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Results for “PITUITARY HORMONES”

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PubMed1987

Pituitary hormones and aging.

This article reviews the reported effects of aging on pituitary structure and function in man.

Adrenocorticotropic Hormone↗
PubMed1987

Immunoglobulins of Lambert-Eaton myasthenic syndrome inhibit rat pituitary hormone release.

We speculated that IgG from patients with Lambert-Eaton myasthenic syndrome (LES) would inhibit calcium-dependent hormone secretion in rat anterior pituitary (AP) cells. Primary cultures of normal AP cells were continuously exposed to crude IgG from an LES patient or from healthy control subjects, and the incubation media were assayed for prolactin (PRL) or growth hormone (GH). The LES IgG caused a time- and concentration-dependent reduction of PRL and GH release compared with control IgG over 0.5 to 48 hours using concentrations of 0.01 to 4.0 mg/ml. The calcium-channel activator maitotoxin stimulated 45Ca2+ uptake and PRL release from AP cells under control conditions, and the LES IgG significantly reduced both actions of maitotoxin. Thus LES IgG appears to modulate an AP antigenic site, perhaps representing an integral component of voltage-gated calcium channels that may share properties with similar presynaptic elements at the neuromuscular junction.

Animals↗
PubMed1993

[Initial characterization of a new miniature animal model in the rat: studies on anatomy, pituitary hormones and GH mRNA in miniature rat Ishikawa].

Miniature rat Ishikawa (MRI) is an experimental model for pituitary miniaturism with an autosomal recessive mode of inheritance. This paper reports the discovery and initial characterization of a new mutant rat. The mutation arose spontaneously in a breeding colony of Wistar rats at the Ishikawa Animal Laboratory (Saitama). Body growth in MRI was retarded in 56% and 71% of normal control rats for males and females, respectively. In immunohistochemical studies for anterior pituitary sections, GH secreting cells were reduced in the amounts and the intensity of stain in MRI compared with normal control rats. There was no detectable difference in the amounts or distribution of LH, FSH, PRL, TSH and ACTH between MRI and normal control rats. MRI showed a selective reduction in pituitary GH contents and in response to human GRH. Pituitary GH contents were approximately 31% of normal in males and 45% in females. Pituitary TSH contents and serum TSH levels were within the normal range in MRI. Total T3 and T4 levels were also within the normal range in MRI. Pituitary total mRNA extracts revealed that GH message in male MRI was reduced in 53% of normal control rats, and that fragment size of GH mRNA was within the normal range. The immunohistochemical findings, supported by a reduced GH content in pituitary extracts and low GH response to GRH, were compatible with a deficiency of GH caused by a reduced expression of pituitary GH mRNA. MRI, which showed a selective pituitary GH deficiency, may provide a useful new model for studying the endocrinological aspects of the growth.

Animals↗
PubMed2003

Changes in diurnal sympathoadrenal balance and pituitary hormone secretion in subjects with Leu7Pro polymorphism in the prepro-neuropeptide Y.

Neuropeptide Y (NPY) is an important neurotransmitter in the central and peripheral nervous systems. It has a regulatory role in cardiovascular and metabolic functions and control of hormone release. The leucine 7 to proline 7 (Leu7Pro) polymorphism in the signal peptide of prepro-NPY is associated with increased blood lipid levels, accelerated atherosclerosis, and diabetic retinopathy. This study elucidated the role of this polymorphism in diurnal cardiovascular, metabolic, and hormonal functions of healthy subjects during rest. The two study groups comprised individuals with different genotype, but they were matched for age and body mass index. Subjects with the Leu7Pro polymorphism had significantly lower plasma NPY and norepinephrine concentrations, lower insulin concentrations, higher glucose concentrations, and lower insulin-glucose ratio in plasma than the controls. Heart rate was significantly higher during daytime in the subjects with Leu7Pro polymorphism. Furthermore, these subjects had significantly lower prolactin concentrations in plasma. Systolic and diastolic blood pressure, serum free fatty acid and plasma leptin, ACTH, cortisol, LH, FSH, TSH, free thyroxin, and melatonin concentrations were similar during the 24-h period, compared with controls. These results show that genetically determined changes in NPY levels lead to widespread consequences in the control of sympathoadrenal, metabolic, and hormonal balance in healthy subjects.

Adult↗
PubMed2001

Food restriction differentially affects pituitary hormone mRNAs throughout the adult life span of male F344 rats.

Because neuroendocrine mechanisms may contribute to the antiaging effects of food restriction (FR), we measured the effect of FR on mRNAs encoding anterior pituitary (AP) tropic hormones. Slot blots or RNase protection assays were done on AP RNA from 3-, 6-, 12-, 18- and 24-mo-old male F344 rats consuming food ad libitum (AL) or food restricted (FR; to 60% of AL food intake) from 6 wk. Both AL and FR rats gained body weight during the study (P < 0.05), but FR rats weighed approximately 40% less (P < 0.0001). Messenger RNA levels were expressed in two ways, i.e., per total AP and per microgram total AP RNA. Proopiomelanocortin (POMC) mRNA/microg RNA was higher (P < 0.0005) in FR than in AL rats at all ages. Thyroid-stimulating hormone (TSH) beta mRNA declined with age (P < 0.05) in AL but not FR rats and was reduced by FR up to 12 mo (P < 0.01). Growth hormone (GH) mRNA/microg RNA declined with age (P < 0.05) in AL but not FR rats, and total GH mRNA in the AP was reduced by FR at early ages (P < 0.05). FR reduced prolactin (PRL) mRNA and its age-related increase (P < 0.0005). Levels of luteinizing hormone (LH) beta and follicle-stimulating hormone (FSH) beta mRNAs did not differ between AL and FR rats until 12 mo, but thereafter rose in FR (LH beta mRNA; P < 0.01, FSH beta mRNA; P < 0.05). Many of these changes in gene expression corroborate previously reported hormonal changes in FR rodents and mutant mice with extended life spans, and thus provide further support for the hypothesis that an altered hormonal milieu contributes to the antiaging effects of food restriction.

Aging↗
PubMed1975

Pituitary hormones and growth retardation in rats raised at simulated high altitude (3800m).

Growth and the endocrine status of the pituitary and thyroid glands were studied in rats born and raised in a hypobaric chamber at a simulated high altitude of 3800 m (SHA); comparisons were drawn with similar rats at sea level. From birth until 40 days of age, SHA rats weighed significantly less than controls with the most striking growth impairment found in female SHA rats. Relative organ weights of anterior pituitary glands, ovaries and uteri from 40-day-old female SHA rats were significantly less than controls. Pituitary content of growth hormone (GH) was reduced in 40-day-old female SHA rats while the content of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were significantly increased over sea level controls. Plasma levels of GH, LH, FSH and thyrotropin (TSH) and pituitary TSH levels did not differ from control values. However, thyroidal uptake of 131I and plasma protein-bound 131I were significantly reduced in SHA rats as compared with controls. It is suggested that (1) the continuous exposure of developing female rats to hypoxia significantly impairs pituitary function and reproductive maturation, and (2) that despite other environmental factors acting on the developing organism at high altitude, growth retardation in rats born and raised at high altitudes is primarily a consequence of hypoxia.

Altitude↗