Localization of enkephalins in adrenaline cells and the nerves innervating adrenaline cells in rat adrenal medulla

Abstract

The coexistence of met5- and leu5-enkephalin-like immunoreactivities with catecholamines in the rat adrenal medulla was studied with combined fluorescence microscopy and immunocytochemistry. Both met5- and leu5-enkephalin-like immunoreactivities were localized in few heavily stained adrenaline cells and in a population of nerves innervating adrenaline cells and as well as ganglion cells among the adrenaline cells. Only occasionally single noradrenaline cells exhibited light immunostaining for both enkephalins but no positive fibers could be found around the noradrenaline cells. In electron microscope the immunoreaction was seen in the granules of the adrenaline cells and in the large synaptic vesicles of the nerve terminals around the adrenaline cells. The present findings suggest that enkephalin-like immunoreactivity coexists mainly with adrenaline in rat adrenal medulla and that the enkephalin immunoreactive terminals regulate secretion of adrenaline from rat adrenal medulla.

Induction of lnterleukin-1β mRNA and Enkephalin mRNA in the Rat Adrenal Gland by Lipopolysaccharides Studied by in situ Hybridization Histochemistry (Part 2 of 2)

“…Pyrogenic doses of LPS, including the dose used in the present study, appeared to involve macrophage-independent factors in the stimulation of the HPA axis [44]. It is also conceivable that IL-1 produced by adrenal chromaffin cells stimulates glucocorticoid release through a paracrine action, directly or through a local release of CRF/ACTH from the chro maffin cells [10-12, 45, 46], LPS administration also resulted in an induction of ENK mRNA in the adrenal gland in accordance with recent findings by Behar et al [47], A weak hybridization signal for ENK mRNA was seen in the adrenal chromaf fin cells of control animals, in agreement with earlier demonstrations of constitutive expression [18][19][20][21]. ENK mRNA signal occurred in more than 50% of the adrenal chromaffin cells in the LPS-treated animals, suggesting that at least the adrenergic cells were positive.…”

Fetal Adrenalectomy Does Not Affect Circulating Enkephalins in the Sheep Fetus during Late Gestation

“…Opioid peptides, including the methionine enkephalin (Met-Enk)-containing peptides, are co-localised with cat echolamines in the adrenal medulla and sympathetic neu rones in a number of species [1][2][3][4], It has been demon strated that Met-Enk-containing peptides are present in the adrenal medulla of the fetal sheep [5], we have also found that these peptides are present as early as 80 days of gestation [6][7], but whether these intra-adrenal opioids are released and have a physiological role in the unstressed fetus has not been clearly established.…”

Substance P Immunoreactivity in the Rat Adrenal Gland during Postnatal Development

“…Our previous study revealed that the cytoplasm of both NA cells and A cells contained SP [20]. Further, other studies have shown that Leu-ENK, Met-ENK, NPY and CGRP are also present in chromaffin cells [13,14,18,20,23,26]. These results might suggest that SP, other peptides, NA and/or A are synthesized in the chromaffin cells and released from the granules in response to adequate stimuli.…”

“…Other studies reported that the cholinergic neurons in the Nucleus intermediolateralis of the spinal cord (thoracic-lumber) contained SP or SP mRNA [30,32]. The presence of SP/ChAT-immunoreactive neurons has been demonstrated in the sphenopalatine, otic, internal carotid, and ciliary ganglia [2]; in the pedunculopontine and the laterodorsal tegmental nuclei of brainstem [27,28]; and in the small intestine [15,23]. These facts imply that SP-containing nerve fibers are originate from the Nucleus intermediolateralis of the spinal cord, dorsal root ganglia, and other ganglia or nucleus mentioned above.…”

“…It has been reported that the chromaffin cells and nerve fibers in the adrenal gland of various mammals contain a variety of peptides and enzymes such as Leuenkephalin (Leu-ENK) [2], Met-enkephalin (Met-ENK) [23,26], nitric oxide synthase (NOS) [3], neuropeptide tyrosine (NPY) [13,18], pituitary adenylate cyclase activating polypeptide (PACAP) [7], and vasoactive intestinal polypeptide (VIP) [10]. Furthermore, they contain SP [3,12,16] and calcitonin gene related peptide (CGRP) [14] as markers of sensory neurotransmitters, suggesting that these nerve fibers were recognized as a sensory innervation in the adrenal gland [4,34].…”