The Ontogeny of Circadian Rhythms in the Rabbit

Abstract

The nursing rhythms of 14 rabbit does and the activity of 18 litters from birth to days 14-16 were monitored continuously, as were the circadian rhythms of different behavioral functions of 10 young rabbits from weaning until day 380 of life. The does gave birth 2 hr, 26 min +/- 2 hr, 8 min after lights-on in a light-dark cycle (LD 12:12). The first nursing occurred 20 hr, 30 min +/- 2 hr, 21 min after parturition. Does that had continuous access to the next boxes exhibited a regular once-a-day nursing rhythm; the nursing visits to the litters occurred during the dark phase (D). The nursing visits lasted 3 min, 42 sec +/- 25 sec. Nursing advanced during the first 10 days of lactation by an average of 42 +/- 16 min/day, and thus shifted to the first half of D. The pups anticipated nursing by a significant increase of activity, which was established between days 1 and 5 of life. In two does, the nursing rhythm split into two nursing visits per day, one during D and one during the light phase (L). When scheduled to nurse at an "artificial" phase in L with T = 24 hr, the pups' anticipatory activity was entrained by the 24-hr nursing rhythm. During a 48-hr fast, the elevated activity persisted around the phase of prior nursing time, demonstrating that it was controlled by an endogenous oscillator entrained by the zeitgeber of maternal nursing. Of 10 weanlings, 6 first exhibited a trimodal rhythm, which turned bimodal within 3-6 days. Stable entrainment by the external LD zeitgeber was attained by about days 45-80, and full nocturnality was attained by about days 200-250 after weaning. Having attained steady-state conditions, 7 of 10 rabbits exhibited a stable unimodal, nocturnal rhythm in each of the five functions, while the other 3 retained a bimodal rhythm.

Immediate postnatal sucking in the rabbit: Its influence on pup survival and growth

“…Indeed, since the peak times for parturition and for the first return of the doe are in the morning hours and in the hours just before sunrise the next day, the period elapsing between the first two sucking opportunities is about 16-20 h (with a 4-32 h range [39]; or a 16-26 h range [25]). Thus, the rabbit offers an interesting opportunity to examine the impact of the initial colostrum intake on individual differences in neonatal adaptation.…”

Distribution of AVP and Ca2+-dependent PKC-isozymes in the suprachiasmatic nucleus of the mouse and rabbit

“…The choice of mice and rabbits was based on the differences in entrainment to the LD-cycle and the number of AVP-ir neurons in the SCN between the two species. Whereas mice are exclusively nocturnal, rabbits are only predominantly nocturnal under undisturbed conditions [12][13][14][15], and AVP-ir cells in the mouse SCN seem to outnumber those in the rabbit SCN [4,37].…”

Comportamiento materno y bienestar de la coneja doméstica y silvestre y su camada

“…Además, las dos hormonas clásicas de la lactancia, es decir, la prolactina y la oxitocina muestran una liberación fásica y breve. En cada episodio de succión, que dura entre 3 y 5 minutos (González-Mariscal et al, 1994), y ocurre sólo una vez cada 24 horas dentro del nido (Jilge, 1993(Jilge, y 1995González-Mariscal et al, 2013b), se observa la secreción má-xima de oxitocina y prolactina (Tabla 1). Sin embargo, el brusco incremento en la con-Figura 1.…”

“…Existe evidencia que sugiere que la oxitocina participa en la regulación de un aspecto particular de la conducta maternal: su temporalidad. Normalmente las conejas amamantan a sus crías con periodicidad circadiana, es decir, una vez cada 24 horas (Jilge, 1993(Jilge, y 1995González-Mariscal et al, 2013b). Sin embargo, si el tamaño de la camada es pequeño (menor a 6 gazapos) se pierde la periodicidad circadiana y las madres entran a la caja nido muchas veces al día (González-Mariscal et al, 2013b).…”