Photoperiodic and pineal influences on estrogen-stimulated behaviors in female Syrian hamsters.
Physiol Behav
; 54(1): 19-28, 1993 Jul.
Article
em En
| MEDLINE
| ID: mdl-8327603
ABSTRACT
Three experiments investigated the effects of short photoperiod exposure on the estrogenic facilitation of locomotor activity and lordosis. In Experiment 1, ovariectomized female hamsters were administered exogenous estrogen to stimulate locomotor activity in running wheels. Estrogen was effective in the long photoperiod group but did not stimulate running-wheel activity in the short photoperiod group. In Experiment 2, the role of the pineal gland in mediating photoperiodic influences on female hamster behavior was examined. Both estrogen-induced locomotor activity and estrogen+progesterone-stimulated lordosis behavior were significantly reduced in short photoperiod females. Both these photoperiodic effects were absent in pinealectomized hamsters. Sham-pinealectomized, short photoperiod females expressed behavioral deficits; pinealectomized hamsters in the short photoperiod did not. Experiment 3 investigated lordosis only and used hormone injections rather than silastic implants to administer estrogen. The photoperiodic and pineal effects observed in Experiment 2 were replicated in Experiment 3. Additionally, the suppression of lordosis responsiveness by short photoperiod exposure was estrogen dose dependent. Photoperiodic effects were present when 2 micrograms estradiol cypionate was used but absent when higher estrogen doses were used. These findings are discussed in the context of other results that suggested photoperiodic effects on hamster lordosis were pineal independent.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Glândula Pineal
/
Comportamento Sexual Animal
/
Ritmo Circadiano
/
Estrogênios
/
Luz
Limite:
Animals
Idioma:
En
Revista:
Physiol Behav
Ano de publicação:
1993
Tipo de documento:
Article