Pituitary responses

FABER K A, HUGHES c L JR. (1993) Dose-responsive characteristics of neonatal exposure to genistein on pituitary responsiveness to gonadotrophin releasing hormone and volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) in postpubertal castrated female rats. Reprod Toxicol. 1 35-9. 

Henderson SR, Baker C, Fink G (1977) Oestradiol-17beta and pituitary responsiveness to luteinizing hormone releasing factor in the rat a study using rectangular pulses of oestradiol-17 beta monitored by non-chromatographic radioimmunoassay. J Endocrinol 73 441-453... 

Speight A, Popkin R, Watts AG, Fink G (1981) Oestradiol-17/3 increases pituitary responsiveness by a mechanism that involves the release and the priming effect of luteinizing hormone releasing factor. J Endocrinol 88 301-308... 

Intramuscular injection of turpentine causes a biphasic HPA response [33], The first phase corresponds to the stress of injection with no detectable changes in plasma IL-6 concentrations. However, the second phase coincides with an inflammatory response to the turpentine, a response accompanied by increased plasma ACTH, corticosterone, and IL-6 levels. CRH, AVP, and PGs play stimulatory roles in this model, whereas nitric oxide dampens the pituitary response [33], IL-ip may be important for triggering the release of these signaling molecules, since mice lacking the gene for IL-ip have a blunted GC response to turpentine [34],... 

Deuster PA, Faraday MM, Chrousos GP, Poth MA. Effects of dehydroepiandrosterone and alprazolam on hypothalamic-pituitary responses to exercise. J Chn Endocrinol Metab 2005 90(8) 4777-83. 

Masala A, Meloni T, Alagna S, Rovasio PP, Mele G, Franca V. Pituitary responsiveness to gonadotrophinreleasing and thyrotrophin-releasing hormones in children receiving phenobarbitone. BMJ 1980 281(6249) 1175-7. 

Macphee GJ, Larkin JG, Butler E, Beastall GH, Brodie MJ. Circulating hormones and pituitary responsiveness in young epileptic men receiving long-term antiepileptic medication. Epilepsia 1988 29(4) 468-75. 

Strohle A, Wiedemann K. Flumazenil attenuates the pituitary response to CRH in healthy males. Eur Neuropsychopharmacol 1996 6(4) 323-5. 

Wise, P.M. (1984). Estradiol-induced daily luteinizing hormone and prolactin surges in young and middle-aged rats Correlations with age-related changes in pituitary responsiveness and catecholamine turnover rates in microdissected brain areas. Endocrinology, 115 801-809. 

Bookstaff RC, Kamel F, Moore RW, et al. 1990b. Altered regulation of pituitary gonadotropin-releasing hormone (GnRH) receptor number and pituitary responsiveness to GnRH in 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated male rats. Toxicol Appl Pharmacol 105 78-92. 

Challenge tests Releasing hormone challenge tests to test pituitary responsiveness to hypothalamic hormones (GnRH, corticotropin releasing hormone, thyroid releasing hormone)... 

Blocked Hamster. Biol of Reprod 25 298-302 Adams TE, Norman RL, Spies HG (1981) Gonadotropin-Releasing Hormone Receptor Binding and Pituitary Responsiveness in Estradiol-Primed Monkeys. Science 213 1388-1390... 

The method of testing in vitro on dispersed pituitary cells is essentially a static method for the comparison of hormones and hormone analogs. It has also been applied to the testing and pituitary tissue ex vivo, from animals that have undergone a period of treatment with compounds that are known to modify the pituitary response, e.g. synthetic corticoids. 

Corticotropin activity can be measured by the increase of corticosterone in venous blood of hypophysec-tomized or dexamethasone-blocked rats, as a singledose test when receptor affinity for ACTH receptor is found with a test compound. The test can be used to measure time-response curves of corticotropin preparations, and compounds with a adrenal stimulating activity (Vogel 1969a,b). The use of hypophysec-tomized rats for evaluation of the pituitary response... 

Pease K, Shen H, Acres GS, Rupnow JH, Dixon JE (1980) Alterations in levels of thyrotrophin releasing hormone and rates of hormone degradation in hypothalamic tissue of the developing rat. J Endocrinol 85(1) 55—61 Queen G, Vivian S, LaBella F (1975) Monolayer cultures of dispersed cells from bovine anterior pituitary responses to synthetic hypophysiotropic peptides. Can J Physiol Pharmacol 53(6) 1094-8... 

The TSH radioimmunoassays procedures have replaced other methods for the quantitative assessment of changes in pituitary responsiveness after repeated dose treatment, test compounds which enhance the secretion of thyroid hormones lead to a suppression of the serum TSH concentrations, a clinical example being hyperthyroidism (Connors et al. 1981, Pekary et al. 1980). On the other hand, a reduction in circulating concentrations of thyroid hormones (T3 and T4) will release the pituitary gland from feedback inhibition, and the serum concentration of TSH may arise in an exponential manner. 

The anterior pituitary response to injury has now been examined in detail by means of radioimmunoassays. 

Brinsko S P, Squires E L, Pickett B W et al 1998 Gonadal and pituitary responsiveness of stallions is not down-regulated by prolonged pulsatile administration of GnRH. Journal of Andrology 19 100-109... 

Corticorelin. Corticorelin (Acthrel) is a synthetic pep-llde that may be used as an injectable in the determination of pituitary responsiveness. It pos.sesses the amino acid sequence found in corticotropin-releasing hormone that is responsible for stimulating the relea.se of ACTH. 

L10. Lim, V. L., Kathpatia, S. C., Frohman, L. A., et ai, Hyperprolactinemia and impaired pituitary response to suppression and stimulation in chronic renal failure Reversal after transplantation. J. Clin. Endocrinol. Metab. 48, 101-107 (1979). 

Fig. 3 Pituitary responses to TRH. (a) Used in the investigation of hyperthyroidism, (b) Used in the investigation of hypothyroidism.

Fig. 8.3. Pituitary response to continuous or pulsatile stimulation by the hormone GnRH in the rhesus monkey. In (a), the continuous infusion of GnRH at four different rates fails to induce proper secretion of LH and of FSH. In contrast, pulsatile infusion of GnRH (b) in the form of 1 mg/min for 6 min every hour induces appropriate secretion of the gonadotropic hormones by the pituitary (Belchetz etal., 1978).

Martha, P.A. Jr, R.M. Blizzard, J.A. McDonald, M.O. Thorner A.D. Rogol. 1988. A persistent pattern of varying pituitary responsivity to exogenous growth hormone (GH)-releasing hormone in GH-deficient children Evidence supporting periodic somatostatin secretion. J. Clin. Endocrinol. Metab. 67 449-54. 

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