When was the American drama television series which Peter Horton played ole of Professor Gary Shepherd on aired 
Peter Horton:  He is perhaps best known for the role of Professor Gary Shepherd on the television series "Thirtysomething" which he played from 1987 until 1991. Thirtysomething: Thirtysomething (stylized as thirtysomething) is an American drama television series created by Ed Zwick and Marshall Herskovitz for ABC that aired from 1987 to 1991.
from 1987 to 1991