Joomla - Trigger Plugin

        $article = new stdClass;
        $article->text = $text;

        $output = JResponse::getBody();

        // add more to parameters if needed
        $params = new JObject;

        // Note JDispatcher is deprecated in favour of JEventDispatcher in Joomla 3.x however still works.
        JPluginHelper::importPlugin('content');
        $dispatcher = JEventDispatcher::getInstance();
        $dispatcher->trigger('onContentPrepare', array('com_custom', , &$params, 0));