Play fighting in androgen-insensitivetfm rats: Evidence that androgen receptors are necessary for the development of adult playful attack and defense

Masculinization of the male brain may in part be dependent on the effects of androgens on androgen receptors.

“masculinization of the male brain may in part be dependent on the effects of androgens on androgen receptors (Auger, Tetel, & McCarthy, 2000;Bakker, Honda, Harada, & Balthazart, 2002;Meaney & McEwen, 1986;Morris, Jordan, Dugger, & Breedlove, 2005).”

• cites Auger, Tetel, & McCarthy, 2000 sourceNot checked — no full text of the source
• cites Bakker, Honda, Harada, & Balthazart, 2002 sourcePartly supported

  The introduction (page unavailable) says testicular testosterone causes masculinization of the brain, supporting the androgen component of the claim. But it says many masculinizing effects are mediated by estradiol produced from testosterone, and the discussion’s mention of androgen-receptor-mutant animals concerns defeminization, not androgen-receptor-mediated masculinization. The proposed receptor mechanism is therefore not supported by this copy. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites Meaney & McEwen, 1986 sourceNot checked — no full text of the source

WT males defended against a playful attack at significantly higher levels as adults than as juveniles.

“WT males defended against a playful attack at significantly higher levels as adults than as juveniles F(1, 9) ¼ 6.92, p < .05.”

There was a significant main effect of time for the overall probability of playful defense.

“There was, however, a significant difference for the main effect of time F(1, 27) ¼ 4.60, p < .05.”

In adulthood, WT females used partial rotation significantly more than either male group.

“In adulthood the use of this tactic increased in females and decreased in WT males; thus in adulthood the WT females used this tactic significantly more than either male group F(2, 27) ¼ 50.37, p < .0001.”

As adults, only tfm males used complete rotation significantly more often than other groups.

“As adults, however, only the tfm males used this defensive tactic significantly more often F(2, 27) ¼ 4.18, p < .05.”

tfm males did not significantly decrease their number of playful attacks with age.

“Both male F(1, 9) ¼ 12.03, p < .01 and female F(1, 9) ¼ 28.53, p < .001WT animals showed a significant reduction in the number of playful attacks with age, in contrast to the tfm animals which did not significantly decrease their number of playful attacks with age F(1, 9) ¼ 1.99, p > .05(See Fig. 2A).”

As juveniles, females and tfm males used complete rotation as a defense against playful attack more frequently than did WT males.

“Post hoc analysis for each time point showed that, as juveniles, females and tfm males used the strategy of complete rotation as a defense against playful attack more frequently than did WT males F(2, 27) ¼ 6.69, p < .01.”

As juveniles, tfm males used the tactics of upright defense and evasion at the same frequency as WT males and females.

“The tfm males used the tactics of upright defense and evasion, at the same frequency as the WT males and females.”

Neither WT nor tfm male groups showed a reduction in the use of complete rotation during development.

“In contrast, neither of the male groups showed a reduction in the use of this defense strategy during development (WT: F(1, 9) ¼ 1.08, p > .05;tfm: F(1, 9) ¼ .11,p > .05).”

There was a significant group by time interaction for the probability of using a complete rotation as a playful defense.

“There was a significant group by time interaction F(2, 27) ¼ 3.64, p < .05for the probability of using a complete rotation as a playful defense.”

As juveniles, there were no significant group differences in the likelihood of using the upright defense.

“Post hoc analysis revealed that as juveniles there were no significant group differences F(2, 27) ¼ 1.88, p > .05 in the likelihood of using the upright defense.”

Both WT and tfm males significantly increased their use of the upright defense during development.

“While females did not show a significant change over time in the use of this tactic F(1, 9) ¼ 2.84, p > .05,both the WT F(1, 9) ¼ 60.02, p < .0001and tfm males F(1, 9) ¼ 5.33, p < .05significantly increased their use of the upright defense during development.”

WT females showed a significant reduction in the use of complete rotations with time.

“With time WT females showed a significant reduction in the use of complete rotations F(1, 9) ¼ 16.70, p < .01.”

There were no significant differences in attack frequency between any of the groups in adulthood.

“There were no significant differences in attack frequency between any of the groups in adulthood [F(2, 27) ¼ 1.48, p > .05].”

WT female rats showed a significant reduction in the number of playful attacks with age.

“Both male F(1, 9) ¼ 12.03, p < .01 and female F(1, 9) ¼ 28.53, p < .001WT animals showed a significant reduction in the number of playful attacks with age, in contrast to the tfm animals which did not significantly decrease their number of playful attacks with age F(1, 9) ¼ 1.99, p > .05(See Fig. 2A).”

Females did not show a significant change over time in the use of upright defense.

“While females did not show a significant change over time in the use of this tactic F(1, 9) ¼ 2.84, p > .05,both the WT F(1, 9) ¼ 60.02, p < .0001and tfm males F(1, 9) ¼ 5.33, p < .05significantly increased their use of the upright defense during development.”

As juveniles, tfm males played as frequently as WT males.

“As juveniles, tfm males played as frequently as WT males, but surprisingly, both groups of males played less frequently than WT females.”

• Also stated in: § Play in the Juvenile Phase · plain

  “Irrespective of whether the females play more than the males, in the strain used in the present study, the core finding is that the tfm males engage in play fighting at frequencies similar to WT males.”

As juveniles, female rats attacked at a higher frequency than did either WT or tfm males.

“Post hoc analysis for each time point showed that, as juveniles, females [F(2, 27) ¼ 12.53, p < .0001]attacked at a higher frequency than did either WT or tfm males.”

There was a significant group by time interaction for the use of an upright defense.

“There was a significant group by time interaction for the use of an upright defense F(2, 27) ¼ 16.15, p < .0001.”

There were no significant differences in playful defense over time for either WT females or tfm males.

“There were no significant differences in playful defense over time for either the WT female or tfm males.”

All three groups were equally likely to defend themselves against a playful attack.

“As all three groups were equally likely to defend themselves against a playful attack, the differences in frequency of play fighting were due to differences in the frequency of launching playful attacks.”

As juveniles, tfm males were significantly less likely to use partial rotation than were WT males or females.

“As juveniles tfm males were significantly less likely to use this tactic of playful defense than were WT males or females F(2, 27) ¼ 6.63, p < .01.”

There was a significant group by time interaction for the overall frequency of playful attack.

“There was a significant group by time interaction F(2, 27) ¼ 8.57, p < .01 for the overall frequency of playful attack.”

WT females showed a significant increase in the use of partial rotations with time.

“WT females showed a significant increase in the use of this tactic with time F(1, 9) ¼ 20.34, p < .01.”

As adults, WT males used the upright defense significantly more than either WT females or tfm males.

“As adult, however, the WT males used this tactic significantly more than either the WT females or tfm males F(2, 27) ¼ 24.72, p < .0001.”

There was a significant group by time interaction for the use of partial rotations as a playful defense.

“There was a significant group by time interaction for the use of partial rotations as a playful defense F(2, 27) ¼ 48.64, p < .0001(Fig. 3B).”

Both groups of males showed a significant reduction in the use of partial rotations during development.

“In contrast, for both groups of males there was a significant reduction in the use of this tactic during development (WT: F(1, 9) ¼ 111.26, p < .0001;tfm: F(1, 9) ¼ 18.62, p < .01).”

WT males used complete rotation significantly less than tfm males at both ages.

“In WT males, while the use of complete rotations did not decrease with age they used this tactic of defense significantly less than the tfm males at both ages.”

WT male rats showed a significant reduction in the number of playful attacks with age.

“Both male F(1, 9) ¼ 12.03, p < .01 and female F(1, 9) ¼ 28.53, p < .001WT animals showed a significant reduction in the number of playful attacks with age, in contrast to the tfm animals which did not significantly decrease their number of playful attacks with age F(1, 9) ¼ 1.99, p > .05(See Fig. 2A).”

tfm males used the upright tactic less often than WT males.

“but the upright tactic less often than the WT males.”

Adult tfm males showed no change in the partial rotation tactic.

“but no change in either the partial or complete rotation tactics.”

Like WT males, adult tfm males showed an increased use of the upright tactic.

“Like the WT males, the adult tfm males showed an increased use of the upright tactic”

WT males showed no change in the complete rotation tactic.

“and no change in the complete rotation tactic.”

tfm males used the partial rotation tactic as often as WT males.

“used the partial rotation tactic as often”

WT females showed no change in the use of the upright tactic.

“The WT females, in contrast, showed no change in the use of the upright tactic”

tfm males continued to launch playful attacks at the same frequency as when they were juveniles.

“as the tfm males continued to launch playful attacks at the same frequency as when they were juveniles.”

WT females showed an increase in the partial rotation tactic.

“an increase in the partial rotation tactic”

tfm males were like WT females with regard to likelihood of defending themselves.

“The tfm males were like the WT females with regard to likelihood of defending themselves”

• Also stated in: § Age-Related Changes in Play Fighting · plain

  “defended themselves with the same likelihood of females”

WT females showed a decrease in the complete rotation tactic.

“and a decrease in the complete rotation tactic.”

tfm males initiated more playful attacks than either WT males or females.

“The tfm males also initiated more playful attacks than either WT males or females”

• Also stated in: § Reconsideration of the Mechanisms for Masculinization and Defeminization · plain

  “as adults, tfm males launch more playful attacks”

Adult tfm males showed no change in the complete rotation tactic.

“but no change in either the partial or complete rotation tactics.”

WT males showed an increase in upright defense.

“WT males showed an increase in upright defense”

tfm males used the complete rotation tactic more often than WT animals of either sex.

“used the complete rotation tactic more often than the WT animals of either sex”

• Also stated in: § Reconsideration of the Mechanisms for Masculinization and Defeminization · plain

  “retain the use of the complete rotation defense tactic at a relatively high frequency”

There was an equal decline in the frequency of launching playful attacks by WT males and females.

“there was an equal decline in the frequency of launching playful attacks by WT males and females”

tfm males were like neither WT males nor females with regard to launching playful attacks.

“but like neither the WT males or females with regard to launching playful attacks”

WT males showed a decrease in the partial rotation tactic.

“a decrease in the partial rotation tactic”

WT males were more likely to defend themselves as adults.

“WT males were more likely to defend themselves as adults.”

In male rats, the use of complete rotations in response to playful attack decreases with the onset of puberty.

“With regard to playful defense it has been shown that while the probability of defense against a playful attack does not change with age in males (Pellis & Pellis, 1990;Pellis et al., 1997), the use of complete rotations, in response to playful attack, decreases with the onset of puberty (Pellis & Pellis, 1990, 1991).”

• cites Pellis & Pellis, 1990, 1991Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

tfm males can exhibit male sexual behavior as adults.

“It has been demonstrated that tfm males can exhibit male sexual behavior as adults (Olsen, 1979b;Shapiro, Levine, & Adler, 1980).”

• cites Olsen, 1979b sourceNot checked — no full text of the source
• cites Shapiro, Levine, & Adler, 1980 sourceNot checked — no full text of the source

The tfm mutation in the rat is a consequence of a point mutation in the androgen receptor gene corresponding to the steroid-binding domain, resulting in largely nonfunctional androgen receptors.

“In the rat (Stanley, Gumbreck, Allison, & Easley, 1973), the tfm is a consequence of a point mutation in the androgen receptor gene corresponding to the steroid-binding domain (Yarbrough et al., 1990) resulting in largely nonfunctional androgen receptors.”

• cites Stanley, Gumbreck, Allison, & Easley, 1973 sourceNot checked — no full text of the source
• cites Yarbrough et al., 1990 sourceNot checked — no full text of the source

Masculinization of the rodent CNS, in contrast to the periphery, is accomplished primarily by the aromatization of testosterone to estrogen.

“Given that the masculinization of the rodent CNS, in contrast to the periphery, is accomplished primarily by the aromatization of testosterone to estrogen (Olsen, 1992, McCarthy, 1994), it is thought that the CNS of the tfm male is largely masculinized and defeminized via this mechanism.”

• cites Olsen, 1992 sourceNot checked — no full text of the source
• cites McCarthy, 1994 sourceNot checked — no full text of the source

Castration during the neonatal period prior to postnatal day 10 in both tfm and WT males, in contrast to castration after postnatal day 10, is necessary to induce lordosis with estrogen treatment in adulthood.

“In addition, it has been shown that castration during the neonatal period prior to postnatal day 10 (Olsen, 1979a), in both the tfm and WT males, in contrast to castration after postnatal day 10 (Olsen & Whalen, 1981), is necessary to induce lordosis with estrogen treatment in adulthood.”

• cites Olsen, 1979a sourceNot checked — no full text of the source
• cites Olsen & Whalen, 1981 sourceNot checked — no full text of the source

Male rats castrated as neonates play at a lower frequency than intact males.

“Males castrated as neonates play at a lower frequency than do intact males (Beatty, Dodge, Traylor, & Meaney, 1981;Meaney, 1988;Meaney, Stewart, Poulin, & McEwen, 1983).”

• cites Beatty, Dodge, Traylor, & Meaney, 1981 sourceNot checked — no full text of the source
• cites Meaney, 1988 sourceNot checked — no full text of the source
• cites Meaney, Stewart, Poulin, & McEwen, 1983 sourceNot checked — no full text of the source

In Long Evans male rats, the higher frequency of play fighting depends on the presence of testicular hormones during the perinatal period.

“In addition, it has been shown that, in Long Evans male rats, the higher frequency of play fighting depends on the presence of testicular hormones during the perinatal period.”

• cites Beatty, Dodge, Traylor, & Meaney, 1981 sourceNot checked — no full text of the source
• cites Meaney, 1988 sourceNot checked — no full text of the source
• cites Meaney, Stewart, Poulin, & McEwen, 1983 sourceNot checked — no full text of the source

The reversed sex difference is more likely due to differences in the genetic profile of the strain used.

“More likely, this is due to the differences in the genetic profile of the strain used (Pellis et al., 1997;Reinhart et al., 2004).”

• cites Pellis et al., 1997 sourceNot checked — no full text of the source
• cites Reinhart et al., 2004 sourceNot checked — no full text of the source

The present findings are not consistent with previous findings where tfm males were found to have a female-typical pattern of play frequency.

“When viewed in this manner, the present findings are not consistent with previous findings where tfm males were found to have a female-typical pattern of play frequency (Meaney et al., 1983).”

• cites Meaney et al., 1983 sourceNot checked — no full text of the source

The results of the present study, using dyads, suggest that when tfm males are given the opportunity, they will play at levels comparable to WT males.

“The results of the present study, using dyads, suggest that when tfm males are given the opportunity, they will play at levels comparable to WT males.”

Estrogenic mechanisms are sufficient to generate male-typical levels of play fighting.

“This suggests that estrogenic mechanisms are sufficient to generate maletypical levels of play fighting.”

The sex difference in the frequency of play (females playing more than males) is contrary to that typically reported in many other studies.

“With regard to the sex difference in the frequency of play, this finding is contrary to that typically reported in many other studies (Pellis, 2002;Pellis et al., 1997;Thor & Holloway, 1986).”

• cites Pellis, 2002 sourceNot checked — no full text of the source
• cites Pellis et al., 1997 sourceNot checked — no full text of the source
• cites Thor & Holloway, 1986 sourceNot checked — no full text of the source

It is unlikely that the procedures used in the present experiment account for the reversed sex difference.

“Given that the testing paradigm we used is the same as that which has been used to consistently show sex differences in the frequency of play fighting in Long Evans hooded rats (e.g., Pellis & Pellis, 1990;Pellis et al., 1994), it is unlikely that the procedures used in the present experiment account for the reversed sex difference.”

• cites Pellis & Pellis, 1990 sourceNot checked — no full text of the source
• cites Pellis et al., 1994 sourceNot checked — no full text of the source

Previous analysis found that tfm males exhibit lower levels of play fighting than control males as juveniles.

“Previous analysis of the play behavior of tfm males found that they exhibit lower levels of play fighting than control males as juveniles (Meaney et al., 1983;Meaney, 1988).”

• cites Meaney et al., 1983 sourceNot checked — no full text of the source
• cites Meaney, 1988 sourceNot checked — no full text of the source

As juveniles, tfm males' use of complete rotation was more like WT females than WT males.

“In contrast, the tfm males used the complete rotation tactic more often than the WT males, and so were more like WT females.”

The differences in frequency of play fighting were due to differences in the frequency of launching playful attacks.

“As all three groups were equally likely to defend themselves against a playful attack, the differences in frequency of play fighting were due to differences in the frequency of launching playful attacks.”

As juveniles, tfm males show neither a clear male nor female-typical pattern of playful defense.

“With regard to the style of play used, as reflected in their use of different tactics of playful defense, tfm males, as juveniles, show neither a clear male or female-typical pattern of playful defense.”

In the Meaney et al. (1983) study, it is not possible to ascertain whether the tfm males were excluded from play bouts because the other group members preferred nontfm partners.

“Also, given that in the Meaney et al. (1983) study, the rats were observed when they were in groups of six, it is not possible to ascertain whether the tfm males were excluded from play bouts because the other group members preferred nontfm partners (see Pellis, Pellis, & McKenna, 1993).”

• cites Pellis, Pellis, & McKenna, 1993 sourceNot checked — no full text of the source

Male-typical levels of play fighting during the juvenile period are dependent on androgen receptor-mediated effects of androgens on the CNS.

“This suggests that male-typical levels of play fighting during the juvenile period are dependent on androgen receptor-mediated effects of androgens on the CNS.”

Spontaneous levels of play are much lower than the levels of play exhibited following some period of social isolation.

“It has been shown, however, that spontaneous levels of play are much lower than the levels of play that are exhibited following some period of social isolation (Panksepp, 1981;Pellis et al., 1997), and in the present study, rats were observed following 24 hr of social isolation.”

• cites Panksepp, 1981 sourceNot checked — no full text of the source
• cites Pellis et al., 1997 sourceNot checked — no full text of the source

The tfm male provides a model by which to differentiate the effects of male body morphology from male neural organization when comparing differences between males and females.

“The tfm male provides a model by which to differentiate the effects of male body morphology from male neural organization when comparing differences between males and females (Field, Watson, Whishaw, & Pellis, 2005;Field, Martens, Watson, & Pellis, 2005).”

• cites Field, Watson, Whishaw, & Pellis, 2005 sourceNot checked — no full text of the source
• cites Field, Martens, Watson, & Pellis, 2005 sourceNot checked — no full text of the source

These combined changes left the adult tfm males with a profile that was atypical of either sex.

“In sum, these combined changes left the adult tfm males with a profile that was atypical of either sex.”

Neither the play profile present in the juvenile phase nor the age-related changes leading to the adult pattern reveal a simple case of the tfm males either being male-like or female-like.

“Therefore, neither the play profile present in the juvenile phase or the age-related changes leading to the adult pattern, reveal a simple case of the tfm males either being male-like or female-like.”

Changing the strain of the play partner can have marked effects on strain-typical patterns of play fighting.

“changing the strain of the play partner can have marked effects on strain-typical patterns of play fighting (Reinhart, Metz, McIntyre, & Pellis, 2005).”

• cites Reinhart, Metz, McIntyre, & Pellis, 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

For some features of play fighting, nonhormonal factors may be important in generating developmental differences between the sexes.

“Finally, the present findings indicate that for some features of play fighting, nonhormonal factors may be important in generating developmental differences between the sexes.”

To produce the fully male-typical pattern of play requires both masculinization and defeminization.

“to produce the fully male-typical pattern of play requires both masculinization and defeminization (Pellis, 2002).”

• cites Pellis, 2002 sourceNot checked — no full text of the source

These findings suggest that there may be important epigenetic interactions in shaping some sex-differentiated patterns of behavior.

“These findings suggest that there may be important epigenetic interactions in shaping some sex-differentiated patterns of behavior.”

The aromatization of androgens to estrogens and subsequent estrogen receptor activation are sufficient to make some features of play fighting male typical.

“The present study shows that the aromatization of androgens to estrogens and subsequent estrogen receptor activation are sufficient to make some features of play fighting male typical”

tfm males retain a more juvenile-typical pattern of play as adults.

“that is, they retain a more juvenile-typical pattern of play as adults.”

Recent results testing the spatial abilities of tfm males in the Morris water maze show that tfm males perform at a level between WT males and females.

“Recent results testing the spatial abilities of tfm males in the Morris water maze, showing that tfm males perform at a level between WT males and females supports this conclusion (Jones & Watson, 2005).”

• cites Jones & Watson, 2005 sourceNot checked — no full text of the source