NBB 321 class 11

Female rodent proceptive behavior and attractivity

Wild rat burrows

In the wild rat live in burrows underground

• Mainly females and offspring live here, males are usually not welcomed and live on the surface

When females are ready to mate they come to the top

• Shows female proceptivity

Rat Proceptivity

Behaviors of female proceptivity

1. Approach males

2. Female orients towards male

3. Female runs away in a stereotypical fashion

   • Stiff-legged walk/run

   • Hops- short leap with the female landing on all four paws followed by assuming a crouching posture

   • Darts - run of several steps abruptly terminated by assuming a crouching posture

   • Ear wiggling- rapid vibration of head

   • Presents orients with rear end facing the male’s head

   • Posing- stands still in male line of sight

Female sexual solicitations in group-living rats

Full solicitations

• Hopping

Partial solicitations

• Touchback

• Runby

Interception

• Female takes male away from another female

Tethered male experiment

Their is male and a female in a cage but the male is tethered (tied up) and the female is free

The ovex female is given EB for 7 days and on the 8th day she is given P

• If the female was given no hormones then no lordosis or approaching would occur

• If the female is given EB then there is minimal proceptive and receptive behavior

• If female is given EB and P then you will see full proceptivity and receptivity

Females given EB and P approach the tethered male more, they show more proceptive and receptive behaviors

Female Preference for a stud over a dud

In experiment there are two tethered males (a stud- intact male & a dud- castrated male) and a free female

• When the female has no hormones she prefers to spend more time with castrated male

• When she is given hormones (EB and P) she spends more time with intact male

This behavior maybe because the female is getting an olfactory cue from intact male or because the male is making specific sounds

Hop/dart and approach frequency

Females primed with EB→P. Tested individually with stud, dud, or female

• Females with hormones had a higher frequency of hop/dart to stud males compared to dud or other females

• There approach frequency was higher with stud males compared to duds or females, however overall the approach frequency did not have significant change

Pacing Behavior

After an intromission, female withdraw to her burrow

• In laboratory pacing chamber, female can enter and exit male’s area through a small hole. He can’t enter her side

Female emerges and solicits male at predictable intervals

• She controls mating

Lengthens intervals between intromissions

Timing by female is dependent upon cervical-vaginal stimulation

Paced intromissions more effectively induce luteal function

• If a female paces mating then she is more likely to get pregnant

Comparison of female ovarian cycles in various species and the importance of male sexual behavior

Compared to other primates and non-primates, rats have an extended luteal phase after mating

• Same for rabbits and cats

Single level pacing chamber

In laboratory there is a cage divided into two sections, one for the male and one for the female

• There is a small hole at the bottom big enough only for the female, the female can approach male when she wants

• Female has control over intermission because of this hole

Bi-level pacing chamber female control of sex

In laboratory there is a cage or chamber in which both the female and male can stay in or exit when they want (acts as burrow)

• By moving to different locations in the cage the female can decide when to mate

5 or 10 paced intermissions and induction of pseudopregnancy (luteal progesterone) or pregnancy in female rate

Pseudopregnancy

• Female experiences an extended luteal phase but is not pregnant (could be because she mated with infertile male)

When female has control in pacing she is more likely to get pregnant or experience pseudopregnancy

Why hop and dart?

Males had brain lesions that lowered sex drive- MLR or SLR lesion

Females were either normal or hypokinetic

• Hypokinetic- rats that have reduced motor activity, they were treated with haloperidol so could not move or show proceptive behavior

• Hypokinetic rats still showed lordosis (receptive) but no proceptive behaviors

When male is with female that shows proceptive behavior, he is more likely to mate with them

• Male is more motivated if there is proceptive behavior

Female Hamster Proceptivity?

In experiment there is a free female and two hamsters, female and male, that are in smaller cages

• When female hamster is not in heat she spends time with both female and male in cage

• When she is in heat she will spend more time with male

  • She controls the pacing

Male attractivity varied with how male was housed

In experiment there are two hamsters in separate cages, a female and male, and a free hamster. In these smaller cages there is either holes or no holes

• When the female is in heat and there are holes in the smaller cages then the female will spend more time with male

• This is because of auditory senses

  • The male's attractiveness to the female varies depending on whether the smaller cages contain holes, facilitating auditory communication. When holes are present, the female, in heat, will prefer the male, while deafening her removes this discrimination.

Attractivity Cues

• Vocalization

• Olfactory Cues

Birdsong v. Male mouse song

Male birds sing more than females do because they are under the influence of testosterone. Its purpose is to:

• It attracts females

• Or defend territory

Mice also sing, we can’t really hear it but if we slowed it down it is similar to bird’s singing

Ultrasonic Vocalizations

Hamsters

• Both male and female hamsters emit ultrasonic call to attract conspecifics

• A second, distinct call is emitted by male only

• Male calling increases the duration of female lordosis and possibly inhibits female aggression

• Partially deafened females don’t show “proceptive” behavior towards males but will still be receptive

Male rats make a number of different calls- during mating series, preejaculatory call, and a postejaculatory call

• 50 kHz male mating call stimulates darting in females

• Preejaculatory call facilitates lordosis

• Both males and females call more to adult, intact, receptive mate

Male mice “sing” in response to females or odor cues from females (urine, vaginal secretion, even saliva-not estrus dependent)

• Male calls are androgen dependent

Attractvity in female rodents

In experiment there is a male in a cage and on the opposite side there are two cages he can choose to go

• In them there is either a female in heat or not

• Male can’t see them but can smell them because there is a fan behind the females’ cage to blow there scent to him

• He chooses to go to the female in heat based of olfactory cues

In dogs too, male attraction to female urine varies with her hormonal state

Dogs have a preference for females treated with E2 as opposed to those without

Summary (nonprimates)

Receptivity

• Follows endogenous ovarian and hormonal changes

• Peaks just prior to ovulation

• Progesterone alone does nothing

• Estradiol by itself produces weak receptivity

• Sequential E2 followed by P required for full receptivity

• P can block ability of E2 to prepare female for receptivity

Proceptivity

• Proceptivity is calling attention to self, increasing contact with partner, or vocalizations

• Follows female’s endogenous ovarian cycle

• E by itself increases the female’s interest in the male

• Full female proceptivity requires sequential E and P

• Female proceptivity stimulates male sexual responses

Attractivity

• Olfactory cues, or vocalizations

• Olfactory cues from vaginal secretions in females

• Estradiol alters vaginal secretions making female more attractive

• Progesterone may contribute to the full expression of female attractivity

• Behavior of both males and females contributes to their attractivity

Early studies of rhesus monkey sexual behavior used ‘pair-tests’

Put female and male in room to see if they will mate

• Female bears full weight of male when mating

• Males usually yawn when mating which shows his teeth

  • May to this as a way of telling others to back off

Occurrence of ejaculation in a ‘pair test’ in relation to female’s estradiol level

When a female has a high E2, the percent of males who ejaculate also increases

• In rodents this male percent of ejaculation is high near ovulation, small time period to reproduce

• In primates there is ejaculation everyday of the female cycle but it is higher when E2 is high

  • This may be because females may show more receptive and proceptive behaviors, or they’re more attractive

Female monkeys capacity to mate is not under hormonal control

In a lab (Emory) they introduced 5 new males during the non-breeding season

• The alpha female was seen mating with one of the new males even though there is 0 reproduction function

• It shows that primate mate for other reason other than reproducing, such as in this case for social status

  • The alpha female wanted to the male to become an alpha male so she mated with him

Lordosis strictly controls the ability to mate

Rodents can’t mate outside the breeding season because they physically can not go into lordosis

• An unreceptive female’s vagina opens downward

• Lordosis rotates the pelvis and elevates the vagina opening so that the male an intromit

Hormonally regulated mechanisms that control a female’s capacity to engage in sex

Lordosis

• Rodents, carnivores

Vaginal membrane

• Guinea pigs, prosimians

Immobilization

• Rats, hamsters, pigs

Does not exist in anthropoid primates (monkeys, apes, and humans)

Hypothesized mechanisms explaining why male sexual behavior varies with the female’s cycle?

Some possibilities may be:

• How female looks (attractivity) varies with her cycle influencing male sexual initiation

• How female smells (attractivity) varies with her cycle influencing male sexual initiation

• Female’s interest in sex with the male varies with her cycle influencing her sexual initiation (proceptivity)

• Female response to the male’s sexual initiation (receptivity) varies with her cycle influencing her willingness to engage in sex

Attractivity in monkeys can vary individually

Some male monkeys are considered more attractive than others

• This may be due to qualitative traits such as they are bigger in size

• Female 1 has a higher positive test( higher male % ejaculation) with male A and B and lower with male C

• Female 2 has a higher positive test with male C

• Females have a different preference with who to mate

Female looks different (Attractivity)

Changes in appearance with female’s cycle

1. Sexual swelling(happens when E2 is high)

   • Tonkean Macaque

   • Baboon sexual prosthesis

2. Sex skin color

   • Rhesus variation in sex skin color

All changes are due to hormones