RELATIONSHIPS AMONG GNRH, SUBSTANCE-P, PROSTAGLANDINS, SEX STEROIDS AND AROMATASE-ACTIVITY IN THE BRAIN OF THE MALE LIZARD PODARCIS-SICULA-SICULA DURING REPRODUCTION

The release of PGF(2 alpha) and PGE(2), progesterone, androgens and oe stradiol in vitro, and the aromatase activity in the brain of the male lizard Podarcis sicula sicula during three different phases of the re productive period were evaluated. In addition, the effects of salmon G nRH, substance P, salmon GnRH antagonist, substance P antagonist, PGF( 2 alpha), PGE(2) and acetylsalicylic acid on the release of prostaglan dins and sex steroids and on aromatase activity in the brain were eval uated during the same three phases. PGF(2 alpha), oestradiol and aroma tase activity were higher during the refractory phase, androgens durin g the fighting phase, and progesterone during the mating phase, while PGE, was lower during the refractory phase. Treatment with salmon GnRH increased PGF(2 alpha), oestradiol and aromatase activity, but decrea sed the amount of androgens released. Substance P decreased PGF(2 alph a), oestradiol and aromatase activity, but increased the amount of and rogens released. PGF(2 alpha), increased oestradiol and aromatase acti vity, but decreased the amount of androgens released. Acetylsalicylic acid decreased PGF(2 alpha), oestradiol and aromatase activity, but in creased the amount of androgens released. These data suggest that salm on GnRH and substance P have different roles in reproductive processes , with opposite mechanisms, in the central nervous system of this male lizard: salmon GnRH seems to be involved in regulating the refractory phase, while substance P plays a role in regulating the fighting phas e.