Biomaterial Database

Effect of anterior hypothalamic area lesions on photoperiod-induced shifts in reproductive activity of the ewe. 1994

S M Hileman, and D E Kuehl, and G L Jackson

Department of Veterinary Biosciences, University of Illinois, Urbana 61801.

The areas of the brain involved in photoperiodic control of reproduction are not well defined. The objective of this study was to determine whether anterior hypothalamic area (AHA) lesions in the ewe affected the responses of the reproductive system to shifts in the length of the daily photoperiod and development of photorefractoriness to a constant short day photoperiod. Eleven intact ewes received bilateral radiofrequency lesions of the AHA (AHAX), and five received sham lesions (sham). The ewes then were placed in photochambers and exposed alternately to two approximately 90-day periods of long [16 h of light, 8 h of darkness (16L:8D)] and short (10L:14D) days and then to 10L:14D for an additional 165 days. Blood samples were collected twice weekly to monitor plasma profiles of progesterone, PRL, and total T4, and during the second 16L:8D photoperiod, hourly for one 24-h period to assess melatonin release. Lesions increased (P < 0.001) the interval between the start of long days and cessation of estrous cycles during both long day periods, but did not affect the interval between the start of short days and the onset of estrous cycles for either the first (P = 0.08) or second (P > 0.10) short day period. Consequently, the durations of both anestrous periods were shorter (P < 0.001) for AHAX than for sham ewes. AHA lesions did not affect (P > 0.10) diurnal patterns of melatonin release. No effects (P > 0.10) of lesions were evident on plasma patterns of PRL or total T4 for any short or long day photoperiod. Development of photorefractoriness to constant short days either did not occur or was markedly delayed in five of nine AHAX (P < 0.01) ewes, whereas the other four AHAX ewes became refractory at a time similar (P > 0.10) to that in sham ewes. Responses to inhibitory long day photoperiods and constant short days were highly (P < 0.05) correlated (r = 0.74) and appeared dependent upon the extent of the AHA lesion. These results suggest that AHA lesions disrupt neuronal pathways mediating the effects of shifts in photoperiod on reproductive activity and development of photorefractoriness to constant short days. Our results suggest that the effects of AHA lesions are confined to the termination of reproductive activity, and that different neural pathways participate in photostimulation vs. photosuppression or photorefractoriness.

UI	MeSH Term	Description	Entries
D007027	Hypothalamic Diseases	Neoplastic, inflammatory, infectious, and other diseases of the hypothalamus. Clinical manifestations include appetite disorders; AUTONOMIC NERVOUS SYSTEM DISEASES; SLEEP DISORDERS; behavioral symptoms related to dysfunction of the LIMBIC SYSTEM; and neuroendocrine disorders.	Froehlich's Syndrome,Hypothalamic-Neurohypophyseal Disorders,Pituitary Diencephalic Syndrome,Hypothalamic Dysfunction Syndromes,Hypothalamic Dysinhibition Syndrome,Hypothalamic Overactivity Syndrome,Hypothalamic Pseudopuberty,Hypothalamic-Adenohypophyseal Disorders,Diencephalic Syndrome, Pituitary,Diencephalic Syndromes, Pituitary,Disease, Hypothalamic,Diseases, Hypothalamic,Disorder, Hypothalamic-Adenohypophyseal,Disorder, Hypothalamic-Neurohypophyseal,Disorders, Hypothalamic-Adenohypophyseal,Disorders, Hypothalamic-Neurohypophyseal,Dysfunction Syndrome, Hypothalamic,Dysfunction Syndromes, Hypothalamic,Dysinhibition Syndrome, Hypothalamic,Dysinhibition Syndromes, Hypothalamic,Froehlich Syndrome,Froehlichs Syndrome,Hypothalamic Adenohypophyseal Disorders,Hypothalamic Disease,Hypothalamic Dysfunction Syndrome,Hypothalamic Dysinhibition Syndromes,Hypothalamic Neurohypophyseal Disorders,Hypothalamic Overactivity Syndromes,Hypothalamic Pseudopuberties,Hypothalamic-Adenohypophyseal Disorder,Hypothalamic-Neurohypophyseal Disorder,Overactivity Syndrome, Hypothalamic,Overactivity Syndromes, Hypothalamic,Pituitary Diencephalic Syndromes,Pseudopuberties, Hypothalamic,Pseudopuberty, Hypothalamic,Syndrome, Froehlich's,Syndrome, Hypothalamic Dysfunction,Syndrome, Hypothalamic Dysinhibition,Syndrome, Hypothalamic Overactivity,Syndromes, Hypothalamic Dysfunction,Syndromes, Hypothalamic Dysinhibition,Syndromes, Hypothalamic Overactivity,Syndromes, Pituitary Diencephalic
D007032	Hypothalamus, Anterior	The front portion of the HYPOTHALAMUS separated into the preoptic region and the supraoptic region. The preoptic region is made up of the periventricular GRAY MATTER of the rostral portion of the THIRD VENTRICLE and contains the preoptic ventricular nucleus and the medial preoptic nucleus. The supraoptic region contains the PARAVENTRICULAR HYPOTHALAMIC NUCLEUS, the SUPRAOPTIC NUCLEUS, the ANTERIOR HYPOTHALAMIC NUCLEUS, and the SUPRACHIASMATIC NUCLEUS.	Hypothalamus, Supraoptic,Anterior Hypothalamic Commissure,Anterior Hypothalamic Decussation of Ganser,Anteroventral Periventricular Nucleus,Anterior Hypothalamic Commissures,Anterior Hypothalamus,Commissure, Anterior Hypothalamic,Commissures, Anterior Hypothalamic,Hypothalamic Commissure, Anterior,Hypothalamic Commissures, Anterior,Nucleus, Anteroventral Periventricular,Periventricular Nucleus, Anteroventral,Supraoptic Hypothalamus
D008550	Melatonin	A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.
D011374	Progesterone	The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.	Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D011388	Prolactin	A lactogenic hormone secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). It is a polypeptide of approximately 23 kD. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Prolactin receptors are present in the mammary gland, hypothalamus, liver, ovary, testis, and prostate.	Lactogenic Hormone, Pituitary,Mammotropic Hormone, Pituitary,Mammotropin,PRL (Prolactin),Hormone, Pituitary Lactogenic,Hormone, Pituitary Mammotropic,Pituitary Lactogenic Hormone,Pituitary Mammotropic Hormone
D012098	Reproduction	The total process by which organisms produce offspring. (Stedman, 25th ed)	Human Reproductive Index,Human Reproductive Indexes,Reproductive Period,Human Reproductive Indices,Index, Human Reproductive,Indexes, Human Reproductive,Indices, Human Reproductive,Period, Reproductive,Periods, Reproductive,Reproductive Index, Human,Reproductive Indices, Human,Reproductive Periods
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012756	Sheep	Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.	Ovis,Sheep, Dall,Dall Sheep,Ovis dalli
D013974	Thyroxine	The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (MONOIODOTYROSINE) and the coupling of iodotyrosines (DIIODOTYROSINE) in the THYROGLOBULIN. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form TRIIODOTHYRONINE which exerts a broad spectrum of stimulatory effects on cell metabolism.	L-Thyroxine,Levothyroxine,T4 Thyroid Hormone,3,5,3',5'-Tetraiodothyronine,Berlthyrox,Dexnon,Eferox,Eltroxin,Eltroxine,Euthyrox,Eutirox,L-3,5,3',5'-Tetraiodothyronine,L-Thyrox,L-Thyroxin Henning,L-Thyroxin beta,L-Thyroxine Roche,Levo-T,Levothroid,Levothyroid,Levothyroxin Deladande,Levothyroxin Delalande,Levothyroxine Sodium,Levoxine,Levoxyl,Lévothyrox,Novothyral,Novothyrox,O-(4-Hydroxy-3,5-diiodophenyl) 3,5-diiodo-L-tyrosine,O-(4-Hydroxy-3,5-diiodophenyl)-3,5-diiodotyrosine,Oroxine,Sodium Levothyroxine,Synthroid,Synthrox,Thevier,Thyrax,Thyroxin,Tiroidine,Tiroxina Leo,Unithroid,L Thyrox,L Thyroxin Henning,L Thyroxin beta,L Thyroxine,L Thyroxine Roche,Levo T,Thyroid Hormone, T4