Developmental Psychobiology 2001

1

• Developmental Psychobiology (2001)
• 39 19-33
• Samantha Chui

2
QUESTION

• What deficits do maternally separated rats show
  in juvenile and adult maternal behaviour?

3
Hormones

• Maternal behaviour is initially under the control
  of hormones associated with the end of pregnancy
  and parturition (decreases with time after
  parturition)
• Maternal behaviours can include
• Pup body licking
• Pup retrieval
• Nursing

4
Virgin Rats

• Initially avoidant towards foster pups
• If continually exposed (SENSITIZATION), will show
  full repertoire of maternal behaviours
• Juvenile rats (18-30 days old) also show maternal
  behaviour when exposed to foster pups
• THEREFORE Neither steroid nor pituitary hormones
  are necessary for the display of maternal
  behaviour.

5
Early Life Experiences- Early life attention -

• Amount of licking received from the mother is
  positively correlated with the amount of licking
  these offspring (as adults) show toward their
  newborns

6
- Early life separation -

• Brief separation is beneficial, NOT because of
  absence of maternal attention, but rather by the
  increase in attention given when the pups are
  reunited with their mother
• Prolonged periods of separation are often
  accompanied by nutritional loss, body temperature
  loss and less overall licking

7
Purpose

• To assess whether early-life maternal separations
  disrupt the display of adult maternal behaviour
• To assess whether early-life separation from
  mother disrupt the display of juvenile maternal
  behaviour

8
General Procedure

• Rat female pups were either separated (SEP) from
  their mothers for 5 hr daily from 1 to 17 days of
  age or left with their mothers (NSEP)
• As juveniles received either contact with pups
  (P), with a same aged con-specific (S), or no
  social cues (I) for 5 consecutive days
• In adult hood, animals were assessed for their
  maternal behaviour after the birth of their
  litters

9
Procedure

• 1. Neonatal experimental manipulations (between
  Day 1-17)
• Each litter culled to 6 female, 6 male
• Within the 6 females
• SEP 3 pups to undergo the separation procedure,
  5 hours per day
• NSEP 3 pups non-separated
• Tested on an elevated plus-maze on Day 21

10
Elevated plus maze
11

• 2. Juvenile experimental manipulations (between
  Day 22-27)
• 1 pup from NSEP and SEP in each litter were
  randomly assigned to 1 of 3 conditions
• I isolation from all other pups
• S having a same-age playmate
• P daily exposure to 1-4 day old pups pups left
  with subject overnight and replaced with freshly
  fed pups for the test the next day
• Tested on the elevated plus maze then housed in
  pairs

12

• 3. Adult experimental manipulations (Day 70 and
  up)
• Mated between Day 70 to 100
• At time of parturition, pups were removed within
  15 min of each birth to prevent mothers from
  having maternal experience
• Assessed for maternal behaviour on 5 consecutive
  days FOUR days after birth (to prevent early life
  manipulations from being masked by parturitional
  hormones)

13
Juvenile Maternal Behaviour

• Assess for maternal performance toward foster
  pups over the 5-day period
• Maternal behaviours consisted of
• Retrieval of pups
• Licking of pup bodies
• Licking the anogenital region of the pups
• Crouching
• Nest building

14
- Pup Body Licking -

• SEP juveniles spend less time licking pups than
  NSEP juveniles, F(1,15) 4.964, p

15
- Nest Building -

• SEP juveniles spend less time nest building than
  NSEP juveniles F(1, 15) 5.87, p
• Other behaviours showed no separation effect but
  did show significant increases

16
Adult Maternal Behaviour

• Assessed for maternal behaviour toward foster
  pups 4 days after parturition
• Maternal behaviours consisted of
• Retrieval of pups
• Licking of pup bodies
• Licking the anogenital region of the pups
• Crouching
• Nest building

17
- Pup body licking -

• Significant effects of separation on pup body
  licking F(1, 41) 4.167, p
• NSEP subjects spent more time engaging in this
  behaviour

18
- Crouching over pups -

• Significant effects of separation on crouching
  over pups F(1, 41) 77.976, p
• NSEP subjects spent more time engaging in this
  behaviour

19
NSEP Isolates

• NSEP isolates performed at about the same level
  as the three groups of SEP animals
• SEP isolates did not show reduced maternal
  behaviour
• Pups were isolated for only 5 days

20
Emotionality

• NSEP isolated group spent significantly less time
  in the open arms than did either of the other
  NSEP groups or any of the SEP groups

21

• If animals that have already experience
  separation during early prewearning period, an
  addition separation during juvenile period is
  less deleterious

22
REMINDER
What deficits do maternally separated rats show
in juvenile and adult maternal behaviour?
23
ANSWER

• Maternally separated rats (SEP) spend
• Less time pup-body licking and nest-building as
  juveniles (although these results were minimal)
• Less time pup-body licking and crouching over
  pups as adults
• Isolated juveniles show deficits in adult
  maternal behaviour when compared to non-isolated
  juveniles

24
Thank You!