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PubMed1983

Studies on seminiferous tubule fluid production in the adult rat: effect of hypophysectomy and treatment with FSH, LH and testosterone.

Seminiferous tubule fluid production in adult rats was studied using the technique of unilateral efferent duct ligation (EDL), the production rate representing the difference in testis weight over the time since ligation. Following EDL, fluid production increases linearly for 6 h and linearly at a slightly slower rate for a further 18 h with a sharp decrease thereafter. No differences in fluid production were noted for rats aged between 90-310 days. Forty-eight hours after hypophysectomy there was a significant fall (26%) in fluid production prior to any significant decrease in testis weight. Fluid production continued to decline with time after hypophysectomy eventually reaching a plateau 16-44 days later at levels approximately 15% of those found in control rats. Treatment of rats hypophysectomized 4 days earlier with ovine FSH for 3 days did not restore fluid production, but treatment with ovine LH, testosterone propionate (TP) or FSH together with TP for a similar duration all restored fluid production to normal. On the other hand, treatment of intact adult rats with ovine LH significantly increased fluid production but the effect of treatment with testosterone alone did not reach significance. The results indicate that in the adult rat, seminiferous tubule fluid production is controlled principally by testosterone secreted by the Leydig cell in response to LH stimulation.

Animals↗
PubMed1981

Effect of hypophysectomy and adrenalectomy on 5-hydroxytryptamine uptake by rat hypothalamic synaptosomes and blood platelets.

The effect of adrenalectomy and hypophysectomy on 5-HT uptake by rat platelets and hypothalamic synaptosomes taken from the same animal was studies. The experiments were performed 1-2 weeks after the operations of the shamoperations. After adrenalectomy a significant decrease of 25% in 5-HT uptake by platelets was noted. In synaptosomes there was a similar trend, but the decrease was not significant. After hypophysectomy a significant 25% decrease in 5-HT uptake was observed both in platelets and in synaptosomes. These results suggest that corticosteroid hormones might mediate adaptive changes of 5-HT uptake both in synaptosomes and in blood platelets. Blood platelets have been used as a peripheral model of serotoninergic nerve terminal in studies concerning physiology of monoamines systems. But the present results suggest that also in some pathological conditions changes in platelet biochemistry could reflect those in the CNS neurones.

Adrenalectomy↗
PubMed1984

Galactorrhoea following hypophysectomy in a boy with a prolactinoma.

An 18-year-old boy with delayed puberty was found to have a large prolactinoma. Hypophysectomy led to a fall in serum prolactin concentration, although it remained markedly elevated. The introduction of replacement therapy, including testosterone, resulted in painful swelling of the breasts and galactorrhoea. Bromocriptine therapy resulted in a cessation of galactorrhoea and normalization of serum prolactin concentrations. The absence of galactorrhoea in association with an astronomical concentration of prolactin, and its onset in association with diminished prolactin concentrations following hypophysectomy and the introduction of testosterone therapy, indicate that galactorrhoea requires the presence of high prolactin concentrations to act on mature breast tissue. This would account for the rarity of galactorrhoea in prepubertal children with prolactinomas.

Adenoma, Chromophobe↗
PubMed1978

Analysis of spermidine and spermine in rat liver. Effect of hypophysectomy on polyamine concentrations.

A simple, rapid, reproducible assay for tissue polyamines using a standard unmodified amino-acid analyzer is described. This technique will allow accurate measurement of the polyamines from as little as 10 mg of liver in less than 1 h. We have used this method to establish the optimum conditions for the extraction of polyamines from liver and to study the effects of hypophysectomy on polyamine content of rat liver. Hypophysectomy caused a fall in RNA, protein, putresine, and spermidine content prevented the normal increase in spermine in rat liver seen with increasing age.

Aging↗
PubMed1978

Protein turnover in rat skeletal muscle: effects of hypophysectomy and growth hormone.

The role of growth hormone in regulating protein turnover was examined in a perfused preparation of rat skeletal muscle. The perfused muscle maintained in vivo levels of ATP and creatine phosphate and exhibited constant rates of oxygen consumption and protein synthesis. Hypophysectomy reduced the rate of protein synthesis, the concentration of RNA, and the efficiency of protein synthesis in gastrocnemius muscle to 30, 46, and 66 percent of normal, respectively. In vivo treatment of hypophysectomized (hypox) rats with bovine growth hormone (250 microgram/day for 5 days) resulted in small increases in protein synthesis and RNA, whereas synthesis/RNA was returned to near normal. Elevation of ribosomal subunits in psoas muscle indicated an inhibition of peptide-chain initiation in hypox rats that was reversed by in vivo growth hormone treatment. Thus, hypox rats exhibited both a decreased capacity and a decreased efficiency of protein synthesis. Growth hormone replacement primarily increased efficiency of protein synthesis. The rate of protein degradation and the activity of cathepsin D in gastrocnemius muscle were decreased by hypophysectomy. Growth hormone treatment had no significant effect on degradation.

Animals↗
PubMed1981

Effects of hypophysectomy and thyroidectomy on leucine metabolism in adipose tissue.

Hypophysectomy doubled the rate of oxidation of L-[1-14C]leucine to 14CO2 by segments of rat epididymal adipose tissue. Thyroidectomy, but not adrenalectomy, produced identical results. Acceleration of leucine oxidation occurred even in the presence of glucose and saturating concentrations of insulin and leucine, suggesting that thyroidectomy increased the capacity to degrade leucine. Treatment of thyroidectomized rats with triiodothyronine (T3) decreased leucine oxidation, but at least 4 days were required. Treatment of hypophysectomized rats with T3 for 6 days was ineffective unless growth hormone was also given. A similar acceleration was also seen in the rate of oxidation of alpha-keto[1-14C]isocaproate, the deaminated analogue of leucine, but neither hypophysectomy nor thyroidectomy accelerated the rate of oxidation of isovalerate, the next metabolite in the degradative sequence. These observations suggested that hypothyroidism, whether primary or secondary, might increase the activity of the mitochondrial reaction responsible for the decarboxylation of alpha-ketoisocaproate. Because thyroidectomy failed to modify the rate of oxidation of [1-14C]pyruvate that occurs by an analogue reaction and requires the same cofactors, an effect of thyroidectomy on cofactor availability was ruled out. Direct assay in a cell-free homogenate revealed a nearly twofold increase in the activity of the alpha-ketoisocaproate dehydrogenase enzyme complex. The findings support the conclusion that hypothyroidism increases the amount or activity of the mitochondrial enzyme complex responsible for decarboxylation of branched-chain alpha-keto acids.

Adipose Tissue↗
PubMed1993

Effect of hypophysectomy on plasma catecholamines and enkephalins in fetal sheep.

The aim of this study was to determine the effect of fetal hypophysectomy on the plasma concentrations of catecholamines and enkephalins in the fetal sheep between 120 and 140 days gestation under basal and hypoxic conditions. During basal conditions, there was no difference in the plasma concentrations of norepinephrine and epinephrine between intact and hypophysectomized groups. Fetal plasma norepinephrine concentrations were significantly increased during hypoxia in intact fetal sheep (7.2 +/- 2.2 pmol/ml, -15 min; 20.2 +/- 7.7 pmol/ml, 30 min) between 130 and 140 days, but after fetal hypophysectomy there was no significant norepinephrine response to hypoxia at this gestational age (4.7 +/- 1.3 pmol/ml, -15 min; 8.8 +/- 2.8 pmol/ml, 30 min). In contrast, fetal plasma epinephrine concentrations were significantly increased during hypoxia in both the intact (1.5 +/- 0.5 pmol/ml, -15 min; 3.3 +/- 1.7 pmol/ml, 30 min) and hypophysectomized groups (1.8 +/- 0.6 pmol/ml, -15 min; 6.8 +/- 4.1 pmol/ml, 30 min) between 130 and 140 days. During basal conditions, plasma concentrations of free Met-Enk were significantly less in hypophysectomized fetal sheep (170.8 +/- 34.3 pg/ml; 120-140 days) than in intact fetal sheep (305.6 +/- 47.3 pg/ml). There were no differences, however, in the fetal plasma concentrations of total Met-Enk between the intact (18.0 +/- 1.9 ng/ml) and hypophysectomized (16.9 +/- 2.6 ng/ml) groups. During hypoxia, there were no changes in the fetal plasma concentrations of either free or total Met-Enk in the intact or hypophysectomized groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1976

Hypophysectomy and regulation of body weight in the genetically obese Zucker rat.

Genetically obese Zucker "fatty" rats (fa/fa) and nonobese siblings were weighed regularly from 7 to 150 days of age to determine the onset and time course of the excessive weight gain that characterized the fatty rat. At 150 days of age, male and female fatties and their lean littermates were sham operated or hypophysectomized to examine the role of the pituitary in the fatty obesity. The operated animals were then weighed until sacrifice at 220 days of age, when adrenal weights, gonadal weights, uterine weights, and the Lee Index were determined. Fatty rats were significantly heavier than their nonobese littermates even in the 2nd wk of life (day 7-13). Complete hypophysectomy blocked the continued development of the fatty obesity but did not eliminate the adiposity established prior to hypophysectomy. It is concluded that the pituitary and the major endocrine pathways it controls are not the locus of the primary genetic lesion responsible for maintaining the Zucker fatty rat obesity.

Animals↗
PubMed1985

Hypothalamic obesity after hypophysectomy or adrenalectomy: dependence on corticosterone.

Recent studies have found that the hyperphagia and obesity resulting from lesions of the ventromedial hypothalamus (VMH) are both reversed and prevented by complete adrenalectomy. Several previous experiments, however, reported little or no suppression of VMH weight gain in hypophysectomized (HYPOX) rats. This study directly compared the effects of hypophysectomy and adrenalectomy on hypothalamic obesity in adult female rats. Complete adrenalectomy (i.e, stress-induced plasma corticosterone less than 1.0 micrograms/dl) totally suppressed abnormal weight gain in the first 20 days after VMH lesions but did not affect intracranial self-stimulation. Hypophysectomy also resulted in suppression of weight gain, but the HYPOX-VMH rats nevertheless gained significantly more weight than HYPOX rats with sham lesions. However, the HYPOX-VMH animals had very low levels of plasma corticosterone and adrenocorticotropin (ACTH) (from residual pituitary tissue or of diencephalic origin), and incompletely adrenalectomized rats with similar low levels of plasma corticosterone gained an equal amount of weight after VMH lesions. It was concluded that adrenal glucocorticoid hormones play a largely permissive role in the VMH syndrome, with only very small levels required for the manifestation of obesity.

Adrenalectomy↗
PubMed1978

Physical activity and hypophysectomy on the aerobic capacity of ligaments and tendons.

Traditionally, ligaments and tendons (L and T) have been regarded as metabolically inert structures. However, sufficient biochemical evidence on the metabolism of collagen has indicated that such a concept is no longer tenable. To determine whether L and T respond to increased or decreased levels of chronic exercise, studies were undertaken to measure their aerobic capacities. For comparative purposes, similar measurements were obtained from liver and skeletal muscles secured from normal and hypophysectomized male rats. Oxygen consumption and cytochrome oxidase (CO) activity was recorded from cell suspensions that had been prepared with the inclusion of collagenase and with elastase added to the medium. The O2 results showed that L and T had values that were approximately 10 times lower than liver tissue and 7.5 times less than the means from skeletal muscles. Hypophysectomy caused marked reductions in O2 uptake of liver and muscle tissues; but had no impact on L and T. When CO activity of these connective tissues were evaluated, immobilization and hypophysectomy caused significant reductions that ranged from -36% to -59% respectively. Training, on the other hand, resulted in increases of less than 10% in the activity of this enzyme within L and T while being elevated in muscle tissue by 58%. It was concluded that the metabolic activity of L and T was lowered with decreased levels of physical activity but it was unclear why chronic exercise did not produce the opposite effect.

Animals↗
PubMed1988

Distribution of immunoreactive prolactin in the male and female rat brain: effects of hypophysectomy and intraventricular administration of colchicine.

Immunohistochemical studies have identified immunoreactive prolactin (IR-PRL) in the hypothalamus and other areas of the rat brain. However, immunocytochemical techniques make it difficult to quantify the amount of antigen localized in a specific region. In this study, IR-PRL was extracted from selected regions of the rat brain, consisting of the median eminence, dorsal and ventral hypothalamus, thalamus, amygdalae, cerebellum, cortex, hippocampus, septum, pons-medulla, and olfactory lobes, and the concentrations of IR-PRL were determined by radioimmunoassay. Whereas IR-PRL was detected in all brain regions in both the male and the female rat brain, the concentrations of IR-PRL in the female rat were significantly greater than those measured in the corresponding region of the male rat brain. In the female rat, hypophysectomy significantly reduced, but did not eliminate, the concentration of IR-PRL in hypothalamus, amygdala, thalamus, and pons-medulla. In contrast, hypophysectomy did not affect the concentration of IR-PRL in any brain regions of the male rat. Injection of colchicine into the lateral ventricle decreased the concentration of IR-PRL in the median eminence and increased the concentration of IR-PRL in the ventral hypothalamus in male and female rats. In addition, extracted hypothalamic and pituitary IR-PRL displayed similar dilution curves in the PRL assay and elution patterns on Sephadex G-100. These data indicate that both the male and the female rat brain contains an IR-PRL-like material with physicochemical properties similar to those of pituitary PRL. This material is differentially distributed in the male and female brain and is found in greater concentrations in the female brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effect of hypophysectomy and growth hormone administration on hypothalamic growth hormone-releasing hormone and somatostatin content: relationship to age-related growth rate.

The purpose of these studies was to evaluate the effect of age-related differences in growth rate on the hypothalamic content of growth hormone-releasing factor (GHRH) and somatostatin (SS) and on the short loop feedback regulation of GHRH and SS. Percent weight gain, GHRH content, and SS content in control adolescent (8 weeks) and adult rats (6 months) were compared in normal rats administered supraphysiologic amounts of rat growth hormone (rGH) or in hypophysectomized rats receiving thyroxine and corticosterone with or without physiologic rGH replacement. In control adolescent rats, the rate of weight gain was 5-fold higher than in adult rats. GHRH content was higher in adolescent rats, while SS content was lower. After the administration of supraphysiologic amounts of rGH, GHRH content increased in adolescent rats but did not change in adult rats. SS content was unchanged in either age group. Following hypophysectomy GHRH content declined similarly in both groups, whereas the decrease in SS content was greater in adolescent rats. With replacement rGH, weight gain was restored, GHRH content increased but not fully to control, and SS content did not change. The ratio of SS content to GHRH content (SS/GHRH) was higher in control adult rats than in adolescent rats. SS/GHRH increased following hypophysectomy and returned to control values by rGH replacement. We conclude that age-related differences in growth rate are accompanied by appropriate changes in SS/GHRH and that SS and GHRH are regulated by short loop feedback at both ages with increased responses in adolescent rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Hormonal regulation of rat hypothalamic neuropeptide mRNAs: effect of hypophysectomy and hormone replacement on growth-hormone-releasing factor, somatostatin and the insulin-like growth factors.

Hormonal feedback regulation of hypothalamic peptides putatively involved in growth hormone (GH) regulation has been studied by measurement of steady-state mRNA levels in male hypophysectomized rats with or without thyroid hormone, corticosterone, testosterone or GH replacement. Hypothalamic GH-releasing factor (GRF) mRNA levels increased progressively following hypophysectomy to 420% of sham levels after 15 days while hypothalamic insulin-like growth factor I (IGF-I) and insulin-like growth factor II (IGF-II) mRNA levels decreased to less than 40% of sham levels. Whole hypothalamic somatostatin mRNA levels were not significantly different from sham. One week of continuous GH infusion restored hypothalamic IGF-I mRNA to levels (95%) indistinguishable from those in sham-operated controls but had no effect on either IGF-II or GRF mRNA. Thyroid hormone, corticosterone and testosterone treatment without GH had no effect on the hypophysectomy-induced reduction of either IGF-I or IGF-II mRNA levels but reversed the elevation of GRF mRNA. We conclude that hypothalamic IGF-I may be involved in GH feedback regulation and thus may function as a hypothalamic modulator of GH. In contrast, IGF-II may be regulated by one of the pituitary trophic hormones but not by GH or the target hormones tested. Finally, hypothalamic GRF mRNA regulation appears to be complex and may include target hormone feedback.

Animals↗
PubMed1996

Appearance of beta-2-microglobulin in rat hypothalamic magnocellular neurons after hypophysectomy.

To clarify the relationship between neuronal cell degeneration and MHC class-I complex expression, we have immunohistochemically examined the distribution of beta(2)-microglobulin in the hypophysectomized rat hypothalamus. In the sham-operated control rats, positive stainings were distributed only in blood vessels in the hypothalamic areas where magnocellular neurons were localized. Three days after hypophysectomy, positive stainings appeared in a large number of magnocellular neurons in the paraventricular and supraoptic nuclei. Most of such beta(2)-microglobulin-positive cells were simultaneously stained with antivasopressin serum. The pattern of distribution of positive cells and the intensity of the stainings remained unchanged at least until the 14th day. These morphological findings suggest that the process of degeneration of hypothalamic magnocellular neurons after hypophysectomy is a useful model to investigate the role of MHC class I complex in the brain.

Animals↗
PubMed1977

Effect of corticotropin, steroidogenic inhibitors and hypophysectomy on the nuclear volumes of fasciculata cells in the rat adrenal cortex.

The purpose of this investigation was to measure quantitatively nuclear volumes in outer fasciculata cells in adrenal glands of rats subjected to chronic stimulation of steroidogenesis by ACTH, or to chronic inhibition of functional activity by hypophysectomy or by injection of the steroidogenic inhibitos, U-8113 (p-aminophenyl butanone) and SU-4885 (metopirone). Nuclear volumes, after a recovery period from those effects, were also measured. Chronic daily administrations of ACTH for 7, 14, and 30 days led to a progressive, statistically significant increase in nuclear volumes of fasciculata cells. These changes were found to have been reversed 14 days after discontinuation of hormone treatment. Hypophysectomy resulted in a significant decrease in nuclear volumes. The steroidogenic inhibitors SU-4885 and U-8113 had a biphasic effect on the nuclear volumes with an early decrease and subsequent increase to normal values. Since a decrease in nuclear volumes in the adrenal glands of inhibitor-treated subjects occurred in the presence of cellular hypertrophy and a significant increase in adrenal weights, it is concluded that changes in nuclear volumes can be positively correlated with the secretory activity of the cell rather than with the sizes of cells or glands.

Adrenal Cortex↗
PubMed1985

Comparative study of histological and kinetic variations of the digestive mucosa and pancreatic parenchyma after hypophysectomy in the rat. Light and electron microscopic study.

Variations of the pancreatic parenchyma, the gastric mucosa and the intestinal mucosa were studied in adult male Wistar rats on day 8 and 15 after hypophysectomy. All results were compared with those obtained in pair-fed control rats. Hypophysectomy affected small intestine as well as gastric mucosa. Hypotrophy was observed on day 8 as most of the morphological parameters reached the maximal decrease. By contrast, hypoplasy occurred on day 15, when the labeling index (LI) decreased significantly. In the intestine, however, a decrease of the LI was observed only for the upper proliferative cells of the crypts. In the gastric mucosa, the LI was reduced only in the proliferative zone containing progenitor cells (isthmic region). Consequently, the cell differentiation is not similarly affected on all levels of the digestive tract.

Animals↗
PubMed1980

Fine structural effects of hypophysectomy on the aging rat pineal gland.

A study was undertaken to examine the effects of pituitary removal on age-related changes in the female rat pineal. Three 9-month-old controls, three 23-month-old controls and three rats hypophysectomized at 19 months and sacrificed at 23 months of age were utilized. Electron microscopic evaluation indicated that following hypophysectomy there was a significant loss of lipid droplets, no change in the frequency of light and dark pinealocytes or cytoplasmic dense bodies (probably lipofuscin), a trend towards increased granular deposits between cells, no change in the number of pinealocytes with nuclear invaginations and decreased numbers of cells with nuclear inclusions. The results indicate that while some tissues (kidney) may show reduced aging indices following hypophysectomy other tissues such as the pineal may be detrimentally affected.

Aging↗
PubMed1993

Morphometric analysis of the muscle fibres of the soleus muscle of the ageing rat: long-term effect of hypophysectomy and food restriction.

This communication reports on the effects of ageing, hypophysectomy and food restriction on the fibre sizes of the soleus muscle which is primarily concerned with posture. The results reported here are compared with those previously shown for the gastrocnemius muscle which is involved mainly with locomotion. Muscle fibre size (measured as equivalent circle diameter) in the soleus muscle of the male Wistar rat increased from youth at 130 days (type 1 fibres, 61.2 microns; type 2, 58.3 microns) to middle age at 600 days (type 1 fibres, 70.4 microns; type 2, 68.0 microns) and then underwent atrophy in old age to 1,000 days (type 1 fibres, 54.5 microns; type 2, 38.0 microns). There was no growth or atrophy of these fibres in either hypophysectomized or food-restricted rats. There was an increased range of fibre sizes in control rats between youth and old age being 5-fold for type 1 fibres and 3-fold for type 2 fibres, but there was a loss of type 2 fibres in hypophysectomized rats. This ageing process in the range of fibre size was retarded by hypophysectomy (2-fold increase for type 1 fibres) and to a lesser extent by food restriction (3-fold increase for type 1 fibres). Muscle fibre atrophy and compensatory hypertrophy were not as prominent in the hypophysectomized and food-restricted groups as in the old control groups. In general these effects were similar to those previously shown for the gastrocnemius muscle. However, atrophy of both type 1 and type 2 fibres in old age was more pronounced in the soleus muscle. The retarded ageing of the soleus muscle in hypophysectomized and food-restricted rats was probably due to the absence or reduced circulating levels of hormones known to target muscle cells, such as growth hormone and thyroxine.

Aging↗