Our laboratory has made the initial observations suggesting that endogenous neuropeptide systems are related to neuro-oncogenicity and that perturbations of opiate receptor/endorphin interactions alter abnormal tissue growth. Recently, investigators have identified opiate receptors in developing brain and body tissues, endorphin immunoreactivity in the developing nervous system, and endorphins in the plasma and brain tissue of neonates. Questions as to the functional significance of endogenous opioid systems in early life have been raised. Our laboratory has now provided the first evidence that opiate receptors and endorphins are related to the regulation of normal body and brain development, and that their interaction in growth processes is extremely sensitive to perturbation. For example, continuous blockade of the opiate receptor by naltrexone, a potent and """"""""pure"""""""" opiate antagonist, during preweaning stages of rat neuro-ontogeny results in dramatic increases in brain size and cellular content. The present grant proposal is designed to elucidate the importance of opiate receptors and endogenous opioids in regulating neurobiological development and to ascertain the mechanisms responsible for these growth-related actions. Our strategy is to investigate the impact of continuous and intermittent opiate receptor blockade on neurogenesis and gliogenesis. Particular attention will be paid to the somatosensory cortex, hippocampus, and cerebellum during both the preweaning and postweaning periods, and histological, histochemical, morphometric, and biochemical techniques will serve in our assessment. The cellular mechanisms by which endogenous opioid systems regulate brain development will also be investigated. Cell proliferation, migration, and differentiation, as well as cell death, will be explored with light and electron microscopy and autoradiography. Since endorphins are suspected of participating in development, Beta-endorphin levels in plasma and brain tissue will be monitored. Finally, we will determine which opiate receptor subtypes are associated with mechanisms of growth. The number, affinity, subtypes, and anatomical location of opiate receptors during brain morphogenesis will be explored. Opiate receptor assays, in vitro autoradiography of receptor binding, and selective opiate antagonists will serve in our appraisal. This research is part of a long range program in cellular and molecular neurobiology which seeks to understand the fundamental principles underlying normal and abnormal brain development.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS020500-03
Application #
3400858
Study Section
Neurology A Study Section (NEUA)
Project Start
1984-09-01
Project End
1987-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Pennsylvania State University
Department
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Zagon, I S; Wu, Y; McLaughlin, P J (1999) Opioid growth factor and organ development in rat and human embryos. Brain Res 839:313-22
Zagon, I S; Verderame, M F; Allen, S S et al. (1999) Cloning, sequencing, expression and function of a cDNA encoding a receptor for the opioid growth factor, [Met(5)]enkephalin. Brain Res 849:147-54
Wilson, R P; McLaughlin, P J; Lang, C M et al. (1998) Temporal variation in cellular proliferation during recornification of mouse tail skin. Cell Prolif 31:191-201
Zagon, I S; Tobias, S W; Hytrek, S D et al. (1998) Opioid receptor blockade throughout prenatal life confers long-term insensitivity to morphine and alters mu opioid receptors. Pharmacol Biochem Behav 59:201-7
Zagon, I S; Hurst, W J; McLaughlin, P J (1998) Naltrexone is not detected in preweaning rats following transplacental exposure: implications for growth modulation. Life Sci 62:221-8
Levin, R J; Wu, Y; McLaughlin, P J et al. (1997) Expression of the opioid growth factor, [Met5]-enkephalin, and the zeta opioid receptor in head and neck squamous cell carcinoma. Laryngoscope 107:335-9
Zagon, I S; Hurst, W J; McLaughlin, P J (1997) Identification of [Met5]-enkephalin in developing, adult, and renewing tissues by reversed-phase high performance liquid chromatography and radioimmunoassay. Life Sci 61:363-70
Zagon, I S; Wu, Y; McLaughlin, P J (1997) Opioid growth factor is present in human and mouse gastrointestinal tract and inhibits DNA synthesis. Am J Physiol 272:R1094-104
Zagon, I S; Tobias, S W; McLaughlin, P J (1997) Endogenous opioids and prenatal determinants of neuroplasticity. Adv Exp Med Biol 429:289-303
McLaughlin, P J; Tobias, S W; Lang, C M et al. (1997) Opioid receptor blockade during prenatal life modifies postnatal behavioral development. Pharmacol Biochem Behav 58:1075-82

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