Behavioral Neuroscience, lecture on Acetylcholine
USD Department of Biology
Behavioral Neuroscience
Summers
Honey Bee Ecology and Behavior
Honey Bee Neuroanatomy
Fundamentals of Neurocircuitry
Sensory Afferent input for Proboscis Extension
Apis mellifera Gating Proboscis Extension
Learning to Drink
Conditioned Proboscis Extenstion
Motor Neuron output for Proboscis Extension
Acetylcholine ACh
Octopamine OA
Integration: Honey Bee Conditioned Drinking
Honey Bee figures
Honey Bee Conditioned Drinking Neurocircuitry
end     Acronyms/Abbreviations
Honey Bee Conditioned Drinking
VI. Acetylcholine (ACh) 
         	Acetylcholine
	A. substrates: choline and acetyl CoA
	                       (diet)       (Glycolysis and Kreb's)
		        
		1. synthetic enzyme: choline acetyltransferase (CAT)

			a. cytosolic   (most is synaptic)
			
				i. vesicular transporter = vAChT necessary
				
					(1) package ACh for synaptic release

			b. CoA left over

			
		2. degradative enzyme: acetylcholine esterase (AChE)

			a. membrane protein

			b. catabolites = choline and acetate

			c. turnover = 150ms	or	5,000 ACh molecules/s

			
	B. Muscarinic and Nicotinic Receptors 	(membrane proteins)

		1. muscarinic M1 - M5    7tm

			a. slow response time (100 - 250 ms)

			
			b. act directly on ion channels 	

				i. open or close K+, Ca++, or Cl- channels

					(1) may lead to depolarization 
					   or hyperpolarization

					   
			c. and activate 2nd messenger system (via G proteins)
			
				i. M1,3,5 Gp(q/11)PLCIP3/Ca++ & DG/PKC

				ii. M2,4 GiACcAMP  PKA  CREB  CRE


		2. Nicotinic

			a. four glycosylated peptide chains a, b, g, d in muscle
	
				i.  arranged with 2 a and 1 each b, g, d = 5 total
                			
			b. neuronal only a & b

				i.  arranged with 8 types of a + 3 types of b
                			
			c. ACh binds to the a subunit

				i. binding causes conformational change

					1) allows cations, not anions, to pass

						a) Na+ pases first, 
							depolarizing muscle cell membrane

					2) deporlarization  Ca++ release
						from ER stimulates muscular contraction
					    
						 
	C. Central ACh Distribution in vertebrates: Involved in Learning
	
		1. ACh is produced in the nucleus basalis 

			a. projections to the cerebral cortex and many parts of the brain

			b. these cells degenerate during Alzheimer's disease

			
		2. ACh is in 2 specific populations in the limbic system

			a. septum to hippocampus  & habenulo-endopeduncular projections

			b. short axon striatal cells
	
	D. Central Integrative distribution in Honey Bees: Involved in Learning

		1. LH neurons
        
		2. MB neurons
    
	E. Autonomic NS
	
		1. all sympathetic and parasympathetic preganglionic neurons

		2. parasympathetic postganglionic neurons
	
	
	F. ACh in Invertebrates: transmitter for Sensory neurons

		1. Honey Bee Antenna Olfactory Receptor neurons secrete ACh

			a. Antenna lobe glomerular neurons are also cholinergic

				i. project to LH and MB
            
			b. Crayfish mechanosensory neurons are cholinergic 

			c. sensory neurons in vertebrates use Glu

		2. sensory neurons in some other invertebrates (leeches) are glutamatergic

	G. ACh as a transmitter for motor actions and coordination
	
		1. motor neurons 
			\ all skeletal neuromuscular junctions
		
			a. Invertebrates
		
				i. Honey Bee: SEG motor neurons to proboscis muscles
                
				ii. crayfish: motor neurons to abdominal muscles
                
				iii. Leech L, VE, DE, AE, HE
			
				iv. Aplysia gill and siphon  retraction
			
			b. Vertebrates motoneurons of the spinal cord
			
		2. Cells in the caudate-putamen nucleus involved in motor coordination 
		
		3. PPT and LPT innervation of substantia nigra	

VIII.Octopamine OA
IX.Gating Proboscis Extension