Pheromones

Question 1

What are pheromones?

Answer 1

• molecules released by one animal to signal something to another member of the same species
• strongly influence the behaviour of many organisms

Question 2

Do pheromones exist in humans?

Answer 2

• their existence in humans is controversial

Question 3

Are behavioural responses to pheromones innate?

Answer 3

• yes, they are largely innate

Question 4

What are pheromones used to do?

Answer 4

• attract or repel other members of the same species
• signal attractiveness and sexual receptivity
• mark a path to follow
• signal danger

Question 5

Where are pheromones released?

Answer 5

• in liquid like urine or tears

Question 6

Where does the initial transduction and processing of pheromones occur in mammals?

Answer 6

• in the vomeronasal organ and accessory olfactory bulb

Question 7

Where are the vomeronasal organ and accessory olfactory bulb?

Answer 7

• next to but distinct from the regular olfactory epithelium and main olfactory bulb

Question 8

What are the regular olfactory epithelium and main olfactory bulb?

Answer 8

• process regular odors

Question 9

What are pheromones detected by?

Answer 9

• metabotropic vomeronasal receptors

Question 10

What are metabotropic vomeronasal receptors?

Answer 10

• distantly related to the olfactory receptors that detect normal odors

Question 11

Do humans have functional vomeronasal
organs?

Answer 11

• humans, apes, and birds do not have functional vomeronasal organs
• only have regular olfactory epithelium that detects normal odors

Question 12

How are pheromones detected?

Answer 12

• must be actively sniffed or tasted to be detected

Question 13

What does pheromone detection influence?

Answer 13

• sexual behaviour

Question 14

What is female to male pheromone signaling?

Answer 14

• how does female urine change male behaviour
• especially powerful
• male mice will only attempt to mate with female mice that are in heat

Question 15

What happens if the male vomeronasal system is damaged?

Answer 15

• they try to mate indiscriminately with any mouse, male or female

Question 16

What is male to female pheromone signaling?

Answer 16

• how does male urine change female behaviour
• effects are more subtle
• females prefer males that have healthy testosterone levels (vs. castrated males)
• presumably because of testosterone-induced male sex pheromone signaling

Question 17

What are the types of male to female pheromone effects?

Answer 17

• lee-boot effect
• whitten effect
• vandenbergh effect
• bruce effect

Question 18

What is the lee-boot effect?

Answer 18

• when female mice are housed together (without any male urine present), their estrous cycles slow down and eventually stop

Question 19

What is the whitten effect?

Answer 19

• pheromones in the urine of male mice can trigger synchronous estrous cycles in groups of female mice

Question 20

What is the vandenbergh effect?

Answer 20

• earlier onset of puberty seen in female animals that are housed with males

Question 21

What is the bruce effect?

Answer 21

• the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male

Question 22

What type of urine does not produce effects in female mice?

Answer 22

• urine of castrated males