Change request default database in laravel 5.1

I make Request to Validate requested values from controller action by this way:

namespace App\Http\Requests;
use App\Http\Requests\Request;
class AccountsRequest extends Request {

    /**
     * Determine if the user is authorized to make this request.
     *
     * @return bool
     */
    public function authorize() {
        return TRUE;
    }

    public function rules() {
        return [
            'email' => 'email|required|max:255|unique:accounts',
            'password' => 'min:6|required'
        ];
    }
}

All is fine if I'm using the default database, but for this Validation I need to check the tables in other database. In config I have two databases:

'connections' => [

    'sqlite' => [
        'driver'   => 'sqlite',
        'database' => database_path('database.sqlite'),
        'prefix'   => '',
    ],

    'mysql' => [
        'driver'    => 'mysql',
        'host'      => env('DB_HOST', 'localhost'),
        'database'  => env('DB_DATABASE', 'sait'),
        'username'  => env('DB_USERNAME', 'root'),
        'password'  => env('DB_PASSWORD', ''),
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
        'strict'    => false,
    ],
    'mysql2' => [
        'driver'    => 'mysql',
        'host'      => env('DB_HOST', 'localhost'),
        'database'  => env('DB_DATABASE', 'account'),
        'username'  => env('DB_USERNAME', 'root'),
        'password'  => env('DB_PASSWORD', ''),
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
        'strict'    => false,
    ],

When I call the Validation, it is checking by "unique" rule in my default database so I need to change it, but I cannot found anywhere how to do this.

via Chebli Mohamed