[Abstract Title]. - Society for Neuroscience

Authors: T. SPITERI 1 , S. MUSATOV 2 , A. RIBEIRO 3 , S. OGAWA 4 , D. W. PFAFF 3 , *A.
AGMO 1 ;
1 Inst. Psykologi, Univ. Tromsoe, N-9037 Tromso, Norway; 2 Lab. of Mol. Neurosurg., Weill
Med. Col. of Cornell Univ., New York, 10021, NY; 3 Lab. of Neurobio. and Behavior, The
Rockefeller Univ., New York, 10021, NY; 4 Lab. of Behavioral Neuroendocrinology, Univ. of
Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
Abstract: Social recognition manifests itself in decreased investigation of a previously
encountered individual. There is evidence suggesting that oxytocin (OT) in the medial amygdala
regulates both social recognition and anxiety in rodents. OT action is mediated by OT receptors
and estrogens drive this receptor expression, especially through the ERα in various brain areas
including the amygdala. Studies of female mice, whose genes for either OT, ERα or ERβ had
been knocked out, showed that they were deficient in social recognition and they were less
anxious. These data suggest that ERα is implicated in these behaviors. However, the effects of a
selective reduction of ERα in the medial amygdala on social recognition and anxiety have not
been evaluated. This was made in the present experiment. The effects of silencing ERα in the
ventromedial nucleus of the hypothalamus (VMN) were also determined because this nucleus is
implicated in neural circuits regulating maternal behaviors. For these, the recognition of pups is
believed to be crucial. A shRNA encoded within an adeno-associated viral (AAV) vector
directed against the ERα receptor gene (or containing luciferase control), was infused bilaterally
into the medial posterodorsal amygdala (MePDA) or the VMN of female rats. About 3 weeks
later, the females were given an sc injection of EB followed by P. Starting 6 hr thereafter they
were repeatedly exposed to the same juvenile rat. After 4 exposures, a novel juvenile was
presented. Social interactions, including aggressive, were recorded. Anxiety-like behaviors were
evaluated in the light/dark choice test. Finally, aggression towards an adult intruder was
evaluated. An 80 % reduction of ERα expression in the MePDA eliminated social recognition.
There was no sign of habituation to the juvenile, and consequently no sign of dishabituation
when the familiar juvenile was replaced by a novel juvenile. No change in aggression towards
the juvenile was observed. Social recognition was unaffected after ERα knockdown in the VMN.
Females presented a normal habituation to the juvenile and a restoration of investigation when a
novel juvenile replaced the familiar. To the contrary, ERα knockdown in the VMN enhanced the
aggressiveness against the juvenile conspecific at the first exposure and at presentation of the
novel juvenile. The light/dark choice test as well as the resident-intruder test did not reveal any
significant effect after infusion of ERα AAV into the MePDA or into the VMN. In conclusion,
social recognition in female rats depends on the ERα in the MePDA. Moreover, aggression
against juveniles but not against adults could, at least partly, depend on the ERα in the VMN.
Disclosures: T. Spiteri, None; A. Agmo , None; S. Musatov, None; A. Ribeiro, None; S.
Ogawa, None; D.W. Pfaff, None.
Poster
297. Social Recognition and Partner Preference