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To detect stellar activity cycles and study the possible star-planetinteractions (SPI's), we have developed both HK$\alpha$ and SPI-HK$\alpha$projects since 1999 and 2012 respectively.  In this work, we present preliminary results of possible SPI's studying thechromospheric activity and look for possible correlations between stellaractivity and stellar/planetary parameters. We find that for stars with similarT$_{eff}$, stellar activity increases with the mass of the planet, similar toprevious works. However, stellar ages can also play a role and a larger stellarsample is needed to verify these trends. We also note that some of these starspresent a remarkably high level of chromospheric activity, even comparable withRSCvn or BY Dra active stars. In addition, we do not observe any correlationbetween stellar activity and semi-major axis.  We present the first long-term activity study of the star $\iota$ Horologii,a young solar-type star which hosts a non-transiting Jovian planet and presentsa high activity level. We analyze our own spectra, obtained between 2002 and2015, combined with public HARPS observations. We calculate the Ca II indexesderived from the 987 CASLEO and HARPS spectra and convert them to theMount-Wilson scale. We found a long-term activity cycle of $\sim$ 5 years whichfits the active sequence of Bohm-Vitense. The amplitude of this longer cycle isirregular, as was also observed for the shorter one. This fact could beattributed to an antisymmetric distribution of active regions on the stellarsurface.

A possible long-term activity cycle for {\iota} Horologii: First results from the HK{\alpha} & SPI-HK{\alpha} projects