Prenatal stress effects: Are they mediated by reductions in maternal food and water intake and body weight gain?

Phystology& Behavtor, Vol 37, pp 191-193 Copyrtght©PergamonPress Ltd, 1986 Pnnted m the U S A

0031-9384/86$3 00 + 00

BRIEF COMMUNICATION

Prenatal Stress Effects: Are They Mediated by Reductions in Maternal Food and Water Intake and Body Weight Gain? 1 CRAIG KINSLEY z AND BRUCE SVARE 3

D e p a r t m e n t o f Psychology, State Umverstty o f NeIt' Yorl, at Albany, Albany, N Y 12222 R e c e i v e d 21 J u n e 1985 KINSLEY, C AND B SVARE Prenatal stress effects Are they rnedtated by redugttons m rnaternalfood and water mtake and body weight gam~ PHYSIOL BEHAV 37(1) 191-193, 1986 --Heat and restraint stress reduced maternal food and water retake as well as body weight gain m pregnant Rockland-Swiss (R-S) Albmo rmce Because maternal undernutntmn dunng pregnancy has been reported to disrupt SOClOSexualbehavior m male and female rodent offspnng, prenatal stress effects may be modulated, m part, by alterahons in essentml regulatory behawors of pregnant ammals Prenatal stress

Sexual d~fferenUat~on

Pregnancy

Food retake

Water retake

Body weight

GENERAL METHOD

P R E N A T A L stress (heat and restraint or overcrowding) in rodents disrupts the normal course of sexual differentiation and leads to alterations in SOClOSexualbehavior [11, 14, 16, 17, 19] The effects are pervasive and longlastlng, usually taking the form of demascuhnlzatlon 0 e , a reductmn m male-typical behaviors) and femlmzatlon (l e , an increase in the propensity to exhibit female-typical behaviors) [16] In male rodents, prenatal stress leads to reductions m copulatory behavior [16], mtermale aggression [5,10], and infanticide [15] In females, prenatal stress results m irregular estrous cycles, [8], and reductions in sexual responsweness [1, 8, 9], postpartum aggresslve behavior [12], maternal behavior [7,9], and fertflRy and fecundity [6] While studying the effects of prenatal stress (heat and restraint) on a variety of soclosexual behavmrs in mice [10], we noted that pregnant animals typically do not gmn as much weight d u n n g the stress period in comparison to undisturbed control animals Our observations, coupled with earlier reports (e g , [3,14]) showing that maternal food restriction and/or undernutrltlon alone are as effective as heat and restraint in causing deficits in offspring sexual responses, prompted us to systematically document the effects that heat and restraant stress have on maternal ingestive behaviors (food and water intake) and body wetght gain m pregnant mice

The subjects for the present experiment were RocklandSwiss (R-S) albino female mice born and reared m our colony at the State University of New York at Albany At 60 days of age the females were timed-mated by placing them with a stud male and checking for the presence of a copulatory plug every morning thereafter Upon discovery of a plug (GestaUon Day 0), the females were tsolated m 11 5x7 5×5 m polypropylene cages, the floors of which were covered with wood shavings The females were provided with ad lib access to food (Charles River Mouse Chow) and water The colony room temperature was maintained at a constant 24___2°C, with a 12/12 hr hght/dark cycle with lights on at 6 00 am On the morning of day 12 of gestation (R-S gestation length is 19 days), the females were weighed, provided with pre-welghed food cups (contamlng powdered Charles River Mouse Chow) and water bottles, and randomly assigned to one of three groups (N= 10/group) The first group of animals (Group STRESS) was exposed to heat and restraint stress according to the method of vom Saal [15] Briefly, this involved placing each female into a 3 25 x 1 125 m Plexlglas restraint tube over which were poised two 150 watt flood hghts This configuration produces 350 foot candles of fl-

~Thls work was supported m part by a grant from the Harry Frank Guggenhelm Foundation zCraig Kmsley now ~sat Laboratory of Human Reproduction and Reproductive B~ology, Harvard Medical School, 45 Shattuck St, Boston, MA 02115 aRequests for replants should be addressed to Dr Bruce Svare, Department of Psychology, State University of New York at Albany, 1400 Washington Ave , Albany, NY 12222

191

192

K I N S L E Y A N D SVARE TABLE 1 THE MEAN (-~S E M ) LITTER SIZES AT BIRTH, MEAN (-+S E M ) BODY WEIGHTS(GRAMS)AT BIRTH, AND MEAN (-S E M ) MATERNALBODY WEIGHTSAT PARTURITIONOF R O C K L A N D - S W I S S (R-S) ALBINO FEMALE MICE THAT WERE EXPOSEDTO HEAT AND RESTRAINTSTRESS FROM GESTATION DAYS 13 TO 18 (GROUP STRESS). NOT EXPOSEDTO STRESSBUT FOOD A N D WATERRESTRICTED (GROUP NON-STRESS),OR LEFT UNDISTURBED(GROUP CONTROL)

Group

N

Mean ( - S E M) Litter Size

STRESS NON-STRESS CONTROL

10 10 10

11 0 (-+1 6) 10 3 (+0 5) 11 7 (_+1 0)

Mean (_+S E M ) Litter Body Weight (Grams)

Mean (_+S E M ) Maternal Body Weight (Grams)

1 31 (+0 01)* 1 54 (-+0 01) 1 50 (-+0 01)

33 01 (-+1 86)* 36 84 (-+1 04) 36 15 (_+2 06)

*Slgmficantly different from Groups NON-STRESS and CONTROL, p<0 05

lumlnation and an ambient temperature within the restraint tube of 38°C The stress procedure was administered beginning on day 13 of gestation through day 18, for a total of six days There were three 30-minute stress sessmns each day at 8 3 0 a m , and 12 30 and 4 3 0 p m The second group of animals (Group NON-STRESS) simply had their food cups and water bottles removed from the cage for the same duratmn of time that Group STRESS did not have access to food and water (i e , for the three 30-minute sessions per day) This was done in order to control for the unavailability of food and water in Group STRESS during the time they were away from their cages The third group of animals (Group CONTROL) was not disturbed in any way except for the daily determinations of food and water retake and body weight Each morning prior to the first stress session each animal was weighed, and the amount (grams) of food and water consumed over the preceding 24 hours was recorded to the nearest 0 01 g At parturition, the females were weighed, and their htters were counted, weighed, and checked for the presence of any anomalies (dead pups, evidence of cannlbahsm, etc ) The mean body weight of each litter within each of the three groups was calculated and used as a single data point for the purposes of statistical analyses

~

7

2 z

5

4I 3i i

~-

i

I

f I

I

I

11

~

10

~ ~ ~

9

i a

~ ~ ~

$5 s3 51 49

~

47 4s

~ 0 ~

STRESSED O--O

NON STRESSED

43

RESULTS AND DISCUSSION Figure 1 depicts the results for food intake, water intake, and body weight over the course of Gestation Days 13-18 for animals of Groups STRESS, N O N - S T R E S S , and CONTROL It is evident from the figure that pregnant mice of Group STRESS exhibited reductions in ingestive behavior as well as body weight gain A one-way repeated measures analysts of variance (ANOVA) was performed on each of the three variables The A N O V A for food intake revealed significant main effects for treatment, F(2,27) = 17 3, p < 0 001, and days, F(5,135)=5 9, p < 0 001, as well as a significant treatment by days interaction, F(10,135)=5 6 , p < 0 001 Post hoc comparisons using the Flsher's Least Significant Difference Test (LSD) ( a = 0 05) indicated that there were no differences between the groups on the day prior to the adrmnlstration of stress (Gestation Day 13) On each gestation day thereafter, however, the animals of Group STRESS consumed significantly less food than the animals of either Group NONSTRESS or Group C O N T R O L Animals of Group NONSTRESS and Group C O N T R O L did not differ from each

41

13

14

I 15

I 16

I 17

l 18

Gestation Day

FIG 1 Mean dally food retake (grams) (top panel), water mtake (ml) (center panel), and body weight (grams) (bottom panel) of pregnant Rockland-Swiss (R-S) albino mice that were exposed to heat and restrmnt stress from Gestatmn Days 13 to 18 (Group STRESS), not exposed to stress but food and water restricted (see the General Method secUon) (Group NON-STRESS), or left undisturbed (Group CONTROL)

other on any gestation day with respect to the amount of food consumed A N O V A of the water intake data revealed a slgnLficant treatment by days interaction, F(10,135)=3 0. p < 0 002, but no significant main effects for treatment or days Post hoc tests showed that the groups did not differ with respect to water intake on Gestation Days 13 (prior to stress) and 17 Animals of Group STRESS, however, drank

STRESS AND M A T E R N A L I N G E S T I V E BEHAVIOR significantly less water on days 14, 15, and 18 of gestation than e~ther of the two control groups, which d~d not d~ffer from each other on the same gestation days On Gestation Day 16, ammals of Group STRESS drank less water than animals of Group NON-STRESS but not animals of Group CONTROL ANOVA of the body weight data revealed that there was no roam effect of treatment There was, however, a s~gnlficant main effect of days, F(5,135)=543 4, p < 0 0001, as well as a stgmficant treatment by days interaction, F(10,135)=9 0, p < 0 001 Post hoc tests revealed that there were no d~fferences in body weight between the groups on the day prior to stress (Gestation Day 13) For every gestation day thereafter, though, ammals of Group STRESS weighed stgmficantly less than ammals of both control groups Ammals of Group NON-STRESS d~d not slgmficantly differ from ammals of Group CONTROL on Gestatton Days 13, 14, and 15 Begmmng on Gestation Day 16, however, and continuing untd Day 18, ammals of Group NONSTRESS weighed s~gmficantly less than animals of Group CONTROL Th~s indicates that e~ther fadure to have access to food and water for the three half-hour periods, or some aspect of removing the food cups and water bottles, may have been stressful to the pregnant m~ce on those days Table 1 shows the data for htter size and htter body weight at b~rth, and maternal body weights at parturmon for animals of Groups STRESS, NON-STRESS, and CONTROL There was no d~fference among the three groups m the number of pups present at b~rth There was, however, a pronounced effect on the average body weight of the litter An ANOVA on these data revealed a slgmficant treatment effect, F(2,27)=5 6, p < 0 009, and post hoc tests showed that pups of Group STRESS exhibited s~gmficanfly lower birth weights than did neonates of the other groups, Groups NON-STRESS and CONTROL d~d not d~ffer from each other with respect to the b~rth wetghts of pups ANOVA also showed a s~gmficant effect of treatment on maternal body

193 weight at parturition, F(2,27)=7 2, p <0 003 Post hoc tests revealed that ammals of Group STRESS were rehably hghter than animals of either Groups NON-STRESS or CONTROL, which were not slgmficantly dLfferent from each other There was no evidence of dlfferentml pup mortality or other observable anomahes Prenatal stress effects on rodent soclosexual behawors are thought to be medmted, at least in part, by alterations m fetal and/or maternal endocnne function For example, prenatal stress alters the timing of fetal testosterone secretions [ 17,18], disrupts aromatizing enzyme aCtlVlty[ 19], and alters the morphology of the sexually-dlmorphlc nucleus of the preopUc area (SDN-POA) [2] Studies also show that the offspring of nutnUonally stressed (food restricted) pregnant rats exhibit disruptions m copulatory behavior and reducUons m the s~ze of the SDN-POA that are very slmdar to those documented for heat and restrmnt stress [2,14] In conjunction with the above effects on the fetus, undernutnt~on during pregnancy also leads to acute reductions in maternal levels of progesterone and the gonadotropms m pregnant rats and mice (e g , [4,13]) These findings, m combination with our own results showing reduced maternal mgesttve behaviors (food and water retake) and body weight m pregnant m~ce, raise interesting questions regarding the actual mechamsm responsible for environmentally produced (heat and restraint or overcrowding) prenatal stress influences on behawor Do reductions m maternal ingestive behawor and body weight represent ummportant correlates of environmental stress during pregnancy9 Or, on the other hand, do such changes following stress sUmulate or act m concert with the well-documented hormonal changes that occur m the fetus and the gravld female At the very least, changes m the regulatory behaviors exhibited by pregnant females must be taken into account when developing comprehensive theories to expimn prenatal stress effects on the development of sooosexual behaviors in rodents

REFERENCES 1 Allen, T O and B N Haggert Group housing pregnant mice reduces copulatory recephwty of female progeny Phystol Behav 19: 61-68, 1977 2 Anderson, D K , R W Rhees and D E Fleming Effects of prenatal stress on dlfferentmtton of the sexually dlmorph~c nucleus of the preopnc area (SDN-POA) of the rat brmn Brain Res 332. 113-118, 1985 3 Francova, S Effect of protein-caloric malnutnUon on the development of social behavior m the rat Dev Psychobtol 6. 33--43, 1973 4 Gmnnma, T , and J H Leathem Serum progesterone levels m pregnant rats fed a protein-free d~et Proc Soc Exp Btol Med 146" 957-960, 1974 5 Harvey, P W and P F D Chevms Crowding pregnant mice affects attack and threat behawor of male offspnng Horm Behav 19" 86-97, 1985 6 Herrenkohl, L R Prenatal stress reduces fernhty and fecundity m female offspnng Science 206 1097-1099, 1979 7 Herrenkohl, L R and R R Gala Serum prolactm levels and mmntenance of progeny by prenatally-stressed female offspring Expertenna 35: 702-705, 1979 8 Herrenkohl, L R and J A Pohtch Effects of prenatal stress on the estrous cycle of female offspnng as adults Expenent~a 23" 1240-1241, 1978 9 Herrenkohl, L R and J B Whitney Effects of prepartal stress on postnatal nursing behawor, htter development, and adult sexual behawor Phystol Behav 17. 1019-1021, 1976 10 Kmsley, C and B Svare Prenatal stress reduces the mtermale aggression m mice Phystol Behav, m press

11 Masterpasqua, F , R H Chapman and R K Lore The effects of prenatal psychological stress on the sexual behavior and reactivity of male rats Dev Psychoblol 9 403--411, 1976 12 Pohtch, J A and L R Herrenkohl Prenatal stress reduces maternal aggression by mice offspnng Phystol Behav 23. 415418, 1979 13 Rattner, B A , S D Michael and H F Bnnkley Plasma gonadotrophms and progesterone concentrations dunng vanous degrees of underfeeding m pregnant mice J Reprod Fertd 56 587-591, 1979 14 Rhees, R W and D E Fleming Effects of malnutnnon, maternal stress, or ACTH mjecUons dunng pregnancy on the sexual behavior of male offspnng Phystol Behav 27" 879-882, 1981 15 vom Saal, F S Variation m mfannclde and parental behavior m male mice due to prior mtranterlne proximity to female fetuses Ehmmatton by prenatal stress PhysloIBehav 30: 675-681, 1983 16 Ward, I L Prenatal stress feminizes and demascuhmzes the behavior of males Sctence 175 82-84, 1972 17 Ward, I L and J Welsz Maternal stress alters plasma testosterone m fetal males Scwnce 207 328-329, 1980 18 Ward, I L and J Wetsz Differential effects of maternal stress on c~rculatmglevels of cort~costerone, progesterone, and testosterone m male and female rat fetuses and their mother Endocrinology 114" 1635-1644, 1984 19 Welsz, J , B L Brown and I L Ward Maternal stress decreases steroid aromatase activity m brains of male and female rat fetuses Neuroendocnnology 35 374-379, 1982