Neurobiology, lecture on ACh
USD Department of Biology
Behavioral Neuroscience
Sexual Behavior
Sensory Reception - Tactile Receptors
Spinal Synapses
Afferent Spinal Pathways
Hypothalamic Gating
Efferent Motor Cascade
Neuromuscular Production of Lordosis Integrated Story of Lordosis
Substance P
Lordosis figures   Sensory Receptors
Spinal Cord   Lordosis Circuitry
end     Acronyms/Abbreviations
XII.  Acetylcholine (ACh)
		        I I
	A. substrates: choline and acetyl CoA
	              (diet)     (Glycolysis and Kreb's)
		1. synthetic enzyme: choline acetyltransferase (CAT)

			a. cytosolic   (most is synaptic)

			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. transmitter for: motor neurons of the spinal cord
	    \ all skeletal neuromuscular junctions

		1. all autonomic preganglionic neurons

			a. parasympathetic postganglionic neurons

		2. cells in the caudate-putamen nucleus involved in motor coordination 

		3. 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

		4. 2 specific populations in the limbic system

			a. septum to hippocampus  & habenulo-endopeduncular projections

			b. short axon striatal cells

	C. Muscarinic and Nicotinic Receptors 	(membrane proteins)

		1. M1 - M5

			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)асPLCасIP3 & Ca++

					(1) M3 stimulates VMN neurons 
					    projecting to MCG to stimulate lordosis
				ii. M2,4 cAMP

		2. Nicotinic

			a. four glycosylated peptide chains a, b, g, d in muscle
			b. neuronal only a & b

			c. ACh binds to the a subunit

				i. binding causes conformational change

					(1) allows cations, not anions, to pass

					(2) Ca++ passing stimulates muscular contraction
					    curving the spine during lordosis

XIV. Neuromuscular Function during Lordosis

XV. Integrated Vision of Lordosis