Directly - not possible.
Indirectly - 3 methods come to mind.
Method 1. Using the Oracle DCOM interface. See Oracle® COM Automation Feature Developer's Guide for details. (no examples from me - do not use Windows and Oracle together as server architecture)
Method 2. Using Oracle External Proc (EXTPROC) Interface. See Developing Applications with Multiple Programming Languages for details. See Re: write to syslog from pl/sql for an example.
Please always provide detailed information about DB version and OS it's installed.
I guess you're with DB on Windows -you can have a stored procedure that is build in .NET so you can what is to be called from out there.
More details here :