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Thyroid Hormone Stimulates g-Glutamyl Transpeptidase in the Developing Rat Cerebra and in Astroglial Cultures

IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata

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Title Thyroid Hormone Stimulates g-Glutamyl Transpeptidase in the Developing Rat Cerebra and in Astroglial Cultures
 
Creator Dasgupta, Asmita
Das, Sumantra
Sarkar, Pranab K
 
Subject Cell Biology & Physiology
 
Description Hypothyroidism in the developing rat brain is associated with enhanced oxidative stress, one of the earliest manifestations of which is a decline in the level of glutathione (GSH). To investigate the role of thyroid hormone (TH) on GSH homeostasis, the effect of TH on gglutamyl transpeptidase (gGT), the key enzyme involved in the catalysis of GSH, was studied. Hypothyroidism declined the specific activity of cerebral gGT at all postnatal ages examined (postnatal day 1–20) with a maximum inhibition of 42% at postnatal day 10. Intraperitoneal injection of TH to 15-day-old rat pups increased the specific activity of gGT by 25-30% within 4–6 hr. Treatment of primary cultures of astrocytes by TH also enhanced the specific activity of gGT by 30–40% within 4–6 hr. The induction of gGT by TH was blocked by actinomycin D or cycloheximide. gGT is an ectoenzyme that is normally involved in the catabolism of GSH released by astrocytes. In the presence of the gGTinhibitor, acivicin, GSH released in the culture medium of astrocytes increased linearly for at least 6 hr and TH had no effect on this accumulation pattern. In the absence of acivicin, GSH content of the medium from TH-treated cells was significantly lower than that of untreated controls due to activation of gGT by TH and a faster processing of GSH. Because the products of gGT reaction are putative precursors for neuronal GSH, the activation of gGT by TH may be conducive to GSH synthesis in neurons and their protection from oxidative stress. VVC 2005 Wiley-Liss, Inc.
 
Publisher John Wiley & Sons
 
Date 2005
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://www.eprints.iicb.res.in/326/1/JOURNAL_OF_NEUROSCIENCE_RESEARCH_82(_6)_851%2D857;2005[1].pdf
Dasgupta, Asmita and Das, Sumantra and Sarkar, Pranab K (2005) Thyroid Hormone Stimulates g-Glutamyl Transpeptidase in the Developing Rat Cerebra and in Astroglial Cultures. Journal of Neuroscience Research, 82. pp. 851-857. ISSN 0360-4012
 
Relation http://dx.doi.org/10.1002/jnr.20657
http://www.eprints.iicb.res.in/326/