$(document).ready(function() {
    //hide the all of the element with class msg_body
    $(".msg_body").hide();
    //toggle the componenet with class msg_body
    $(".msg_head").click(function() {
        $(this).prev(".msg_body").slideToggle(400);
        if (this.src.indexOf("Content/Images/close.gif") > 0)
            this.src = "Content/Images/more.gif";
        else
            this.src = "Content/Images/close.gif";
    });
});