterization in rainbow trout (Salmo gairdneri). I. Its validity in the study of blood gonadotropin patterns

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