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PubMed1991

Effects of stress and hypophysectomy on distribution of [3H]leucine in the mouse adrenal medulla.

Effect of stress and hypophysectomy on the distribution of [3H]leucine in the adrenal medulla of mice was examined by autoradiography. [3H]Leucine-derived radioactivity in adrenaline-storing (A) cells of the medulla was remarkably increased by immobilization with water immersion stress. The increase was prevented by adrenal denervation. Adrenal denervation itself reduced [3H]leucine incorporation by A cells. Hypophysectomy also reduced the amount of [3H]leucine in A cells. Although changes in noradrenaline-storing (NA) cells were not statistically significant, they were in the same direction as the changes observed in A cells. Present results showed that neural activity exerts trophic influence on leucine incorporation by adrenal chromaffin cells. Basal pituitary adrenocortical activity seems to be necessary for leucine incorporation in chromaffin cells.

Adrenal Glands↗
PubMed1996

Effects of stress and hypophysectomy on the uptake of [3H]2-deoxy-D-glucose in the mouse adrenal medulla: an autoradiographic study.

Effects of immobilization stress and hypophysectomy on the uptake of [3H] 2-deoxy-D-glucose (2DG) in the adrenal medulla of the mouse was examined by autoradiography. Radioactivity due to [3H]2DG in both adrenaline-storing and noradrenaline-storing cells was markedly increased by acute immobilization stress. Under immobilization stress, adrenaline-storing cells incorporated more 2DG than noradrenaline-storing cells. Adrenal denervation did not change the uptake of 2DG either in control or in stressed adrenal medulla. The uptake of [3H]2DG was also increased by hypophysectomy. Since withdrawal of cortical steroid hormones enhanced the uptake of 2DG and the adrenal denervation did not change the uptake, it is suggested that certain substances, such as bradykinin or histamine, which are released on immobilization stress from certain tissues other than sympathetic nerve endings in the medulla, enhanced the uptake of [3H]2DG. This phenomenon occurs mainly in adrenaline-storing cells.

Adrenal Medulla↗
PubMedDate not supplied

Hypothalamic CRF-like immunoreactivity in the rat after hypophysectomy or adrenalectomy.

Hypothalamic CRF-like immunoreactivity was measured in normal, hypophysectomized or adrenalectomized adult male rats. As expected, adrenalectomy resulted in decreased levels in plasma corticosterone and increased plasma levels of ACTH; hypophysectomy resulted in decreased levels in both corticosterone and ACTH. The hypothalamic content of CRF-like immunoreactivity in animals two weeks post-hypophysectomy or adrenalectomy was approximately seven times greater than that found in intact animals. At one week, post-surgery, small but statistically significant decreases in content of CRF-like immunoreactivity were observed. The results at one week are consistent with removal of feedback effects of ACTH and corticosterone causing increased release of CRF and decreased content. The increase in CRF-like immunoreactivity two weeks post-surgery is probably not related to direct feedback effects on release but may be due to increased synthesis secondary to long term removal of feedback inhibition.

Adrenalectomy↗
PubMed1985

Effect of hypophysectomy on plasma electrolytes and adrenal mineralocorticoid secretion in the terrestrial chelonian Testudo hermanni.

Na, K, ACTH, corticosterone and aldosterone plasma levels were studied in Testudo hermanni after hypophysectomy and dexamethasone administration. Hypophysectomy as well as dexamethasone treatment caused a deep decrease in the plasma levels of electrolytes, corticosterone and aldosterone when compared to sham-operated or normal controls. ACTH plasma level was markedly lower in hypophysectomized or dexamethasone-treated tortoises when compared to the controls but never reached undetectable levels. Administration of ACTH significantly increased plasma electrolytes and hormone levels in hypophysectomized and dexamethasone-treated tortoises. The present data seem to indicate that the pituitary plays a significant role on electrolyte homeostasis and on the regulation of plasma mineralocorticoids level in terrestrial chelonians.

Adrenal Glands↗
PubMed1986

Effect of hypophysectomy on absorption of inorganic phosphate by the eel intestine.

Hypophysectomy of freshwater-adapted eels resulted in a marked reduction in net absorption of PO4(3-) in the non-stripped and non-everted intestine. Stanniectomy was without effect on net movements of water and electrolytes in this isolated eel preparation. Repeated injections of eel calcitonin into the eel, kept either in deionized water or 10 mM CaCl2, had no effect on net absorption of water and electrolytes, including Ca2+ and PO4(3-). In the stripped and everted intestine, the net PO4(3-) absorption was significantly greater in the fed eel than in the starved fish. Hypophysectomy of the fed eel resulted in a significant reduction, not only in PO4(3-) absorption, but also in absorption of water and other electrolytes. It is suggested that pituitary hormone is involved in the intestinal PO4(3-) absorption of the eel.

Anguilla↗
PubMed1993

Effect of hypophysectomy on insulin-like growth factor (IGF)-1 binding activity of serum in chickens.

1. Hypophysectomy elevated IGF-1 binding activity of serum concurrently with decreases in circulating concentrations of IGF-1 and growth hormone (GH). 2. When sera pooled from each experimental group were chromatographed on a Sephadex G-200 column, IGF-1 binding activity was mainly found in 150 and 30 kilodalton (kDa) proteins. 3. Most of the serum IGF-1 were distributed among 150 kDa protein fractions. 4. Hypophysectomy elevated IGF-1 binding activity of these proteins, especially that of 30 kDa protein. 5. The binding of [125I]IGF-1 to the 30 kDa protein was inhibited by unlabelled IGF-1 but not by insulin, and saturated with a small amount of the ligand compared to the 150 kDa protein. 6. The IGF-1 binding activity of 30 kDa protein was dependent on GH status of chickens.

Animals↗
PubMed1988

Effect of hypophysectomy on the hypothalamic corticotropin-releasing factor (CRF) neuronal system in the eel: immunocytochemical study.

Male and female eels were hypophysectomized by a buccal approach and examined either 2 and 7 weeks (males) or 4 and 5 months (females) later. Intact and sham-operated eels served as controls. Fish were killed by decapitation, and the brains fixed in sublimated Bouin-Hollande solution and embedded in paraffin wax. Frontal and sagittal sections were immunostained by the peroxidase-antiperoxidase method, using antisera against cortiotropin-releasing factor (CRF) or arginine vasotocin (AVT). Immunoreactive (ir)-CRF was detected in parvo- and magnocellular perikarya of the preoptic nucleus. Sham hypophysectomy did not affect ir-CRF in cell bodies and fibres. After hypophysectomy, mainly after 4 or 5 months, there was an apparent increase in the number of ir-CRF cells. The intensity of immunostaining in the cell bodies was variable but not significantly different from the controls, but the two ventral axonal tracts were much thicker and contained more immunoreactive material than in sham-operated eels, while ir-CRF accumulated close to the sectioned pituitary stalk. The existence of negative feedback by cortisol on the CRF neurons is discussed.

Animals↗
PubMed1987

Rat adrenal medulla: levels of chromogranins, enkephalins, dopamine beta-hydroxylase and of the amine transporter are changed by nervous activity and hypophysectomy.

The levels of several constituents of chromaffin granules were determined in rat adrenal medulla after treatment with insulin or reserpine and after hypophysectomy. Insulin treatment induced increased levels of enkephalins, dopamine beta-hydroxylase, the amine carrier and of chromogranin B whereas catecholamines, cytochrome b-561 and chromagranin A remained slightly below control levels. Administration of reserpine led to similar changes with the exception of the enkephalins which increased much less. After hypophysectomy, chromogranin A was reduced to low levels; dopamine beta-hydroxylase, the amine carrier and catecholamines showed an intermediate reduction, whereas the other components remained at control levels. We can conclude that nervous stimulation of the adrenal medulla (by insulin and reserpine) induces the synthesis of enkephalins, dopamine beta-hydroxylase, the amine carrier and chromogranin B whereas the level of chromogranin A apparently depends on corticosteroids. Thus, major components of the secretory content and the membranes of chromaffin granules are regulated separately, which allows the biogenesis of chromaffin granules with a significantly altered composition.

Adrenal Medulla↗
PubMed1985

Hypophysectomy disturbs the noradrenergic feeding system of the paraventricular nucleus.

Injection of norepinephrine (NE) into the hypothalamic paraventricular nucleus (PVN) of satiated rats is known to stimulate eating behavior. In addition, drinking behavior is potentiated just prior to the onset of eating, followed by a strong inhibition of water intake. To understand the relationship between these PVN noradrenergic phenomena and endocrine processes associated with the PVN, chronically hypophysectomized animals were tested for their behavioral responsiveness to PVN NE injection. Pituitary ablation was found to abolish the NE-elicited eating response and the NE drinking suppressive effect. However, hypophysectomy had no impact on the NE-elicited preprandial drinking response, nor did it affect drinking produced by carbachol, angiotensin, and histamine, or the feeding and drinking responses induced by insulin. These results demonstrate that hypophysectomy disturbs PVN noradrenergic mechanisms in a behaviorally and pharmacologically specific specific manner.

Animals↗
PubMedDate not supplied

Plasma and cerebrospinal fluid alpha-MSH levels in the rat after hypophysectomy and stimulation of pituitary alpha-MSH secretion.

Immunoreactive alpha-MSH was measured in cerebrospinal fluid (CSF) and plasma of rats. While treatment with haloperidol increased alpha-MSH levels in the plasma concentration of alpha-MSH in the CSF showed little change. Hypophysectomy also had little effect on the concentration of alpha-MSH in the CSF despite the fall in plasma alpha-MSH levels. This lack of correlation between alpha-MSH levels in the CSF and plasma suggests that the systemic circulation does not deliver alpha-MSH to the CSF. The apparently normal levels of alpha-MSH in the hypothalamus after hypophysectomy suggests that this tissue is able to synthesize alpha-MSH and it is possible that the hypothalamus is a source of the alpha-MSH in the CSF.

Animals↗
PubMed1988

Effects of hypophysectomy on the sleep of neonatally monosodium glutamate-treated rats.

Monosodium Glutamate (MSG), known to induce neuronal cell degeneration of the arcuate nucleus of the hypothalamus, was subcutaneously injected (4 mg/g body wt.) at postnatal days 1 to 5 or 1 to 10 in female rats. Hypophysectomy was performed at 45-60 days of age. Sleep parameters were continuously recorded for at least 7 days. Results indicated that hypophysectomized (HYPX) NaCl-treated rats showed an increase of Slow Wave Sleep (SWS) (+29.6%) and a decrease of Paradoxical Sleep (PS) (-36.7%) durations. In MSG-treated rats, hypophysectomy did not alter SWS durations but it increased PS durations as MSG dosing increased. It was concluded that arcuate nucleus neurons seemed to be not critically involved in sleep production mechanisms.

Aging↗
PubMed1985

Effect of hypophysectomy on intestinal phosphate absorption in rats.

Intestinal active and passive transport of phosphate (Pi) was studied in hypophysectomized (HX) and intact rats using the in situ intestinal loop technique. Hypophysectomy resulted in a significant reduction of total Pi absorption under active transport conditions. However, when transport data were expressed on the basis of mucosal mass, the reduction was not apparent. Under passive transport conditions, net Pi absorption was lower in the HX rats even after correction for the decrease of mucosal mass. Administration of bovine growth hormone (bGH) did not change the intestinal Pi absorption in the HX rats. These results indicate that a decrease in mucosal mass following hypophysectomy is one of the factors that causes a decrease of intestinal Pi absorption.

Animals↗
PubMed2006

Mandibular bone stiffening and increased bone calcium mass in rats permanently stunted by hypophysectomy.

OBJECTIVE: This investigation was designed to obtain information on the changes induced by hypophysectomy on biometric parameters, bone calcium mass, and material and architectural properties during ontogenesis of the rat mandible. DESIGN: Female Sprague-Dawley rats were hypophysectomised (HX) at 30 days of age. A "basal control group" (BC) was sacrificed on the same day surgery was performed. An "age-matched intact control group" (CON) was also included. HX and CON rats were sacrificed when aged 6 months. Body weight was monitored weekly. Mandibular growth was estimated directly on the right hemimandible by taking measurements between stable anatomical points. Its mechanical properties were determined using a three-point bending mechanical test. Load was applied transversely to the bone axis at a point immediately posterior to the posterior surface of the third molar. The left hemimandibles were ashed in a muffle furnace at 600 degrees C for 18h and the ash weight obtained. Calcium content in the ashes was determined by atomic absorption spectrophotometry. It was taken as the mandibular calcium mass. Histomorphometric studies were performed on decalcified hemimandibles: total interradicular bone, bone volume, and height of the periodontal ligament were measured. CONCLUSIONS: Morphometric studies indicated that hypophysectomy in juvenile rats induced mandibular growth cessation, which was limited to the posterior part of the bone. Thus, the mandible maintained its juvenile proportions and showed an important deformation relative to age. In spite of the reduced bone size, both the mandibular weight and the calcium bone mass increased more than two times in ontogenia. Histomorphometric studies revealed that the interradicular bone volume was markedly increased. These findings strongly suggest that the bone that forms the mandible of the hypophysectomised rat under the conditions of the present study showed a higher than normal density. As evidenced from biomechanical studies, these bone properties, plus the significant stiffening of bone material tissue, were presumably responsible for the unnecessary and marked increment in the "load capacity" suffered by the mandible of the hypophysectomised rat during ontogenesis.

Animals↗
PubMed1980

Increased fetal breathing activity after fetal hypophysectomy.

Continuous recordings of tracheal pressure were made from seven control fetal sheep and seven in which hypophysectomy was attempted. Hypophysectomy was partial or complete in five fetuses, and in two the forebrain and brain stem were destroyed accidentally. The incidence of rapid, irregular breathing movements decreased in the control fetuses before spontaneous parturition. No fetal breathing movements were recorded from the two fetuses in which the forebrain and brain stem were destroyed. The incidence of fetal breathing movements (38.1 +/- 0.9 minutes per hour) was significantly greater in the fetuses after electrocoagulation of the fetal pituitary than in the control fetuses (24.5 +/- 1.7 min/hour, p less than 0.001). This was due to an increase in the incidence of rapid, irregular breathing movements and to intermittent, prolonged periods (more than 3 hours duration) of fetal breathing movements. The longest period of continuous fetal breathing recorded was 52 hours. There were two alternating patterns of breathing in these prolonged periods of fetal breathing movements. In one pattern, the breathing movements were irregular in rate and depth and resembled the episodes of breathing movements which occurred in the control fetuses. The other pattern consisted of breathing movements which were regular in rate and depth but among which were interspersed a few single deeper breaths. This pattern is similar to that reported previously for the lamb during quiet sleep after birth.

Animals↗
PubMed1999

Hypophysectomy and/or peroxisome proliferators strongly influence the levels of phase II xenobiotic metabolizing enzymes in rat testis.

The objectives of the present work were to determine the influence of hypophysectomy and/or peroxisome proliferators (PP) on certain xenobiotic-metabolizing enzyme activities, i.e. glutathione transferases (GST), glutathione peroxidase (GPX), phenol sulphotransferases (pSULT), phenol UDP-glucuronosyl transferases (pUGT), catalase, NADP(H) quinone oxidoreductase (QR) and epoxide hydrolases (EH) in the rat testes. Adult male rats, hypophysectomized and their sham-operated controls, were treated for 10 days with clofibrate (0.5%), perfluorooctanoic acid (0.05%, PFOA), acetylsalicylic acid (1%, ASA) and di(2-ethylhexyl)phthalate (2%, DEHP) in their diet. The results show that, in addition to both body and testis weight, hypophysectomy caused dramatic changes in most of the xenobiotic-metabolizing enzyme activities, which have been measured here. The most pronounced effects were seen in cytosolic QR (2.2-fold increase), pUGT (95% reduction), pSULT (75% reduction), mitochondrial catalase (75% reduction), microsomal EH (70% reduction) and microsomal GST (55% reduction). Treatment with PP, i.e. perfluorooctanoic acid (PFOA), clofibrate, acetyl salicylic acid (ASA) and di(2-ethylhexyl)phthalate (DEHP) showed varied effects on the xenobiotic-metabolizing enzyme activities, the highest effects (10-60% reduction) were seen in sham-operated animals. These effects were not so pronounced or were not seen in hypophysectomized rats except for the case of PFOA treatment, which caused increases of enzyme activities. The highest increases were seen with microsomal GST (70%), GPX (75%) and cytosolic EH (75%). It is concluded from these experiments that the regulation of several xenobiotic-metabolizing enzymes in the rat testis is affected by the pituitary and/or pituitary hormones and that different peroxisome proliferators have variable effects on the levels of these xenobiotic-metabolizing enzymes. The general trend of reduction in enzyme activities implies that the testis is less protected under conditions that can perturb hormonal status.

Animals↗
PubMed2002

Conception and spontaneous delivery after total hypophysectomy.

OBJECTIVE: To report the first case of pregnancy and spontaneous delivery after total hypophysectomy. DESIGN: A case report. SETTING: University hospital. PATIENT(S): A 34-year-old woman with panhypopituitarism after hypophysectomy in childhood for craniopharyngioma. INTERVENTION(S): Successful fertility treatment followed by sufficient hormone substitution therapy during pregnancy. MAIN OUTCOME MEASURE(S): Clinical variables. RESULT(S): The patient had an uncomplicated spontaneous delivery without any substitution of oxytocin before, during, or after delivery. CONCLUSION(S): Normal pregnancy and delivery are possible in women with lack of pituitary function. Maternal pituitary oxytocin release seems to play a limited role in the onset and progression of labor.

Adult↗
PubMed1998

Regulation of rat adrenal neuropeptide Y (NPY) content: effects of ACTH, dexamethasone and hypophysectomy.

While the presence of neuropeptide Y (NPY) in the adrenal cortex is well established, little is known about its regulation. In the present study the involvement of the pituitary gland in the regulation of rat adrenal NPY content was investigated. Rats were subjected to one of the following treatments: hypophysectomy, sham operation, ACTH, the synthetic glucocorticoid, dexamethasone, dexamethasone plus ACTH, or saline control. The immunoreactive NPY (irNPY) content of both capsule/zona glomerulosa and inner zone/medulla fractions were estimated by radioimmunoassay. Treatment with ACTH caused a significant decrease in both the capsular/zona glomerulosa and the inner zone/medulla irNPY content compared with controls, while hypophysectomy resulted in a significant increase in adrenal irNPY. Dexamethasone treatment caused a significant increase in capsular irNPY, which was reversed by simultaneous administration of ACTH. In the medulla, however, dexamethasone treatment significantly decreased irNPY content. These results suggest that there is differential regulation of adrenal irNPY content, with irNPY in the zona glomerulosa regulated directly by ACTH, while the irNPY content of the inner zones/medulla is regulated by glucocorticoids.

Adrenal Glands↗
PubMed1997

Effects of 17 beta-estradiol administration on cortical and cancellous bone of ovariectomized rats with and without hypophysectomy.

Pituitary hormones are essential for bone growth and bone turnover. Hypophysectomy (HX) diminishes mitogenesis and abolishes the high bone turnover rate induced by ovariectomy (OV). It is not known whether the suppressive effect of estrogen on bone resorption is diminished or abolished by HX. The present study investigates the effects of 17 beta-estradiol (E2) (20 micrograms/wk) on cortical and cancellous bone mass and bone turnover as measured by histomorphometry in HX + OV (HO) rats. Sprague-Dawley rats at 2 months of age were OV or HO and the experiment was performed over a 6 week period. Hypophysectomy + OV (HO) resulted in a cessation of periosteal bone formation, and longitudinal bone growth and a decrease in cancellous bone volume. The tibial dry weight and tibial density were significantly lower in the HO than in the intact or OV groups. Administration of E2 to HO rats partially prevented cancellous bone loss, whereas the same dosage of E2 fully prevented cancellous bone loss in rats with OV alone. Nevertheless, cancellous bone volume was higher in the HO + E2 than in the HO-alone groups. Estradiol administration in HO rats did not suppress cancellous bone formation rate or the eroded surface as much as it did in the OV rats. The suppressive effect of E2 on periosteal bone formation rate and mineral apposition rate was also diminished in HO rats. However, factorial ANOVA showed that the effects of E2 on increasing cancellous bone volume and decreasing periosteal bone formation rate and mineral apposition rate were still significant in the HO rats. Tibial dry weight and tibial density did not differ between HO and HO + E2 groups. In conclusion, we have demonstrated that the estrogen-induced effects of preventing cancellous bone loss, of suppressing bone formation, and resorption as seen in OV rats was diminished but not abolished in HO rats.

Animals↗