Alcohol exposure during development alte

Alcohol exposure during development alters social recognition and social communication in rats.. NEUROTOXICOL TERATOL 195 383-389,1997.-The present study examined the effects of postna

Alcohol

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Social Recognition and Social

Department of Psychology, University of South Carolina, Columbia, SC 29208

Received 16 August 1996; Accepted 11 May 1997

KELLY, S J AND T D TRAN Alcohol exposure during development alters social recognition and social communication

in rats NEUROTOXICOL TERATOL 19(5) 383-389,1997.-The present study examined the effects of postnatal alcohol

exposure via gastric intubation on social communication of diet preference and social recognition Rats were placed in one of

three treatment groups All treatments occurred from postnatal day (PD) 2 through 10 and Experiments 1 and 2 were con-

ducted when the rats reached 60 and 100 days of age, respectively Alcohol-exposed pups received a 3.0 g/kg dose of ethanol

in milk solution that was delivered by insertion of PE-10 tubing down the esophagus daily from PD 2 through 10 Intubated

control animals underwent intubation without ethanol or milk Nontreated control pups were weighed daily In Experiment 1,

a nonexperimental rat was initially given access to lab chow mixed with a spice and then housed with an experimental rat for 30

min The experimental rat was subsequently given access to two diets-one that the nonexperimental rat had consumed and a

novel diet It was found that the alcohol-exposed females consumed a greater percent of the communicated diet than the con-

trol females In Experiment 2, the experimental rats were first exposed to a juvenile for 5 min and then exposed to the same

juvenile after a delay of 30 or 90 min Investigation time was recorded in both sessions and a reduction of investigation time in

the second session is an indicator of social recognition memory Alcohol-exposed rats of both sexes had poorer memory of a

juvenile than both control groups after a 90.min delay Together, these data indicate that basic components of social behavior

may be altered by alcohol exposure during development o 1997 Elsevier Science Inc

Postnatal ethanol exposure Fetal Alcohol Syndrome

Social communication Gastric intubation

Social behavior Social recognition

THE central nervous system deficits that are central to Fetal vestigations of effects of alcohol exposure during develop- Alcohol Syndrome (FAS) can be manifested as changes in ment on components of social behavior in rats Rats exposed cognition, emotionality, and behavior (29,30,32) Social be- to alcohol during the prenatal period show reductions in the havior is vital for adaptation to the environment and deficits number of ultrasonic vocalizations when isolated from their

in social behavior can hinder one’s performance in many fac- mothers (24), and rats exposed to alcohol during either the ets of life including work and school Adolescents and adults prenatal or postnatal period take longer to attach to a nipple with FAS continue to be markedly impaired on socialization compared to controls (1,26) Males typically show higher lev- skills such as failure to consider consequences of one’s own els of play than females (21), but this sexually dimorphic ef- actions and lack of reciprocal friendships, as measured by the feet is reversed when rats are given alcohol prenatally (22) Vineland Adaptive Behavior Scale (31), even when there are Furthermore, juvenile rats prenatally (2) or postnatally (38)

no longer deficits in I.Q (31) Indeed, deficits in social behav- exposed to alcohol show an increase in the latency to retrieve ior in children with FAS are much greater than those seen in rat pups Adult female rats prenatally exposed to alcohol also children matched for I.Q without FAS (33) exhibit less pup-induced maternal behavior (2) Male adult Although social behavior in animals is not as complex as in rats normally strongly prefer receptive females to other males; humans, considerable knowledge has been gained through in- prenatal alcohol exposure attenuates this preference differ-

Requests for reprints should be addressed to Sandra J Kelly, Department of Psychology, University of South Carolina, Columbia; SC 29208 Fax: (803) 777-9558; E-mail: kelly@garnet.cla.sc.edu

383

ence (7) Finally, although adult males normally interact more

frequently than adult females, this effect is reversed in rats

that have been exposed to alcohol during the early postnatal

period (19)

To continue the characterization of the changes in the dif-

ferent components of social behavior induced by alcohol ex-

posure during development, this study focused on two social

behaviors The first type of social behavior, social communi-

cation of diet preference, requires the animal to process social

cues while its performance is motivated by nonsocial de-

mands A rat is fed an unusual food and then allowed to inter-

act with an experimental rat for a brief period of time The ex-

perimental rat is then allowed to choose between two types of

food mixes-one of which the other rat had consumed and

one of which is novel The experimental rat shows a prefer-

ence for the food that had been consumed by the other rat

(16) This preference does not occur by mere exposure to the

odor of the diet: the preference is only formed when the expo-

sure to the diet odor occurs in the presence of another awake

rat (14,lS) To examine any general alterations in responsivity

to odor and taste cues, this experiment also examined taste

aversion learning

The second type of social behavior examined is social rec-

ognition memory This task involves briefly exposing an adult

rat to a juvenile, removing the juvenile from the testing envi-

ronment for a stipulated period of time, and reexposing the

adult to the same juvenile (34) The adult rat has formed a so-

cial memory for the juvenile if the amount of investigation is

reduced in the second exposure compared to the first expo-

sure Reductions in investigation time do not occur when a

different juvenile is presented in the second exposure, sug-

gesting that the recognition memory is specific for the individ-

ual juvenile and that the reduction in investigation time when

the same juvenile is used is not the result of habituation to the

situation Social recognition memory is sexually dimorphic

with respect to both the behavior (4) and the neural bases

(4,s) Given that alcohol exposure during the early postnatal

period affects active social interactions, another sexually di-

morphic social behavior it seemed probable that this behav-

ior would show effects as well

The animal model of FAS used in this study entails gastric

intubation during the early postnatal period, in a manner sim-

ilar to Serbus et al (28) The postnatal period was chosen be-

cause, during this period, the brain undergoes a period of

rapid growth (12) and thus, may be particularly vulnerable to

the effects of alcohol (36) This period is equivalent to the lat-

ter portion of the second trimester and all of the third trimes-

ter in humans with respect to brain growth (3) Traditionally,

investigations of postnatal alcohol effects have relied on an

artificial rearing procedure: however, this procedure results in

a very artificial social experience early in life and seemed

likely to alter social behaviors by itself In contrast, gastric in-

tubations allow the pup to receive maternal care and milk and

to have contact with its siblings Thus, the decision was made

to use gastric intubations rather than artificial rearing to mini-

mize effects of administration procedures while investigating

the effect of alcohol exposure during development on social

communication and social recognition in rats

METHOD

Subjects

Fifty-seven Long-Evans rats were used as experimental

subjects and were housed in the animal colony in the Depart-

ment of Psychology at the University of South Carolina Food

and water was available ad lib and lighting was maintained on

a 12:12 h 1ight:dark cycle with the light phase beginning at

0700 h All testing was conducted during the second half of the light phase

Experimental animals were bred in the colony at the Uni- versity of South Carolina Parent animals were Long-Evans female breeders (90 days of age) and were housed with male breeders overnight Vaginal smears were collected the follow- ing morning and positive samples indicated gestational day 1

of pregnancy Offspring from eight litters were randomly as- signed to one of three treatment groups on PD 2 There were never more than two rats from the same litter in each group and each litter had pups from all three treatment groups Lit- ters were culled to 10 pups Treatment groups consisted of

an ethanol-intubated (EI) intubated-control (IC), and a non- treated-control (NC) group Subject numbers are shown in Table 1

From PD 2 through PD 10, animals in the EI group were weighed and then intubated with 3 g/kg of ethanol in a volume

of 0.0278 ml/g of milk formula (37) followed by 0.0278 ml/g of milk formula alone 2 h later The second feeding of milk was done to compensate for any weight loss resulting from alcohol intoxication Intubations were implemented using clear PE-IO tubing connected to a shorter section of PE-SO tubing that was attached to a 26-gauge needle The end of the tube was dipped in corn oil and the tubing was inserted down the ani- mal’s esophagus until it had reached the stomach IC rats un- derwent similar intubation procedures as the El group, but did not receive the alcohol or the milk and animals in the NC group were weighed and did not receive either the intubations

or alcohol The intubation process took 2 min after which the pup was returned to its dam

Blood alcohol concentrations (BACs) were taken on PD 6,

90 min after the end of the first intubation Blood samples were taken from both EI and IC rats The tip of the animal’s tail was severed with a fine blade, and 10 p_l of blood was drawn into a capillary tube The blood was then placed in 190 ~1 of 0.52 N perchloric acid and neutralized with 200 ~1 of 0.30 M potassium carbonate Samples were centrifuged (Beckman Microfuge E)

on high for 15 min and were refrigerated (4°C) All samples and ethanol-containing standards were assayed for alcohol con- tent using an enzymatic procedure (13)

On PD IO all pups were paw-marked with permanent ink for later identification (17) All pups were weaned on PD 21 and housed in same-sex pairs until the time of behavioral test- ing, which was at 60 and 100 days of age All behavioral test- ing was conducted blind to the treatment group

Experiment I: Sociul Communication und Taste Aversion Leurning

The social communication test was a modification of the test by Galef and Stein (15) The testing for both social com- munication and taste aversion utilized two diet pairs-either cinnamon and cocoa or anise and marjoram The diets were made by mixing 2 g of marjoram, 2 g of cocoa, 1 g of cinna- mon, or 1 g of anise with 100 g of powdered rat chow The spices were McCormick brand and powdered Within a test, the diet pairs and the diet to be communicated or to be fol- lowed by LiCl were counterbalanced across groups and sexes

In the taste aversion testing the experimental rat was tested with the diet pair that had not been used in the social commu- nication test for that particular rat Large and small hanging cages used in the tests were 24.0 W X 67.5 L X lY.0 H cm and

24 W X 19.5 L X 19.0 H cm respectively

Until the time of testing, the experimental rats were housed

in same-sex pairs in plastic cages with free access to food and

water On postnatal day 60, the experimental rat was moved

into one side of a large hanging wire cage divided into two

equal halves by wire mesh The experimental rat was given

free access to water rat pellets, and two bowls of plain pow-

dered rat chow The bowls were 3.5 cm deep, 5 cm in diame-

ter, and bolted to the floor On the other side, an unfamiliar,

nonexperimental rat of the same sex and approximately the

same weight was housed and given free access to water only

For two consecutive pretest days, the nonexperimental rat

was removed from the partitioned cage after 23 h of food dep-

rivation to a small hanging wire cage, given free access to

powdered rat chow in a small bowl for 1 h, and then returned

to its half of the partitioned cage

On the third day, which was the test day, the nonexperi-

mental rat was given access to 2.5 g of a flavored diet that was

to be communicated for 1 h after 23 h of food deprivation

The rat was then returned to the same side of the partitioned

cage as the experimental rat for 30 min and then removed

from the partitioned cage entirely After the 30 min of inter-

action with the nonexperimental rat, the experimental rat was

given access to 25 g of the communicated diet and 2.5 g of the

other member of the diet pair (e.g., cinnamon vs cocoa or

marjoram vs anise) in two small bowls The regular rat pellets

were removed from the cage After 24 h, the amount of each

diet consumed was determined The experimental rats were

returned to their prior housing conditions in same-sex pairs

On postnatal day 67, the experimental rat was placed into

a small wire cage with two empty bowls in it The rat had free

access to water but had access to plain powdered rat chow in

the bowls for only 1 h after 23 h of food deprivation Then, af-

ter a further 23 h of food deprivation, the rat was given access

to a flavored diet for 1 h The rat was then injected with 2%

(w/v) solution of LiCl in a volume of 1% body weight

Twenty-four hours later the rat was given access to 25 g of the

flavored diet paired with LiCl and 25 g of the other member

of the diet pair The amount of each diet consumed over 24 h

was measured The experimental rats were returned to their

regular housing conditions

Experiment 2: Social Recognition

Social recognition testing was a modification of that done

by Sawyer et al (27) and began when the animals reached 100

days of age Animals were tested during the latter half of the

day portion of the light cycle (1400-1700 h) Females were

tested only during diestrus, a stage in which hormonal levels

are relatively stable: daily vaginal smears verified the stage of

estrus There were 3 test days, which were not necessarily con- secutive, and each test day consisted of two sessions of 5 min each Prior to each session, the experimental adult rat was placed in a cage containing fresh bedding For each test day, the experimental rat was exposed to a novel juvenile rat (21-

30 days old) for 5 min in the first session and then returned to its home cage The same juvenile was used in the second ses- sion following an interval of 90 min on test day 1 and 30 min

on test day 2 On the third test day, a novel juvenile was used

in the second session, which occurred after a 30-min interval The third test day was done as a control test, which would de- tect any group differences in habituation or reactivity to the juvenile in the second session that might confound the mea- surement of recognition memory

Investigation time (in seconds), which included both sniff- ing and grooming, was recorded using an S&K Event Re- corder (NEC model 100) in all sessions

Statistical Analyses

Because the appropriate comparisons were known at the time of the design of the experiment, analyses of variance (ANOVA) followed by planned orthogonal comparisons were conducted on the behavioral data (20,39) Within each sex, the IC and NC groups were compared and if these groups did not differ from each other, then the EI group was com- pared to the two control groups A comparison between sexes was also conducted For the BAC data, a t-test comparing the sexes in the EI group was conducted The planned compari- sons were orthogonal to each other and, because orthogonal- ity controls for repeated tests, significance was assumed at the 0.05 level for all analyses (21) Two repeated measures ANOVAs were conducted on the body weight data from PD

2 through 10 and then on the body weight data on PD 10, PD

21, PD 30, and PD 60 F,,,,, tests were used to compare the variances between the sexes in the behavioral tests All error bars and error terms are SEMs

RESULTS

Physical Parameters

The body weights of the groups on PDs 10,21, and 60 and blood alcohol concentrations are depicted in Table 1 For both

of the ANOVAs conducted on the body weight data, there were no effects of or interactions with group, indicating that none of the treatments had an effect on body weight There were significant interactions of sex and day in the body weights from PD 2 through 10, F(8, 400) = 6.79, p < 0.001, and from

PD 10 through PD 60, F(3, 153) = 268.51, p < 0.001, such that

PHYSICAL PARAMETERS AND SUBJECT NUMBERS (MEANS AND SEMs)

Body Weights at Treatment Group Sex Subject Number PDlO PD2 I PD6U BACs (mgidl)

Ethanol-intubated female 8 21.9 2 0.7 50.1 2 1.2 228.5 k 5.2 267 -c 35

male 10 24.3 2 1.1 57.1 5 2.2 357.0 2 7.7 242 -t 27 Intubated-control female 11 22.1 t 0.7 52.1 t 1.4 221.9 + 3.4 0

male 9 26.0 ? 1.1 60.3 2 2.1 362.0 2 8.7 0 Nontreated-control female 10 22.9 2 0.8 53.9 i- 1.7 252.9 2 9.1 0

Females Males

Ethanol-

ii?l SZ

Intubated- Nontreated-

FIG 1 Mean percentage 2 SEM of communicated food consumed by ethanol- intubated, intubated-control, and nontreated-control rats EI females consumed sig- nificantly more communicated food than both IC and NC females

the difference in weight between the sexes became greater as

they became older There were no significant differences be-

tween the sexes with respect to blood alcohol concentrations

Social Communication and Taste Aversion

ANOVA indicated that there was a significant interaction

of group and sex, F(2,52) = 3.50, p < 0.05, on the amount of

communicated food consumed as a percent of total amount

consumed Among females, EI rats consumed more commu-

nicated food than the NC and IC female rats, F(l, 52) = 9.23,

p < 0.01, which did not differ from each other (see Fig 1)

There were no differences among male groups or any overall

sex difference in percent of communicated food consumed

(see Fig 1) There were no differences among groups with re-

spect to total amount of food consumed by their paired non-

experimental rat However, there was a significant interaction

between group and sex, F(2, 52) = 4,61, p < 0.05, in total amount of food consumed Female EI rats consumed signifi- cantly less than the total amount consumed by the NC or IC female rats, F(l, 52) = 10.34, p < 0.01, which did not differ from each other (see Table 2) There were no differences among the male rats with respect to total amount of food con- sumed (see Table 2) There was an overall sex difference in total amount consumed such that males consumed more food than females, F(l, 52) = 48.62, p < 0.001 An F,,,,, test indi-

cated that the variance of the female data did not differ from the variance of the male data

All of the groups showed aversion to the diet paired with the LiCl injection; however, there were no main effects of nor interactions with groups with respect to the degree of aversion (as measured as percent of total amount consumed of the paired diet) (see Table 2) In general, females showed greater aversion

than males, F(l, 52) = 10.78, p < 0.01 There were no effects of

FOOD CONSUMED IN SOCIAL COMMUNICATION TASK (IN GRAMS) AND PERCENT OF FOOD CONSUMED THAT WAS PAIRED WITH LICL IN

TASTE AVERSION TASK (MEANS AND SEMs) Treatment Group Food Consumed Food Consumed Percent

Communicated* Novel* Consumedt

Ethanol-intubated female 12.2 % 1.1 3.2 t 0.9 21.3 t 2.6

male 19.5 + I.6 12.6 t 1.1 30.5 -t 6.2 Intubated-control female 13.5 t 1.1 10.4 t 1.5 24.3 + 5.2

male 18.8 2 1.1 12.4 i 2.3 32.3 t 7.3 Nontreated-control female 15.0 + 1.3 10.3 I!I 1.4 24.8 + 6.2

male 17.8 2 1.2 13.3 + 1.4 37.7 i- 6.6

*These data are the raw data from the social communication task and are graphed as percents in Fig 1

TThese data are the percent of total food consumed that was paired with LiCl

or interactions with group with respect to total amount of food

consumed prior to injection of LiCl and the total amount of

food consumed after the injection of LiCl There was an overall

sex difference in both total amount measures such that males

consumed more food than females, F(l, 52) = 55.12, p < 0.001;

F(l, 52) = 43.45,~ < 0.001 There was no difference in variance

between the sexes, as indicated by an F,,, test

showed greater proportional scores than females on test day

2, F(l, 52) = 8.01, p < 0.01 There were no differences be- tween the sexes in the variance in the proportional scores on any of the test days, as indicated by an F,,,,, test

DISCUSSION

Social Recognition

An examination of investigation times for the first session

only collapsed across the 3 test days revealed that males spent

more time investigating a novel juvenile than females, F(1,52) =

51.18, p < 0.001 The means (in seconds) and SEMs for the first

session investigation times for males and females were 93.5 ?

4.8 and 40.2 2 2.4 There were no main effects of or interac-

tions with group To examine whether there was social recog-

nition of juveniles during the second session of testing, pro-

portional scores were obtained by dividing the second session

score by the first session score A proportional score of 1.0 in-

dicates that an animal has no memory for the previously en-

countered juvenile and proportional scores less than 1.0 indi-

cate that a memory of the juvenile was retained

An ANOVA indicated that there was a trend towards a sig-

nificant effect of group on day 1 of testing (90-min interval,

same juvenile in each session), F(2, 52) = 2.72, p = 0.07

Planned comparisons indicated that EI rats showed greater pro-

portional scores than the combined control animals, F(1, 52) =

5.90, p < 0.05, which did not differ from each other (see Fig 2)

Day 2 (30-min interval, same juvenile in each session) analyses

revealed no significant differences in proportional scores among

groups Day 3 (30-min interval, different juvenile in each ses-

sion) analyses revealed no significant differences in propor-

tional scores among groups There were no interactions of sex

and group on any of the test days There were no main effects

of sex on proportional scores on test days 1 and 3 but males

Alcohol exposure during the early postnatal period causes

an enhanced responsiveness to social communication of diet preference in females This result was not expected In hind- sight, it might have been predicted from the prior finding that alcohol-exposed females show an increase in frequency of ac- tive social interactions (19); it may be that the increased fre- quency of active social interactions translates into increased responsiveness to social cues However, it should be noted that untreated males have a greater frequency of active social interactions than untreated females (19) yet there were no dif- ferences in responsiveness in social communication between the sexes Thus, it is not a simple translation of increased fre- quency to increased responsiveness Furthermore, the taste aversion learning was the same among groups so the increase

in responsiveness to social communication cannot be a simple increased responsiveness to odor cues

A number of hypotheses can be made about the increased responsiveness to social communication in alcohol-exposed females One hypothesis is that the alcohol exposure alters the nervous system such that the females are hyperresponsive to all social cues; however, there is at least one social behavior, namely maternal responsiveness as measured by retrieval of pups, in which alcohol exposure appears to result in less responsiveness (2,38) It may be that the increase in responsive- ness is restricted to social cues from other adults or is a general hyperresponsiveness to all stressful situations that manifests itself differently in maternal and adult-adult social interactions This last explanation might also account for the overall decrease

DAY 1

Ethanol- lntubated

Intubated- Control

Nontreated- Control

FIG 2 Mean proportional scores k SEM of adult rats across the 3 days of testing EI rats had significantly higher proportional scores than both IC and NC groups during the first test day (90-min interval, same juvenile in both sessions) No differences were found among groups for the second (30-min interval, same juvenile in both sessions)

in food consumption seen in the alcohol-exposed females An-

other hypothesis is that the motivational aspects of the social

communication scenario, namely motivation to learn about food

sources and the motivation to respond to social cues is different

in the alcohol-exposed female rats However, there is some evi-

dence suggesting that alcohol exposure reduces food motiva-

tion (6.23) and the alcohol-exposed females in the present

study consumed a smaller overall amount of food, at least dur-

ing the social communication study These findings make it un-

likely that an increased motivation for food is the cause of an

increase in responsiveness

A final explanation of the effect of alcohol exposure on so-

cial communication is that this effect occurs because this form of

social learning, which requires the animal to be able to form a

preference for a diet because of its odor being in the presence of

a live conspecific, is quite complex and possibly too demanding

for the alcohol-exposed females (14-16) Interestingly, although

the finding of no alcohol-induced changes in adult acquisition of

taste aversion is consistent with others (6.25), it has been found

that retention of taste aversion is impaired in alcohol-exposed

animals (6) This suggests that there is some alcohol-induced al-

teration in the ability to form associations that is fairly subtle It

may be that the sheer complexity of the social communication

task reveals effects of alcohol exposure during development

and that the effect is not specific to social stimuli

social recognition in both sexes the neural bases for these changes differs in the two sexes Female rats exposed to alco- hol during the postnatal period have been shown to have lower levels of estrogen than controls (3X), and this change may mediate the deficit in social recognition memory Simi- larly, males exposed to alcohol during the prenatal period show lower levels of testosterone (8.35) in adulthood and these lower levels may alter the function of the testosterone- dependent vasopressin fibers known to be involved in social recognition in males An interesting follow-up study would be

to examine the vasopressin system in males exposed to alco- hol during development

Social recognition of previously encountered juveniles by

adult rats treated with alcohol was impaired relative to control

rats Importantly, there were no differences among groups with

respect to time spent investigating the juvenile in the first ses-

sion or responding to a different juvenile in the second session

These latter findings suggest that the higher proportional scores

in the alcohol-exposed rats of both sexes after a 90.min interval

reflect a deficit in social recognition memory and not a differ-

ence in initial investigation of the juvenile rat or differences in

reactivity to the juvenile rat in the second session

In this and other (4) studies, females spend less time inves-

tigating the juvenile in the first session than males, suggesting

that this is a sexually dimorphic behavior Indeed, in females

social recognition appears to be mediated by estrogen Ovari-

ectomized females display decreased ability to form social

memories, but estradiol treatment in these animals reverses

this effect (18) In contrast, social recognition in males is likely

to be influenced by androgens and vasopressin Both periph-

eral and central injections of vasopressin enhance social rec-

ognition in males (9,lO) The interaction between androgens

and vasopressin is such that castration does not reduce inves-

tigations during the second exposure period (27) but vaso-

pressin antagonists no longer have any effect on the memory

for the juvenile rat (5) The vasopressinergic neurons originat-

ing in the bed nucleus of the stria terminalis projecting to the

lateral septum appear to mediate social recognition in males

and not in females (5)

The model utilizing intubations of alcohol during the early postnatal period worked well The mortality was low and there were no weight differences among the groups These findings are similar to those of others (28) Serbus et al (28) did not find any weight differences among their groups even though they did not use a second supplementary intubation 01 milk in the alcohol group However, they used a different strain of rat and lower levels of alcohol exposure than the cur- rent study The advantages of the use of the intubation proce- dure rather than artificial rearing to administer alcohol during the early postnatal period is that the pups still have both olfac- tory and tactile contact with the dam and siblings and feed mostly on the dam’s milk rather than a synthetic formula The contact with the dam and sibling is particularly important if one is interested in social behaviors The main disadvantage

of the intubation procedure is that the pups are handled dur- ing a period when handling has been shown to alter a number

of behaviors [see, e.g., (1 l)] However the intubated control group controls for these handling effects and care is taken to ensure that the animals have less than 2 min of handling per intuhation It should also be noted that altered pup-dam in- teractions may occur due to the changed behavior in the alco- hol-exposed pups and this may contribute to the differences in social behavior

In conclusion two forms of social behavior-social recogni- tion of juveniles and responsiveness to social communication- have been shown to be altered by alcohol exposure during the early postnatal period The alcohol-induced alterations are sex- ually dimorphic in one instance and the changes in social recog- nition in the two sexes quite possibly have different neural and hormonal bases Given the sexually dimorphic nature of social hchavior in general it may be prudent to investigate alcohol- induced alterations in social behavior in the two sexes scpa- rately Nevertheless these present data contribute to the grow- ing body of literature suggesting that alcohol exposure during development has severe and varied effects on social behavior

Because of the above findings, it is possible that whereas

alcohol exposure during development produces deficits in

We thank Frank Beylotte and Rebecca O’Neill for their technical assistance This research was supported by a Venture Fund Grant from the University of South Carolina

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