Differential effects of flurothyl- and electro-convulsive shock on sexual maturation and prolactin release in the rat

Summary The effects of single and repeated seizures on luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin secretion and on the onset of sexual maturation in rats are described. In addition, the influence of convulsions generated electrically (electroconvulsive shock, ECS) and chemically (using flurothyl) are compared. Repeated flurothyl convulsions and ECS (one daily convulsion from age 24 days) significantly delay vaginal opening in female rats. The incidence of first ovulation at maturation is reduced to 20% compared with 70–100% for untreated groups. Body and adrenal weights in immature rats are not modified by flurothyl convulsions. Repeated ECS does not influence adrenal weight although somatic growth is inhibited. In an effort to clarify the mechanism of action of convulsions on puberty onset, we examined acute changes in LH, FSH and prolactin secretion and the surge response of LH/FSH to gonadal steroid priming. A single flurothyl convulsion potently inhibits prolactin secretion. In contrast, an ECS acutely stimulates prolactin release in male and female rats. Convulsive seizures do not consistently alter tonic gonadotropin output. However, both flurothyl convulsions and ECS attenuate estradiol benzoate/progesterone-induced LH and FSH surges in ovariectomized rats though this is apparently not mediated by dopamine/prolactin since bromocriptine treatment delays sexual maturation without preventing ovulation at first estrus. Similarly, bromocriptine does not disrupt LH/FSH surges induced by gonadal steroid treatment. One component in the neural response to convulsions may be hypothalamic endogenous opiate peptides since the ability of naloxone to influence LH and prolactin secretion is potentiated by repeated ECS. On the other hand, dopamine is clearly implicated in the flurothyl-induced inhibition of prolactin secretion, since haloperidol reverses this effect.