Evidence for the involvement of dopamine and 5-hydroxytryptamine in the regulation of the preovulatory release of luteinizing hormone in the domestic hen

1989 ◽  
Vol 76 (2) ◽  
pp. 205-213 ◽  
Author(s):  
P.J. Sharp ◽  
R.T. Talbot ◽  
M.C. Macnamee
Keyword(s):  
Luteinizing Hormone ◽  
Domestic Hen

EFFECTS OF AN INTERMITTENT LIGHTING SCHEDULE ON THE TIME OF EGG-LAYING AND THE LEVELS OF LUTEINIZING HORMONE, PROGESTERONE AND CORTICOSTERONE IN THE PLASMA OF THE DOMESTIC HEN

1981 ◽  
Vol 91 (3) ◽  
pp. 375-383 ◽  
Author(s):  
MICHELE DUPLAIX ◽  
JOHN WILLIAMS ◽  
PIERRE MONGIN
Keyword(s):  
Luteinizing Hormone ◽  
Egg Laying ◽  
Normal Pattern ◽  
The Hours ◽  
Domestic Hen

The use of a complex lighting schedule consisting of five blocks of light and five alternating periods of darkness every 24 h completely abolished the normal pattern of egg-laying characteristic of the domestic hen. Animals tended to lay continuously and not in clutch sequences. Ovipositions were not restricted to an 8- to 10-h period of the day, instead they occurred at any time of the solar day with slightly more occurring during the hours of darkness. The preovulatory discharge of LH was not restricted to an 8- to 10-h 'open period' and the interval between the peak values of LH in the plasma and the time of lay of the corresponding egg was 32·3 h, i.e. identical to the interval found using a normal lighting schedule of 14 h light: 10 h darkness. There were some indications that minor fluctuations in the concentrations of LH in plasma occurred rhythmically with the changes in illumination, but the concentrations of progesterone showed only a single, preovulatory peak. The concentrations of corticosterone in the plasma were high and showed marked fluctuations but this did not appear to affect either the levels of progesterone or the time of ovulation.

Evidence of a photoinducible phase for the release of luteinizing hormone in the domestic hen

1982 ◽  
Vol 94 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Susan C. Wilson
Keyword(s):  
Plasma Concentration ◽  
Luteinizing Hormone ◽  
Control Group ◽  
Abrupt Increase ◽  
Threefold Increase ◽  
Main Period ◽  
Lh Release ◽  
Lh Releasing Hormone ◽  
Lh Secretion ◽  
Domestic Hen

Hens raised on a schedule of 8 h light: 16 h darkness (8L : 16D) were exposed to changes in photoperiod at 17 or 18 weeks of age. These involved exposure to either an abrupt increase in photoperiod to 16 h per day or to skeleton photoperiods comprising a main period of 7·75 or 4 h light together with a pulse of 15 min or 4 h light provided at different times during the period of darkness. An increase in photoperiod to 16 h per day stimulated a two- to threefold increase in the plasma concentration of LH within 1–3 days. Interruption of a 7·75L : 16D schedule by 15 min light between 13·75 and 19·75 h after the beginning of the main photoperiod stimulated LH secretion in the immature and adult hen and a higher rate of lay than that of the 8L : 16D control group. There was a significant (P < 0·01) correlation between the concentration of LH in the plasma and the rate of lay. The photostimulated rise in the plasma concentration of LH in the immature hen was not associated with any increase in the responsiveness of the pituitary gland to LH releasing hormone. Of the treatments in which a 15-min pulse of light was provided, the schedules of 7·75L : 10D : 0·25L : 6D and 7·75L : 12D : 0·25L : 4D, which were most effective in stimulating LH release, appeared to be interpreted as 0·25L : 6D : 7·75L : 10D and 0·25L : 4D : 7·75L : 12D respectively. In hens given a 7·75-h main photoperiod, in which phase-reversal did not occur, 15 min light was most stimulatory when given 14–16 h after the begining of the main photoperiod, although not to the same extent as an increase in photoperiod to 16 h per day. In hens for which an 8-h complete photoperiod was changed to a 4-h main photoperiod, together with a further 4-h pulse of light provided at different times during the period of darkness, the period of maximum sensitivity to light occurred 11 h after the onset of the main photoperiod and at this time light stimulated LH release to the same extent as an increase in complete photoperiod from 8 to 16 h per day. Results of this study suggest that the period of maximum photosensitivity shifts its phase after a change in the form of photoperiod and is primarily entrained to dusk.

Changes in Hypothalamic Monoamine Concentrations Accompany the Progesterone-Induced Release of Luteinizing Hormone in the Domestic Hen

1982 ◽  
Vol 35 (5) ◽  
pp. 359-362 ◽  
Author(s):  
P.G. Knight ◽  
P.T. Francis ◽  
R.B. Holman ◽  
R.T. Gladwell
Keyword(s):  
Luteinizing Hormone ◽  
Domestic Hen

Evidence for the involvement of central catecholaminergic mechanisms in mediating the preovulatory surge of luteinizing hormone in the domestic hen

1982 ◽  
Vol 94 (2) ◽  
pp. 295-304 ◽  
Author(s):  
P. G. Knight ◽  
S. C. Wilson ◽  
R. T. Gladwell ◽  
F. J. Cunningham
Keyword(s):  
Steady State ◽  
Luteinizing Hormone ◽  
Pharmacological Treatments ◽  
Ovulatory Cycle ◽  
Lh Surge ◽  
Dopaminergic Mechanisms ◽  
Lh Release ◽  
Noradrenaline And Adrenaline ◽  
Domestic Hen ◽  
Catecholaminergic Mechanisms

The effects of various pharmacological treatments, designed to perturb central catecholaminergic neurotransmission, on the pattern of LH release during the preovulatory period in the domestic hen were studied. Treatment of hens with either l-dihydroxyphenylalanine or diethyldithiocarbamate which raised the concentration of dopamine in the hypothalamus by 42 and 110% respectively, or with apomorphine, attenuated the preovulatory surge of LH. In contrast, treatment with either α-methyl-p-tyrosine which produced a 65% decline in the concentration of dopamine in the hypothalamus without affecting the concentrations of noradrenaline or adrenaline or treatment with pimozide did not affect the LH surge. While treatment with propranolol was similarly ineffective, phenoxybenzamine attenuated the LH surge to a marked extent. These observations suggest that the preovulatory surge of LH in the hen is influenced by facilitatory α-adrenergic and inhibitory dopaminergic mechanisms. Evidence to corroborate these findings was sought by determining the steady-state concentrations of dopamine, noradrenaline and adrenaline in five discrete diencephalic regions of the hen throughout the ovulatory cycle.

CHANGES IN PLASMA CONCENTRATIONS OF LUTEINIZING HORMONE AFTER INJECTION OF PROGESTERONE AT VARIOUS TIMES DURING THE OVULATORY CYCLE OF THE DOMESTIC HEN (GALLUS DOMESTICUS)

1975 ◽  
Vol 67 (1) ◽  
pp. 59-70 ◽  
Author(s):  
SUSAN C. WILSON ◽  
P. J. SHARP
Keyword(s):  
Luteinizing Hormone ◽  
Plasma Concentrations ◽  
Gallus Domesticus ◽  
Ovulatory Cycle ◽  
Lh Surge ◽  
Incremental Change ◽  
The Mean ◽  
Domestic Hen

SUMMARY Changes in plasma LH concentrations after i.m. injections of 0·5 mg progesterone/kg at various stages of the ovulatory cycle were measured by radioimmunoassay. Four types of response were observed. (1) When the steroid was injected between 4 h after and 12 h before an ovulation, LH levels started to rise after 15–45 min and reached peak values within 90–120 min. The mean maximal incremental change in the level of LH was 1·58 ± 0·10 (s.e.m.) ng/ml (n = 37). (2) In contrast, when progesterone was injected 12–8 h before ovulation, i.e. immediately before a spontaneous pre-ovulatory LH surge, the resulting mean maximal incremental change in LH level, 0·79 ± 0·12 ng/ml (n = 9), was significantly smaller (P < 0·001). (3) If progesterone was injected 8–4 h before ovulation, i.e. when pre-ovulatory LH levels were rising, they immediately started to rise more rapidly and reached peak values within 45 min. The maximal incremental change in the level of LH under these circumstances, 2·34 ± 0·20 ng/ml (n = 12), was significantly greater (P < 0·001 in both cases) than the changes observed in the responses 1 and 2 described above. (4) Levels of LH generally showed no incremental change in response to injections of progesterone given 4–0 h before ovulation, i.e. when pre-ovulatory LH levels were falling. It was concluded that the type of change in plasma LH levels induced by progesterone depended upon the stage of the ovulatory cycle at which the steroid was injected.

An investigation of diurnal and cyclic changes in the secretion of luteinizing hormone in the domestic hen

1983 ◽  
Vol 98 (1) ◽  
pp. 137-145 ◽  
Author(s):  
S. C. Wilson ◽  
R. C. Jennings ◽  
F. J. Cunningham
Keyword(s):  
Luteinizing Hormone ◽  
Diurnal Rhythm ◽  
Laying Hen ◽  
Ovulatory Cycle ◽  
Pronounced Increase ◽  
Threefold Increase ◽  
Steep Decline ◽  
Cyclic Changes ◽  
Lh Secretion ◽  
Domestic Hen

The characteristics of the diurnal rhythm in the concentration of LH in plasma of the domestic hen varied according to age and duration of photoperiod. A pronounced increase in LH was observed at the onset of darkness in immature hens whether maintained on schedules of 16 h light:8 h darkness (16L:8D) or 8L:16D. During weeks 4·5–15 or −17·5 raised concentrations of LH were maintained until 6 and 12 h after the onset of darkness in hens held on 16L:8D and 8L:16D respectively. By 19 weeks of age the diurnal rhythm of LH secretion had changed to resemble more closely that observed in the laying hen. An increase in the concentration of LH in plasma at the onset of darkness was of comparatively short duration and gave way, within 2–3 h, to a steep decline before a further slight increase in LH, which tended to occur at 11–14 h after the onset of darkness. Superimposed on this diurnal rhythm of LH secretion in the laying hen were a one- to threefold increase in the concentration of LH during 8–4 h before ovulation and a much less pronounced increase in LH during 0–8 h after ovulation. The pattern of changes in the concentration of LH in plasma during the ovulatory cycle was not modified by the repeated withdrawal of blood at intervals of 2 h.

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