鱼类嗅觉器官的构造与功能

鱼类的嗅觉器官是其重要的化学感受器之一,由鼻孔、鼻腔和位于鼻腔内的嗅囊构成,鱼类嗅觉器官的进化与发展也经历了一个由低级到高级、由简单到复杂的过程。鱼类的嗅觉器官在鱼类的生活中,诸如摄食、御敌、生殖和集群等行为上发挥着重要的作用。     

Structure and Function of the Vertebrate Pineal Gland

This review presents data from the literature on structure and function of the pineal gland. Discussed are the histological and ultrastructural characteristics of the gland, its function according to novel results, peculiarity of synthesis and secretion of melatonin and its function, as well as the role of the pineal gland in circadian organization of organisms. The problems of evolution of the pineal function in the row of vertebrates are considered.     

m-Synephrine: Normal Occurrence in Adrenal Gland

Abstract: Gas chromatography-mass spectrometry-selected ion monitoring has been used to identify m-synephrine (phenylephrine) in bovine adrenal gland. After ion exchange chromatography, m-synephrine was converted to its N-trifluoroacetyl-O-trifluoroacetoxy derivative and identified by retention time and relative intensities of the two characteristic ions at m/e 140 and m/e 455. Deuterated m-synephrine was synthesized and used as an internal standard for quantitative analysis. Bovine adrenal gland contains 83 ng g-¹ (range, 33-131) of endogenous m-synephrine.     

Mixed Corticomedullary Carcinoma of the Adrenal Gland: A Case Report

ObjectiveTo report the case of a 78-year-old woman with mixed corticomedullary carcinoma of the adrenal gland, and to review other reported lesions that exhibit clinical and/or histopathologic features of both adrenal cortical and medullary differentiation.MethodsWe describe the patient’s clinical findings and laboratory test results, as well as the gross and histopathologic features of her tumor. We also review the literature pertaining to mixed corticomedullary adenomas and cortical tumors with clinical features of pheochromocytoma, and vice versa.ResultsA 78-year-old woman with a 10-cm left adrenal mass was hospitalized for management of hypertensiveurgency. Laboratory workup revealed elevated urinary metanephrine excretion and elevated serum dehydroepiandrosterone sulfate levels. She underwent left adrenalectomy. Pathologic examination of the lesion showed mixed cortical and medullary histologic characteristics, as well as gross and microscopic evidence of malignancy. Including the present case, we identified 17 cases of neoplasms that exhibit features of mixed corticomedullary differentiation.ConclusionsThis report represents the first documented case of mixed corticomedullary carcinoma. Several benign lesions combine clinical, biochemical, and/or histopathologic evidence of both adrenal cortical and medullary differentiation, including mixed corticomedullary adenomas and corticotropin-secreting pheochromocytomas. The differential diagnosis of a lesion with mixed cortical and medullary features should also include a malignant neoplasm. (Endocr Pract. 2012;18:e37-e42)     

Adrenal Function in Hypothyroidism

In ten patients with hypothyroidism the adrenal response to stimulation with tetracosactrin was found to be normal, and to be unchanged after they had been treated with thyroxine. Though the response to insulin hypoglycaemia was less in the hypothyroid phase, it was never outside the normal limits. Hence it seems unlikely that the adrenal response to stress is appreciably lowered in hypothyroidism.     

Differential Expression of SNAP-25 Isoforms and SNAP-23 in the Adrenal Gland

Abstract : In the rat adrenal gland, we previously observed that SNAP-25 is not restricted to the plasmalemma in noradrenergic cells as it is in adrenergic cells, and hypothesized that SNAP-25 isoform expression is different in the two phenotypes. Expression of SNAP-25 isoforms and SNAP-23 was examined by immunoblotting, immunofluorescence, and RT-PCR. Amplifications of SNAP-25 mRNAs were combined with Southern hybridization, restriction enzyme analysis, and sequencing of cloned PCR products to compare SNAP-25 isoform expression in rat and bovine adrenal glands. SNAP-25 and SNAP-23 mRNA and protein are expressed in the glands ; SNAP-23 is enriched in the adrenal cortex, whereas SNAP-25 is restricted to the adrenal medulla. Furthermore, high levels of SNAP-25 and low levels of SNAP-23 are observed in the PC12 cells, whereas both SNAP-25 and SNAP-23 are expressed in adrenal medullary cultures. In all extracts, the SNAP-23 mRNA corresponded to SNAP-23a. SNAP-25a is the major form expressed in rat adrenal glands (75%), as it is in PC12 cells (80%), but both SNAP-25a and SNAP-25b (40% vs. 60%) are expressed in bovine adrenal medulla in situ and in culture. In addition, an enriched population of adrenergic cells (93%) expressed a higher level of SNAP-25b (70%), suggesting that this isoform may not be restricted to fast neurotransmission.     

Activation of Tyrosine Hydroxylase by Nicotine in Rat Adrenal Gland

The administration of nicotine activates tyrosine hydroxylase in the rat adrenal gland. This activation is apparently maximal 25 min after a single subcutaneous injection of nicotine at 2.3 mg/kg. Repeated injections of nicotine (seven injections once every 30 min) are associated with a persistent activation of adrenal tyrosine hydroxylase for at least 3 h. The nicotinic receptor antagonist hexamethonium does not significantly inhibit the nicotine-mediated activation of tyrosine hydroxylase in innervated adrenal glands. However, hexamethonium completely blocks the activation of adrenal tyrosine hydroxylase by nicotine in denervated adrenal glands. Furthermore, even though a single injection of nicotine activates tyrosine hydroxylase in both innervated and denervated adrenal glands, repeated injections of nicotine do not activate tyrosine hydroxylase in denervated adrenal glands. Our results suggest that the systemic administration of nicotine activates adrenal tyrosine hydroxylase by two mechanisms: (1) via direct interaction with adrenal chromaffin cell nicotinic receptors; and (2) via stimulation of the CNS leading to the release from the splanchnic nerve of substances that interact with adrenal chromaffin cell receptors other than the nicotinic receptor.     

Localization of Type-2 Angiotensin II Receptor in Adrenal Gland

The localization of the type-2 angiotensin II receptor (AT2) in the adrenal glands of rats, guinea pigs, bovines, and humans was examined at the mRNA and protein levels. PCR products for AT2 were detected in the adrenal cortices and adrenal medullae of all the mammals examined with an RT-PCR technique. Three different anti-AT2 antibodies (Abs), whose specificity was confirmed in our hands, recognized a 50-kDa protein in the adrenal glands of the four mammals, and this recognition was abolished by the preabsorption of an Ab with an antigen. Immunoblotting and immunohistochemistry revealed that the 50-kDa protein was expressed consistently and variably in the adrenal cortices and medullae of various mammals, respectively. We conclude that the 50-kDa AT2 is consistently expressed in the adrenal cortex in a wide variety of mammals. (J Histochem Cytochem 58:585–593, 2010)     

The Evolution of Thyroidal Function in Fishes

Although the thyroid gland evolved from the gut, there is noevidence that thyroxine functions as part of the gastro-intestinalendocrine system nor does it have any major function analogousto the control of glucose by the pancreatic islets. The controlof the thyroid evolved from the pituitary control of the gonadsuggesting that an early role of thyroxine was in reproduction.This idea is supported by the presence of cycles of thyroidactivity associated with reproduction in both elasmobranchsand teleosts. In teleosts thyroxine is necessary for gonadalmaturation. The numerous other effects of thyroxine in teleostsmay have evolved from this maturational effect or have beenadded to it during the course of teleost evolution.     

Effect of Oxotremorine on Ornithine Decarboxylase Activity of the Adrenal Gland in Rat

Abstract: In this work we have studied the mechanism for the increase of adrenal ODC (ornithine decarboxylase, EC 4.1.1.17) activity provoked by oxotremorine, a muscarinic agonist. 1. Oxotremorine increased medullary ODC activity maximally at 2 h. Cortical enzyme responded much more slowly. 2. Blockade of peripheral muscarinic receptors with methylatropine partially reduced the response to oxotremorine in the medulla, but not cortex. 3. Hy-pophysectomy abolished the cortical, but not the medullary, responses to oxotremorine. Methylatropine reduced the effect of oxotremorine on medullary ODC in hypophysectomized rats. 4. In unilaterally splanchnicotomized rats oxotremorine caused an increase of ODC activity of the denervated adrenal gland relative to control value; activities in both medulla and cortex were significantly lower than those observed in the innervated gland. Evidence was obtained for a compensatory increase of ODC activity of the adrenal cortex (but not medulla) on the intact side of unilaterally operated rats. 5. Surgical intervention, in the form of a sham operation for transection of the spinal cord, leads to an increase of ODC activity in both parts of the adrenal gland. Transection of the cord attenuates these increases. 6. The additional increase of medullary ODC activity owing to the administration of oxotremorine to sham-operated rats is partially reduced in the adrenal medulla by muscarinic blockade, and completely in the cortex. This effect of methylatropine in regard to cortical ODC activity was not apparent in the other experiments with intact or unilaterally splanchnicotomized (unoperated side) rats. The results with unilaterally splanchnicotomized rats and those with transected spinal cord suggest that oxotremorine-induced modifications of adrenal ODC activity are centrally mediated, above the level of origin of the splanchnic nerves in the spinal cord (T_8–10). Experiments with hypophysectomized rats show that the response of the adrenal cortex to oxotremorine is entirely mediated by the hypophysis.