Muscarinic M1, M3, Nicotinic,GABAA and GABAB Receptor ...

signals (Zawalich & Rasmussen, 1990). While the preeminent nutrient fuel that
regulates secretion is glucose, it is also clear that the vagally derived signal
acetylcholine plays an important role (Shiota et al., 2002). The underlying
explanation for impaired insulin secretion in diabetes resides, in the inability of
glucose to activate information flow in the phospholipase C/protein kinase C
(PLC/PKC) signal transduction system to the same quantitative extent in mouse
islets as it does in rat and, presumably, human islets as well. Our study showed a
decreased expression of phospholipase C expression in the pancreatic islets of
hypoglycemia and diabetic rats which shows that hypoglycemia and the
subsequent glucose deprivation adversely affects the pancreatic second messenger
enzyme regulation. The impact of acetylcholine on the β cell is initiated by the
interaction of the neurotransmitter with the muscarinic cholinergic receptor, the
activation of phospholipase C and the subsequent generation of inositol
phosphates and diacylglycerol (Berridge, 1987; Gilon &. Henquin, 2001). The
decreased phospholipase C expression is associated with impaired cholinergic and
GABAergic eceptor signaling during hypoglycemia and hyperglycemia.
Cholinergic stimulation of the β cell activates the insulin secretory
process, a response that is mediated by PLC (Kelley et al., 1995). The nature of
the receptor type that couples the activation of PLC to release has yet to be
precisely determined and both the muscarinic M1 and M3 receptor types appear to
be expressed in the β cell (Lismaa et al., 2000). Our study on PLC expression
shows that glucose deprivation is detrimental to innate insulin secreting function
and other functions associated with pancreas. Thus, hypoglycemia exacerbates the
dysfunction caused by diabetes.
CREB PROTEIN EXPRESSION IN BRAIN OF EXPERIMENTAL RATS
The cAMP responsive element binding protein (CREB) is a nuclear
protein that modulates the transcription of genes with cAMP responsive elements
in their promoters. CREB is a basally expressed, post-translationally activated
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