VIP enhances TRH-stimulated prolactin secretion of pituitary tumours. Studies with 31P NMR |
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| Authors: | R A Prysor-Jones J J Silverlight J S Jenkins A N Stevens J L Rodrigues J R Griffiths |
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| Institution: | 1. Département de Biologie Moléculaire, Institut Pasteur, 25, Rue du Dr. Roux, 75724 Paris, France;2. Laboratoire de Neuropathologie, CHU Côte de Nacre, 14040 Caen, France |
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| Abstract: | Intravenous thyrotrophin releasing hormone (TRH) caused a 6.5-fold increase in plasma prolactin (PRL) in rats carrying implanted pituitary tumours. Vasoactive intestinal polypeptide (VIP) had no effect, but TRH given after VIP raised TRH stimulated secretion 13-fold above basal. 31P NMR spectroscopy showed that VIP caused a decrease in high energy metabolites (depleted phosphocreatine, elevated inorganic phosphate and lowered intracellular pH). TRH alone caused a similar but smaller effect; given after VIP, it caused no detectable depletion. We suggest that the changes in high energy metabolite concentrations reflect increased cellular energy consumption consistent with a priming process (stage 1) in PRL secretion, followed by hormone release (stage 2). VIP induces stage 1 whereas RTH induced both stages. |
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| Keywords: | Immunocytochemistry Native myosin isozyme Methylthiouracil Soleus Gastrocnemius |
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