select * from V$NLS_PARAMETERS where (parameter = 'NLS_CHARACTERSET');

NLS_CHARACTERSET	CL8MSWIN1251

alter PROCEDURE [dbo].[test]
AS
BEGIN
  DECLARE @region AS nvarchar(128)

  DECLARE [lcAddress] CURSOR FOR
    SELECT t1.region
    FROM MISC..OMS.MARS#OSA_TOPIC t1
    WHERE (34630 = t1.id)

  OPEN [lcAddress]
  FETCH NEXT FROM [lcAddress] INTO @region, @region2
  CLOSE [lcAddress]
  DEALLOCATE [lcAddress]

  SELECT @region --текст не читаем

  DECLARE [lcAddress1] CURSOR FOR
    SELECT CAST(t1.region AS nvarchar(1000)) region
    FROM OPENQUERY(MISC, 'SELECT t1.region
    FROM OMS.MARS#OSA_TOPIC t1
    WHERE (34630 = t1.id)') t1

  OPEN [lcAddress1]
  FETCH NEXT FROM [lcAddress1] INTO @region
  CLOSE [lcAddress1]
  DEALLOCATE [lcAddress1]

  SELECT @region --текст не читаем

  SELECT @region = t1.region
  FROM MISC..OMS.MARS#OSA_TOPIC t1
  WHERE (34630 = t1.id)

  SELECT @region --текст не читаем
   
  --текст нормально читаем
  SELECT t1.region
  FROM MISC..OMS.MARS#OSA_TOPIC t1
  WHERE (34630 = t1.id)

  --текст нормально читаем
  SELECT t1.region
  FROM OPENQUERY(MISC, 'SELECT t1.region
  FROM OMS.MARS#OSA_TOPIC t1
  WHERE (34630 = t1.id)') t1
END
GO