Epinephrine: a short- and long-term regulator of stress and development of illness : a potential new role for epinephrine in stress.

Epinephrine (Epi), which initiates short-term responses to cope with stress, is, in part, stress-regulated via genetic control of its biosynthetic enzyme, phenylethanolamine N-methyltransferase (PNMT). In rats, immobilization (IMMO) stress activates the PNMT gene in the adrenal medulla via Egr-1 and Sp1 induction. Yet, elevated Epi induced by acute and chronic stress is associated with stress induced, chronic illnesses of cardiovascular, immune, cancerous, and behavioral etiologies.

Stress and adrenergic function: HIF1α, a potential regulatory switch.

Stress elicits adrenal epinephrine and cortisol release into the bloodstream to initiate physiological and behavioral responses to counter and overcome stress, the classic "fight or flight" response (Cannon and De La Paz, Am J Physiol 28:64-70, 1911). Stress and the stress hormone epinephrine also contribute to the pathophysiology of illness, e.g.

PACAP-regulated phenylethanolamine N-methyltransferase gene expression.

Pituitary adenylate cyclase activating polypeptide (PACAP) induces the proximal -893 bp of rat phenylethanolamine N-methyltransferase (PNMT) gene promoter in PC12 cells via PACAP type I receptors. Deletion mutation analysis suggested that the initial -392 bp of promoter, containing early growth response protein (Egr-1), specificity protein 1 (Sp1) and activator protein 2 (AP-2) binding sites (-165, -168 and -103 bp, respectively), was sufficient for PACAP activation. Egr-1 and AP-2 involvement was supported by PACAP induction of their mRNA and protein.

Hypoxia and adrenergic function: molecular mechanisms related to Egr-1 and Sp1 activation.

Hypoxia is shown to regulate the stress hormone epinephrine through its biosynthesis by phenylethanolamine N-methyltransferase (PNMT) via PNMT gene activation and transcription factors Egr-1 and Sp1 in adrenal medulla-derived PC12 cells. Moderate hypoxia (5% oxygen) markedly stimulates PNMT promoter-driven luciferase activity in the cells. Hypoxia increases Egr-1 and Sp1 mRNA and nuclear protein content and Egr-1 and Sp1 protein-DNA binding complex formation.

Hypoxic stress-induced changes in adrenergic function: role of HIF1 alpha.

Sustaining epinephrine-elicited behavioral and physiological responses during stress requires replenishment of epinephrine stores. Egr-1 and Sp1 contribute by stimulating the gene encoding the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT), as shown for immobilization stress in rats in adrenal medulla and for hypoxic stress in adrenal medulla-derived PC12 cells. Hypoxia (5% O(2)) also activates hypoxia inducible factor (HIF) 1alpha, increasing mRNA, nuclear protein and nuclear protein/hypoxia response element binding complex formation.

Adrenergic responses to stress: transcriptional and post-transcriptional changes.

Stress effects on adrenergic responses in rats were examined in adrenal medulla, the primary source of circulating epinephrine (Epi). Irrespective of duration, immobilization (IMMO) increased adrenal corticosterone to the same extent. In contrast, Epi changed little, suggesting that Epi synthesis replenishes adrenal pools and sustains circulating levels for the heightened alertness and physiological changes required of the "flight or fight" response.

Promoter analysis of human glutamate carboxypeptidase II.

The expression of glutamate carboxypeptidase II (GCP II) is reduced in selective brain regions in schizophrenic patients. To investigate transcriptional mechanisms regulating the human GCP II gene, a 3460 bp DNA fragment comprised of the proximal 3228 bp of 5' untranscribed sequence and first 232 bp of 5' UTR portion of this gene was cloned into the mammalian luciferase reporter gene vector pGL3-Basic. Transfection assays in human astrocyte-derived SVG and human prostate tumor-derived LNCaP cells demonstrated that constructs with 3460, 1590 and 761 bp portions of 5' region of human GCP II gene were able to drive the luciferase reporter gene.

Stress-induced changes in epinephrine expression in the adrenal medulla in vivo.

Immobilization (IMMO) stress was used to examine how stress alters the stress hormone epinephrine (EPI) in the adrenal medulla in vivo. In rats subjected to IMMO for 30 or 120 min, adrenal corticosterone increased to the same extent. In contrast, EPI changed very little, suggesting that EPI synthesis replenishes adrenal pools and sustains circulating levels for the heightened alertness and physiological responses of the 'flight or fight' response.

Transcriptional regulation of phenylethanolamine N-methyltransferase in pheochromocytomas from patients with von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2.

Pheochromocytomas in multiple endocrine neoplasia type 2 (MEN-2) express phenylethanolamine N-methyltransferase (PNMT), the enzyme that catalyzes conversion of norepinephrine to epinephrine, whereas those in von Hippel-Lindau (VHL) syndrome do not. Consequently, pheochromocytomas in MEN-2 produce epinephrine, whereas those in VHL syndrome produce mainly norepinephrine. This study examined whether transcription factors known to regulate expression of PNMT explain the different tumor phenotypes in these syndromes.

Nerve growth factor regulates adrenergic expression.

The mechanism by which nerve growth factor (NGF) regulates adrenergic expression was examined in PC-12 cells transfected with a rat phenylethanolamine N-methyl-transferase (PNMT) promoter-luciferase reporter gene construct pGL3RP893. NGF treatment increased PNMT promoter-driven luciferase activity in a dose- and time-dependent manner. Induction was attenuated by inhibition of the extracellular signal-regulated kinase mitogen-activated protein kinase (MAPK) pathway ( approximately 60%) but not by inhibition of the protein kinase A (PKA), protein kinase C, phosphoinositol kinase, or p38 MAPK pathways.

Epinephrine biosynthesis: hormonal and neural control during stress.

1. Stress contributes to the pathophysiology of many diseases, including psychiatric disorders, immune dysfunction, nicotine addiction and cardiovascular illness. Epinephrine and the glucocorticoids, cortisol and corticosterone, are major stress hormones.

Genetic mechanisms for adrenergic control during stress.

Cortisol and epinephrine released in response to stress are replenished via activation of the hypothalamic-pituitary-adrenal (HPA or stress) axis. Immobilization (IMMO) stress in rats stimulates epinephrine production in part via the gene encoding the epinephrine-synthesizing enzyme phenylethanolamine N-methyltransferase (PNMT). PNMT mRNA rose up to 7.

Regulation of the rat phenylethanolamine N-methyltransferase gene by transcription factors Sp1 and MAZ.

The rat phenylethanolamine N-methyltransferase (PNMT) gene promoter contains 1-base pair (bp) overlapping consensus sequences for Sp1 and MAZ transcription factors at -48 and -38 bp, respectively. Gel mobility assays using PC-12-derived RS1 cell nuclear extracts or in vitro translated proteins showed that Sp1 and MAZ specifically bind to these elements, that MAZ displaces/prevents Sp1 binding, and that Sp1 and MAZ binding is mutually exclusive, with occupancy dependent on each factor's concentration and affinity for its consensus element. In transfection assays, PNMT promoter activation by Sp1 and MAZ depends on promoter length, with -893 bp of sequence yielding greatest activation.

Why is the adrenal adrenergic?

The adrenal gland is the body's primary source for epinephrine production and release, and the chromaffin cells that comprise the adrenal medulla possess all of the catecholamine biosynthetic machinery, including phenylethanolamine N-methyltransferase (PNMT), the enzyme synthesizing epinephrine from norepinephrine. In most species, epinephrine, also known as adrenaline, is the predominant neurotransmitter/neurohormone expressed by chromaffin cells. Present knowledge about "what makes the adrenal adrenergic" is derived from studies of normal and neoplastic adrenal medullary tissue and cells, with the PNMT gene serving as a marker of adrenergic function.

Protein kinase A and protein kinase C signaling pathway interaction in phenylethanolamine N-methyltransferase gene regulation.

The protein kinase A (PKA) and protein kinase C (PKC) signaling pathways appear to interact in regulating phenylethanolamine N-methyltransferase (PNMT) promoter-driven gene transcription in PC12 cells. Forskolin treatment of cells transfected with the rat PNMT promoter-luciferase reporter gene construct pGL3RP893 increased promoter activity approximately two-fold whereas phorbol-12-myristate-13 acetate (PMA) treatment had no effect. However, simultaneous forskolin and PMA treatment synergistically activated the PNMT promoter approximately four-fold, suggesting that PKC stimulation requires prior induction of the PKA pathway.

Mesotelencephalic dopamine neurochemical responses to glucocorticoid administration and adrenalectomy in Fischer 344 and Lewis rats.

The effects of alterations in peripheral corticosterone levels on multiple dopamine neurochemical estimates were examined in inbred Fischer and Lewis inbred rat strains. 2x2 ANOVA's (treatment x strain) showed a main effect for treatment (1 week CORT versus placebo) on the concentrations of the dopamine metabolites homovanillic acid and dihydroxyphenylacetic acid in the medial prefrontal cortex, with lower levels after treatment, but no significant treatment versus strain interaction. There was no effect of CORT treatment on DA metabolites in the nucleus accumbens shell or dorsal striatum.

Cholinergic and peptidergic regulation of phenylethanolamine N-methyltransferase gene expression.

The splanchnic nerve, innervating the adrenal medulla, releases a variety of neurotransmitters that stimulate genes involved in catecholamine biosynthesis. In particular, cholinergic agonists have been shown to induce phenylethanolamine N-methyltransferase (PNMT) gene expression through activation of both nicotinic and muscarinic receptors in vivo and in vitro. By contrast, the role of peptidergic neurotransmitters in adrenal medullary PNMT gene expression remains unclear.

Glucocorticoid responsiveness of the rat phenylethanolamine N-methyltransferase gene.

Two newly identified, overlapping (1 bp) glucocorticoid response elements (GREs) at -759 and -773 bp in the promoter of the rat phenylethanolamine N-methyltransferase (PNMT; EC 2.1.1.