Electrons are more susceptible to energy losses in magnetic fields and photon fields than protons. Hence, photons at various wavelengths, including gamma rays, bring more readily information on high-energy electrons than on protons. Neutrinos provide a unique tracer for protons. Furthermore, at high energies the neutrino flux can considerably exceed the gamma-ray flux, as gamma rays above ~ 1 MeV are degraded by γ-γ interactions in compact high-intensity sources. Active galactic nuclei (AGN) with outputs > 1045 ergs s−1 and dimensions ~ 1014 cm would constitute such sources. If the AGN are powered by ultra-massive black holes, then these numerical conditions are satisfied, and at high energies the flux J ν > J γ. Berezinsky and Ginzburg have pointed out that the photon intensity around spinars is not sufficient to cause gamma-ray degradation. These authors have demonstrated that the measurement of neutrino flux, combined with the measurement (or upper limit) of gamma-ray flux would show whether the active galactic nuclei are powered by massive black holes or spinars. We estimate that gamma rays would be degraded at spinars, too, at energies > 1 GeV.