forty-eight hours later , after an acute microinjection of histamine ( 1 microgram ) , 3-methyl-histamine ( 1 microgram ) or saline ( 1 microliter ) , the following behavioral parameters were measured by an observer in an open-field : locomotor , rearing , sniffing , grooming , social sniffing and holding activities .
C0019588
histamine
C0025779
methyl-histamine