Abstract
Catecholamine (CA) secretion from the adrenal medullary tissue is a key step of the adaptive response triggered by an organism to cope with stress. Whereas molecular and cellular secretory processes have been extensively studied at the single chromaffin cell level, data available for the whole gland level are much scarcer. We tackled this issue in rat by developing an easy to implement experimental strategy combining the adrenal acute slice supernatant collection with a high-performance liquid chromatography-based epinephrine and norepinephrine (NE) assay. This technique affords a convenient method for measuring basal and stimulated CA release from single acute slices, allowing thus to individually address the secretory function of the left and right glands. Our data point that the two glands are equally competent to secrete epinephrine and NE, exhibiting an equivalent epinephrine:NE ratio, both at rest and in response to a cholinergic stimulation. Nicotine is, however, more efficient than acetylcholine to evoke NE release. A pharmacological challenge with hexamethonium, an α3-containing nicotinic acetylcholine receptor antagonist, disclosed that epinephrine- and NE-secreting chromaffin cells distinctly expressed α3 nicotinic receptors, with a dominant contribution in NE cells. As such, beyond the novelty of CA assays from acute slice supernatants, our study contributes at refining the secretory behavior of the rat adrenal medullary tissue, and opens new perspectives for monitoring the release of other hormones and transmitters, especially those involved in the stress response.
Highlights
Catecholamines (CA) play important physiological roles in human and animal organisms by contributing to maintain body homeostasis
high-performance liquid chromatography (HPLC) Coupled with Fluorescence Detection: A Reliable Approach to Assay CA Secretion from Single Adrenal Slice Supernatant
A challenging issue of the study was to settle an experimental procedure allowing a reliable quantitative measurement of CA secreted by the medullary tissue from acute adrenal slices
Summary
Catecholamines (CA) play important physiological roles in human and animal organisms by contributing to maintain body homeostasis. E and NE are among the first hormones to be released in response to CA Assay in Adrenal Slice Supernatants stressful situations, and once delivered into the blood circulation, they exert multiple peripheral actions, in particular on the cardiovascular system, leading to appropriate adjustments of blood pressure and cardiac rhythm, and on the energy metabolism, helping the organism to cope with stress [1]. The stimulussecretion coupling underlying adrenal CA release relies on both an incoming synaptic command arising from the splanchnic nerve terminals [2] and a local gap junctional communication between chromaffin cells [3,4,5,6,7]. The secretory behavior of the adrenal glands is usually examined through the determination of CA (and/or their metabolites) levels in the systemic blood circulation or in the urines. Measurements of plasma and urinary CA and/or their metabolite levels can be used to for the diagnosis and the follow-up of several neuroendocrine tumors, such as neuroblastoma [8], paragangliomas [9], pheochromocytomas [10,11,12], early arterial hypertension [13, 14], and for evaluating hemodynamic and sympathoadrenal functions in patients in intensive cares [15,16,17]
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