Yes, most of the studies of D-Cycloserine have been looking at using the drug as an adjunct to exposure therapy, but there have also been several studies that suggest the drug alone has a positive effect on social behavior, without attendant therapy.
looked at socially withdrawn autistic children:
D-cycloserine seems to improve social and communication skills in autistic children
NEW YORK, USA: D-cycloserine, a drug that has shown to reduce symptoms in schizophrenics, appears significantly to improve social and communication skills in children with autism, according to the results of a small pilot study published in the November 2004 edition of the American Journal of Psychiatry.
found that mice given D-cycloserine exhibited ehanced "social investigation":
Psychopharmacology (Berl). 1994 Nov;116(3):317-25.
D-cycloserine [DCS] enhances social behaviour in individually-housed mice in the resident-intruder test.
Resident mice given DCS (32.0-320.0 mg/kg PO, 60 min before testing) showed dose-dependent increases in social investigation, smaller increases in sexual behaviour and decreased aggressiveness. Defensive and flight behaviour were not affected. Intruder mice showed slight increases in sexual behaviour that were not dose-dependent, and small increases in social investigation.... Within the parameters of the resident-intruder situation, DCS exerts socio-sexual behaviour-enhancing effects which are dependent upon the role of the interactant, and which are mediated by an action upon multiple substrates. DCS may be regarded as another example of a sociotropic (approach-promoting) agent.
So it appears that D-Cycloserine may reduce the fear response, which when coupled with exposure therapy can help patients "unlearn" their fear reactions. But it also appears as though D-Cycloserine alone (without therapy) enhances pro-social behavior by dampening the fear/anxiety response. In fact, if it didn't, it would be of little use as an adjunct to exposure therapy.
A few weeks ago there was a poster on psychobabble
who had tried the drug and claimed that even without therapy, it had worked as well to counter his social phobia as "the old Nardil" had, and without side effects. Unfortunately, he hasn't posted any recent updates.
Very intriguing stuff....