Pheromones

Question 1

What are pheromones?

Answer 1

• chemicals released by animals

- elicit stereotyped behavioral/endocrine response in another animal of same species

Question 2

_____ detects pheromones

Answer 2

VNO (no cortical representation)

Question 3

chemicals enter through _________ and project to _______

Answer 3

• nasal/oral cavity

- amygdala

Question 4

Are pheromones found in humans?

Answer 4

no

Question 5

How many types of VNO receptors are there?

Answer 5

-2 V1Rs have about 200 members and V2Rs have about 70

Question 6

What is the transduction pathway for pheromones?

Answer 6

1. VNO receptors signal through IC pathway similar to taste, different PLC and different TRP channel used
2. TRPC2 expressed only in VNO, where protein is localized to sensory microvilli
3. TRPC2 essential for VNO response to pheromones

Question 7

What knockout eliminates electrical response to pheromones?

Answer 7

TRPC2 knock out-responsible for response of neurons to pheromones

Question 8

What happens when the VNO is silenced in males? (normal/castrated)

Answer 8

• male mouse (intruder) introduced to established mouse, resident attacks intruder (normal)
• attacks occur less frequently (castrated)

Question 9

What happens is castrated intruder is swabbed with pheromones from urine?

Answer 9

-he will again be attacked by resident

Question 10

Do TRPC2 KO mice attack intruders? why/why not?

Answer 10

• no

- consistent with the idea that they cannot sense the pheromones on the intruders

Question 11

What is a general response of TRP2 KO mice?

Answer 11

deficits in behavioral responses to pheromones

Question 12

TRPc males display _________

Answer 12

increased sexual behavior towards juveniles

Question 13

What do TRPC2 KO do?

Answer 13

-mate with intruders

Question 14

Why do TRPC2 KO try to mate with intruders?

Answer 14

• detection of pheromones by the VNO is necessary to allow male mice to discriminate gender
• in the absence of this information the default is to mate

Question 15

What do female TRPC2 KO show?

Answer 15

• male typical mating behavior

- seems like the lack of inputs somehow “masculinizes the brain.”

Question 16

Why don’t humans have pheromones?

Answer 16

-TRPC2 in humans is a pseudogene probably lost when trichromacy appeared