Disease relevance of Hypophysectomy

• PURPOSE: The present study was designed to determine whether these in vitro observations could be extended to an in vivo experimental system and whether reduction of IGF-I levels by hypophysectomy could inhibit the aggressive metastatic behavior of osteosarcoma [1].
• The presence of an entirely extrasellar ACTH-releasing adenoma in the cavernous sinus could explain why pituitary-dependent Cushing's disease may persist postoperatively, even after total hypophysectomy [2].
• Out of 4 GH producing pituitary adenomas obtained from patients with active acromegaly at hypophysectomy two were stimulated by TRH, two by LH-RH, three by norepinephrine, one by dopamine, four by PGE1 and none by serotonin [3].
• A defect in the synthesis or release of CRF has been implicated in the development of obesity in laboratory animals, since the condition is alleviated by adrenalectomy, hypophysectomy or exogenous CRF treatment [4].
• The results suggest that the hypophysectomy and thyroxine treatment of the host rat might selectively influence the production of hormones by the MtT-F4 transplantable rat pituitary tumor [5].

Psychiatry related information on Hypophysectomy

• In control rats, hypophysectomy was followed by a 35.7% decrease in paradoxical sleep (PS) duration while it has no effect on the sleep of MSG-treated rats [6].
• Feeding behavior elicited by injection of norepinephrine (NE) into the paraventricular nucleus (PVN) of satiated rats has been shown to be abolished by hypophysectomy [7].

High impact information on Hypophysectomy

• Hypophysectomy of adult male rats abolishes alpha 2u globulin synthesis; synthesis can be fully restored by daily administration of androgen, thyroid hormone, glucocorticoid and growth hormone for 12 days [8].
• Sertoli cell secretory function after hypophysectomy [9].
• Hypophysectomy triggered an abrupt decrease in the proportion of Slo transcripts containing a "STREX" exon [10].
• The inhibitory effect of CRF was blocked by vagotomy and adrenalectomy but not by hypophysectomy or naloxone treatment [11].
• Denervation and hypophysectomy block the increase in medullary and cortical enzyme activity, respectively, whereas cycloheximide presents the increase in both tissues [12].

Chemical compound and disease context of Hypophysectomy

• Human PRL (hPRL)-secreting adenoma cells obtained at hypophysectomy were fused with a mutant mouse fibroblast line (LMTK-) which is aminopterin sensitive due to a deficiency in the enzyme thymidine kinase [13].
• The effects of hormones and hormone-like substances such as thyroxine, estradiol, hydrocortisone, calcitonin, prostaglandins (F2a, A2) or hormone deficiency (hypophysectomy, gonadectomy) on the development of carcinomas in mice and rats induced by 3-methylcholanthrene were investigated [14].
• The diabetes + hypophysectomy animals maintained their body weight better, did not have hypertrophied adrenal glands, showed the least elevation of serum enzymes, e.g., CPK, SGOT, SGPT and LDH, less hyperlipidemia and hyperglycemia and reduced corticosterone production than the animals with untreated severe diabetes [15].
• Surgical hypophysectomy by decapitation of the fetus 3 days before death produced a reduction of LH activity in plasma and level of testosterone in the testes; the development of cranial prostatic buds was impaired although plasma levels of testosterone were unchanged [16].
• 2. Growth was arrested in young rats (less than 100 g body weight) by hypophysectomy and stimulated by the administration of growth hormone or triiodothyronine [17].

Biological context of Hypophysectomy

• DNA synthesis and mitosis in frog lens epithelium are abolished by hypophysectomy and restored by somatomedin C [18].
• Despite the hypophysectomy, E2 stimulated some, albeit blunted, mammary growth and development, which may have been due to incomplete hypophysectomy [19].
• Mean cell volume and cell height were significantly reduced by hypophysectomy at the proliferative and hypertrophic stages, but were restored to physiological values by IGF-I and GH [20].
• However, hypophysectomy alone completely eliminated this cell-specific component of KAP gene expression [21].
• The spectrum of the effects of cis-platinum on cytochrome P-450-dependent drug metabolism and steroid hydroxylation activity mimic those produced by hypophysectomy and are for the most part reversed by the anterior pituitary hormones [22].

Anatomical context of Hypophysectomy

• The neuronal storage of a prolactin-like protein in the hypothalamus was unaffected by hypophysectomy [23].
• Cyclic AMP and cyclic GMP were measured in rat adrenal glands after either hypophysectomy alone or after hypophysectomy and treatment with ACTH [24].
• Pituitary ablation (hypophysectomy) in rats was previously reported to cause a precipitous change in the relative abundance of two alternative splice variants of the "BK"- or "Maxi K"-encoding Slo gene in adrenal chromaffin cells [25].
• In the adrenal, pineal, striatum, and midbrain, SAM levels fell after hypophysectomy and were restored by dexamethasone administration [26].
• In the rat testis, 7 days after hypophysectomy, the microsomal content of cytochrome P-450 decreased to a negligible level [27].

Associations of Hypophysectomy with chemical compounds

• Hypophysectomy diminished receptor levels in the female and rendered males unresponsive to estrogen [28].
• Somatomedin-like activity in frog serum is diminished by hypophysectomy and is restored by growth hormone and triiodothyronine [18].
• Therefore, frequent monitoring of the blood glucose level is necessary in all acromegalic patients following hypophysectomy, even if they are euglycemic prior to surgery [29].
• Moreover, hypophysectomy results in a marked increase in sensitivity of mice to endotoxin challenge as well as an abrogation of the protection against endotoxin lethality mediated by hydrazine sulfate [30].
• In addition to determining the effect of hydrazine sulfate on the plasma levels of phosphoenolpyruvate carboxykinase regulating hormones, we have investigated the effects of hydrazine sulfate on endotoxin lethality in mice whose capacity to respond hormonally to external stimuli has been compromised by hypophysectomy [30].

Gene context of Hypophysectomy

• Vasoactive intestinal polypeptide (VIP)- and peptide histidine-isoleucine (PHI)-IR fibers in hypophysectomized animals had already contacted portal vessels 5 d after hypophysectomy, and from then on progressively increased in numbers [31].
• Hypophysectomy (HPX) produced a 3-5-fold decrease in Star mRNA along with a loss of adrenal steroids, whereas P450scc mRNA decreased by less than 2-fold [32].
• The three serine protease inhibitor (SPI) rat genes expressed preferentially in liver share considerable structural features and, nonetheless, are transcriptionally regulated in completely different manners, more particularly after hypophysectomy or upon acute inflammation [33].
• Second, hypophysectomy disrupted basal activation of Stat5, an effect that was completely reversed by administration of PRL, but only partially by GH [34].
• We reported earlier that in adult rats, HNF-6 mRNA concentration in liver drops to almost undetectable levels after hypophysectomy and returns to normal after 1 week of GH treatment [35].

Analytical, diagnostic and therapeutic context of Hypophysectomy

• The liver O6-methylguanine-DNA methyltransferase was reduced by hypophysectomy or thyroidectomy and could be increased by treatment with growth hormone or thyroxine [36].
• A decrease in cortisol secretion following hypophysectomy and subsequent cure by pituitary irradiation constitutes the evidence for pituitary origin in patient 2 [37].
• Castration also reduced flavin-containing monooxygenase-dependent activities, but not to the same extent as hypophysectomy [38].
• The objective was to determine the effect of hypophysectomy on the store of gonadotropin-releasing hormone (GnRH) in certain parts of the brain as revealed by immunocytochemistry [39].
• The LH requirements for ovulation in the pentobarbital-blocked proestrous CD rat have been studied by increasing serum gonadotropin levels through electrical stimulation of the brain and subsequently comparing the effects of timed hypophysectomy on ovulation and serum LH concentrations [40].

References