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Titolo:
Photoresponsive Fischer 344 rats are reproductively inhibited by melatoninand differ in 2-[I-125] iodomelatonin binding from nonphotoresponsive Sprague-Dawley rats
Autore:
Heideman, PD; Bierl, CK; Sylvester, CJ;
Indirizzi:
Coll William & Mary, Dept Biol, Williamsburg, VA 23187 USA Coll William & Mary Williamsburg VA USA 23187 Williamsburg, VA 23187 USA
Titolo Testata:
JOURNAL OF NEUROENDOCRINOLOGY
fascicolo: 3, volume: 13, anno: 2001,
pagine: 223 - 232
SICI:
0953-8194(200103)13:3<223:PF3RAR>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
HAMSTERS PHODOPUS-SUNGORUS; WHITE-FOOTED MICE; 2-IODOMELATONIN BINDING; SIBERIAN HAMSTERS; DEER MICE; PUBERTAL DEVELOPMENT; PEROMYSCUS-LEUCOPUS; SIGNAL TRANSDUCTION; SEXUAL-MATURATION; TROPICAL RODENT;
Keywords:
melatonin receptors; photoresponsiveness; physiological variation; seasonal breeding; paraventricular nucleus; reuniens nucleus;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Heideman, PD Coll William & Mary, Dept Biol, POB 8795, Williamsburg, VA 23187 USA Coll William & Mary POB 8795 Williamsburg VA USA 23187 87 USA
Citazione:
P.D. Heideman et al., "Photoresponsive Fischer 344 rats are reproductively inhibited by melatoninand differ in 2-[I-125] iodomelatonin binding from nonphotoresponsive Sprague-Dawley rats", J NEUROENDO, 13(3), 2001, pp. 223-232

Abstract

Many temperate-zone species use photoperiod as an environmental cue to regulate reproductive timing. Strains of laboratory rats differ in their responsiveness to photoperiod, with the Fischer 344 (F344) strain being the mostresponsive known. F344 rats and closely related strains that differ in photoresponsiveness may be useful models to study the mechanisms and genetic basis for photoresponsiveness. We tested two hypotheses: (i) that melatonin mediates photoresponsiveness in F344 rats, as is the case in all other mammals tested, and (ii) that the location, abundance, or affinity of melatoninreceptors, as estimated by the amount and location of binding of the radioligand 2-[I-125]- iodomelatonin (IMEL) in the brain, might cause variation in photoresponsiveness among rat strains. Melatonin injections 1 h before lights off in a stimulatory photoperiod (L14:D10) induced reproductive inhibition and reduced weight gain in a manner similar to short days of L8:D16, while injections of ethanolic saline vehicle did not. Interestingly, melatonin injections administered during an inhibitory photoperiod (L10:D14) caused greater inhibition of both reproduction and weight gain than short photoperiod alone. Pinealectomized F344 rats implanted subcutaneously with melatonin in a silastic capsule did not differ in testis size or body weight from controls with blank implants. The brains and pars tuberalis of the pituitary from photoresponsive F344 rats and nonphotoresponsive Harlan Sprague-Dawley (HSD) rats were processed for autoradiography using IMEL, We found significantly higher specific IMEL binding in the anterior and posterior regions of the paraventricular nucleus of the thalamus (PVNt) and reuniens nucleus of the thalamus of F344 rats than in the same areas in HSD rats. There were no differences between strains in specific IMEL binding in the medial PVNt, anteroventral and anterodorsal nucleus of the thalamus, suprachiasmatic nucleus, or the pars tuberalis. These results indicate that melatonin mediates photoresponsiveness in F344 rats. In addition, they provide support for the hypothesis that F344 rats may be photoresponsive due to differences from other strains in the location, density, or affinity of melatonin receptors.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/03/20 alle ore 23:51:28