Behavioral Neuroscience Summers

Sexual Behavior Reflexes Sensory Reception - Tactile Receptors Spinal Synapses Afferent Spinal Pathways

Hypothalamic Gating Efferent Motor Cascade Neuromuscular Production of Lordosis Integrated Story of Lordosis VIP Substance P Estrogens

5-HT GnRH ACh Lordosis figures   Sensory Receptors Spinal Cord   Lordosis Circuitry end     Acronyms/Abbreviations

LORDOSIS
VI. Spinal Synapses - Afferent Circuitry 	
!First Neural Circuit for a Mammalian Behaivor!

	A. Several Peptides plus serotonin (5-HT) are colocalized in the Pudendal
	   and Pelvic Nerves
	
	
		1. Vasoactive Intestinal Peptide (VIP)
		
			a. all inhibited by capsacin
			
			
				i. CRF  too
		
		
		2. Cholecystokinin (CCK) 
		
		
		3. Substance P (SP)
		
		
		4. Enkephalin (Enk)
		
		
		5. Somatostatin (GHRIH)
		
		
		6. All are present in the dorsal root
				
			
	B. Evidence suggests that VIP and SP
	   are stimulatory to lordosis


		1. dorsal root VIP/SP cells synapse onto interneurons
		
			a. stimulatory effect sent to motor neurons and brain
			
				i. ascending afferent signal reaches
				
					(1) lower brainstem module
					
					(2) midbrain module
					
					(3) hypothalamic module
		
		2. dorsal root VIP/SP cells synapse onto motor neurons
		
			a. VIP/SP signal to motor neurons not sufficient
			   to produce contraction of lateral longissimus
			   and transversospinalis muscles for lordosis 


				i. spatial summation of barrage of impulses
				   to dorsal root cells increases sensory impact
				  
				  	(1) but... it requires descending input
					    to be sufficient 
					

	C. Inhibited by Enk


		1. probably also somatostatin


		2. both via Gi blocking Adenylate Cyclase, cAMP, PKA, CREB


	D. Motor Synapses in the spinal cord drive lordosis


		1. summation of sensory and descending input
		
		
			a. descending input starts at the hypothalamus