An increasing body of evidence indicates that macromolecules derived from target organs are essential for the survival of embryonic sympathetic neurons (SN) in culture. Whether these factors also influence the development of noradrenergic characteristics (i.e., uptake, storage, synthesis and release of norepinephrine (NE) is virtually unknown. An attractive possibility exists that survival and development of SN and their functional maturation may be controlled by discrete influences. The Principal Investigator (PI) has successfully attempted to measure one of the important functions of SN maintained in culture. It is possible to evoke Ca-dependent release of 3H-NE by electrical stimulation of SN maintained in culture. The potential advantages of the method are: 1) Release can be studied from essentially a pure population of SN; 2) SN can be obtained from embryos of different ages, allowing to study noradrenergic function in relation to development; 3) SN can be maintained in culture for long periods in the absence of non-neuronal cells and serum; 4) SN can be co-cultured with muscle cells, other types of neuronal and non-neuronal cells to study interactions between cells and their effect on noradrenergic properties. In preliminary experiments PI has studied release properties of embyronic SN, and they appear to be dramatically different from those of mature mammalian SN. A more intriguing observation is that cultured SN differed in their release properties even from their equivalents growing in the embryonic heart. For example, release evoked from cultured SN was not blocked by tetrodotoxin (TTX) or facilitated by tetraethylammonium (TEA). The release was not even under the control of presynaptic adrenergic modulation. In sharp contrast, release evoked from SN innvervating the embryonic heart was blocked and potentiated by TTX and TEA, respectively, and modulated by exogenous NE. Ca was essential for the release in both situations. The immediate objective is to establish noradrenergic characteristics of embryonic SN growing in culture and in the heart. The long-term objective is to establish whether the target organ plays a role in the development of noradrenergic characteristics of their neurons during synaptogenesis by examining noradrenergic properties in SN cultured under different conditions, particularly in the presence of heart cells. It is hoped that the proposed experiments will reveal that survival and development of SN and maturation of their functional properties are controlled by different signals.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
7R01HL018601-11
Application #
3335633
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1988-09-01
Project End
1989-08-31
Budget Start
1988-09-01
Budget End
1989-08-31
Support Year
11
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Wayne State University
Department
Type
Schools of Medicine
DUNS #
City
Detroit
State
MI
Country
United States
Zip Code
48202
Wakade, A R; Przywara, D A; Bhave, S V et al. (1995) Cardiac cells control transmitter release and calcium homeostasis in sympathetic neurons cultured from embryonic chick. J Physiol 488 ( Pt 3):587-600
Lopez, M G; Shukla, R; Garcia, A G et al. (1992) A dihydropyridine-resistant component in the rat adrenal secretory response to splanchnic nerve stimulation. J Neurochem 58:2139-44
Malhotra, R K; Wakade, T D; Wakade, A R (1988) Comparison of secretion of catecholamines from the rat adrenal medulla during continuous exposure to nicotine, muscarine or excess K. Neuroscience 26:313-20
Malhotra, R K; Bhave, S V; Wakade, T D et al. (1988) Protein kinase C of sympathetic neuronal membrane is activated by phorbol ester--correlation between transmitter release, 45Ca2+ uptake, and the enzyme activity. J Neurochem 51:967-74
Wakade, A R; Wakade, T D; Malhotra, R K et al. (1988) Excess K+ and phorbol ester activate protein kinase C and support the survival of chick sympathetic neurons in culture. J Neurochem 51:975-83
Malhotra, R K; Wakade, T D; Wakade, A R (1988) Vasoactive intestinal polypeptide and muscarine mobilize intracellular Ca2+ through breakdown of phosphoinositides to induce catecholamine secretion. Role of IP3 in exocytosis. J Biol Chem 263:2123-6
Malhotra, R K; Wakade, A R (1987) Vasoactive intestinal polypeptide stimulates the secretion of catecholamines from the rat adrenal gland. J Physiol 388:285-94
Malhotra, R K; Wakade, A R (1987) Non-cholinergic component of rat splanchnic nerves predominates at low neuronal activity and is eliminated by naloxone. J Physiol 383:639-52
Harish, O E; Kao, L S; Raffaniello, R et al. (1987) Calcium dependence of muscarinic receptor-mediated catecholamine secretion from the perfused rat adrenal medulla. J Neurochem 48:1730-5
Wakade, A R; Malhotra, R K; Wakade, T D (1986) Phorbol ester facilitates 45Ca accumulation and catecholamine secretion by nicotine and excess K+ but not by muscarine in rat adrenal medulla. Nature 321:698-700

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