Reversibility of dopamine receptor antagonist-induced hyperprolactinemia and associated histological changes in Tg RasH2 wild-type mice

Reproductive toxicology studies supporting the safety of molindone, a dopamine receptor antagonist

BACKGROUND

An extended-release molindone (a dopamine D₂ and serotonin antagonist) is currently being developed as a novel treatment for impulsive aggression (IA) in patients optimally treated for ADHD. Oral Good Laboratory Practice reproductive toxicology studies (fertility and early embryonic [FEE], prenatal/postnatal [PPN], embryo-fetal development [EFD]) were conducted with molindone HCl using International Conference on Harmonisation (ICH) S5(R2)-compliant protocols.

METHODS

In the FEE study, 0, 5, 15, or 30 mg kg^-1  day^-1 was administered to female (2 weeks premating through implantation) and male (4 weeks premating for 57 days) rats, and fertility parameters were evaluated. In the EFD studies, rats received 0, 5, 20, or 40 mg kg^-1 day^-1 on gestational days (GDs) 6-17; rabbits received 0, 5, 10, or 15 mg kg^-1 day^-1 on GDs 6-18. Ovarian/uterine and fetal parameters were evaluated at term. In the PPN study, F₀ rats received 0, 5, 20, or 40 mg kg^-1 day^-1 (GD6-LD21); behavior and reproduction were evaluated in F₁ offspring.

RESULTS

Parental hypoactivity and reduced body weight gain occurred in all studies. In the FEE, prolonged estrous cycles and delayed mating occurred at ≥15 mg kg^-1 day^-1 , without effects on fertility or embryonic development. No developmental toxicity occurred in F₁ fetuses. In F₁ pups, reduced preweaning growth was observed at 40 mg kg^-1 day^-1 , but there were no effects on postweaning growth, behavior, or reproduction.

CONCLUSIONS

Molindone was not developmentally toxic in rats or rabbits at 69X and 6X clinical exposures, confirming the reproductive safety of molindone. Changes in estrous cyclicity were related to species-specific pharmacological effects of molindone in rodents and are not considered relevant to human risk.

The mechanism of selfheal extract in treating hyperprolactinemia

OBJECTIVE

Selfheal has been used for many years in hyperprolactinemia induced galactorrhea, menstrual disorders, and dysgenesis with satisfactory curative effect. However, its mechanism is still unclear. This study intended to investigate the effect of selfheal extract on hyperprolactinemia in vivo and in vitro, in order to elucidate its mechanism of anti-hyperprolactinemia.

PATIENTS AND METHODS

Hyperprolactinemia rat model was established. High dose (28.8 g/(kg⋅d)), middle dose (14.4 g/ (kg⋅d)), and low dose (7.2 g/(kg⋅d)) of selfheal extract were used to treat the model to observe impact on serum estradiol (E2), progesterone (P), prolactin (PRL), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels. Three cell lines MMQ, GH3, and PC12 were applied to investigate selfheal extract effect on PRL secretion, dopamine D2 receptor, and dopamine transporter (DAT).

RESULTS

High and middle dose of selfheal extract significantly reduced PRL level in hyperprolactinemia rat compared with model group (P< 0.01). Compared with normal control, 5 mg/ml and 10 mg/ml selfheal extract obviously inhibited PRL secretion in MMQ cells that high expressed D2 receptor after 24 hours (P< 0.01), but did not affect PRL secretion in GH3 cells lack of D2 receptor. 8 mg/ml selfheal extract markedly suppressed D2 receptor and DAT expression in PC12 cells that strongly expressed D2 receptor and DAT (P< 0.01).

CONCLUSIONS

Selfheal extract treated hyperprolactinemia through dopamine D2 receptor with significant effect.