Hyperphagia without obesity in septal-lesioned cocks

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  • Physiology & Behamor, Vol 20, pp 1 -6 . Pergamon Press and Brain Research Publ , 1978. Pnnted m the U.S A

    Hyperphagia Without Obesity in Septal-Lesioned Cocks

    B. ROBINZON, N SNAPIR AND PEREK

    Department of Ammal Science, Faculty of Agriculture, Hebrew Umverszty of Jerusalem, Rehovot, Israel

    (Received 8 Apnl 1977)

    ROBINZON, B, N. SNAPIR AND M PEREK Hyperphagta without obesity m septal-leszoned cocks PHYSIOL BEHAV 20(1) 1-6, 1978 - Placement of electrolytic lesions m the septal area (S A ) m chickens caused a marked increase m food retake which was not accompanied by development of obeuty. Oxygen consumpUon of the S A lesioned birds was s~gnifieantly higher than that of the controls Alemnophyhc-thyrotrople cell population of the adenohypophym and percentage of acUve follicles m the thyroid gland were higher for the S.A lesioned birds than for those of the control birds The S A lesions caused also an increase m the somatotroplc actmty The posslbthty that the previously found suppression effect of the olfactory bulbs on the thyrotroplc and somatotropic actavmes m the intact chicken is medmted vm the S A, ts discussed

    Septal area Hyperphagm Thyrotroplc aeUvlty Somatotroplc acUvlty

    PLACEMENT of bdateral septal lesions m geese by intra- cranml injections of 6-hydroxydopamme (6-OHDA) eh- cited a marked increase m food retake, which lasted for at least 60 days post operation, after which the experiment was terminated [22] In contrast to hyperphagla caused by basomedlal hypothalamus (BMH) lesions, no obesity devel- oped m the septal-lesIoned geese Sinular results were obtained with rats [17, 18, 19] The results with the geese are parallel to those reported on the chicken, m wluch removal of the olfactory bulbs (O B ) caused a marked increase m food Intake but without obesity [ 15] In this case it was proved that the surgical removal of the O.B ehclts a pnmary increase m thyroid activity followed by a compensatory increase In food retake [ 15 ]

    The purpose of the present investigatlon was to examine whether septal lesions in the chicken also lead to hyper- phagm unassocmted with obesity and if so, to record the accompanying physlologlcal phenomena

    METHOD

    A mmals

    Twenty White Leghorn cocks, 2 months old, were kept in mdmdual cages, fed a commercml breeder mash ad hb and subjected to 14 hr hght daily

    Surgical and Experimental Procedure

    Ten days after the begmmng of the experiment, the birds were dmded into two equal groups Anodal, DC bilateral electrolyhc lesions were placed in the septal area (S A ) of one group of birds using stainless steel electrodes passing 2 mA for 25 see The routine method for placing electrolytic lesions, using an x-ray atlas of the chicken brain [9,21 ] was apphed m thts experiment

    The foUowmg coordinates were chosen for reaching the SA AP=83mm, H=80mm, latera l=l 0mm

    Histological verification at the termination of the expen- ment revealed that In two birds the lesions were not located m the expected site and their data were omitted from the results

    The other group of birds were sham-operated and served as controls The experiment lasted for 280 days during which the following parameters were measured individual daffy food intake, and body weight, metatarsal length [20] and comb size [ 12] at 10-day intervals The obesity index was calculated based on the Lee Index [2,8] usmg the metatarsal length as representative of the body length as follows

    /nw 1000

    Metatarsal length

    The birds were penodlcally ejaculated for obtaining semen [4] Semen volume, sperm concentration [23] and motility [14], oxygen consumption at rest (RMR) and rectal temperature were measured penodlcally [ 15,16 ]

    Autopsy Procedure

    Prior to kalhng the birds, hepanmzed blood samples were drawn from the brachtal veto for deterrnmatlon of hemato- cnt and total plasma liplds [24] The birds were kalled by decapitation The brains of the lesioned birds were removed and fixed in 10% neutral Formahn The following were immedmtely removed, cleaned from adhenng tissues and weighed comb, abdominal adipose tissue, liver, testes, adrenals, thyroids and adenohypophysIs The liver, abdo- minal adipose tissue and a sample of the breast muscle were subjected to lipid extraction [ 10] and hpld percentage was determined using a gravimetric method

    Hzstologtcai Procedure

    Frozen frontal senal brain sections of 25 ~m thickness

  • 2 ROBINZON, SNAPIR AND PEREK

    were stained with thlonme The sectxons were subjected to mxcroscoplcal observation for locahzatlon of the lesion s~tes A representative sample from the center of the testes as well as the whole adenohypophysls, thyroid and adrenal glands were successively fixed in Boum-Hollande for 24 hr, carefully washed using &stalled water, and transferred to fresh 70% ETOH which was changed repeatedly The tlssues were routinely dehydrated and embedded m Tlssuemat Serial sections of 4 um thickness were tamed out Alternate sections of the adenohypophysls were alterna- twely stained with Alcxan Blue-PAS-Orange G [1,7] or with Wool green-Orange-G [13] The thyrmd, adrenal and testes sections were stained with Hematoxyhn-Eosln

    Statistical evaluation of the data was camed out using t-tests, and calculation of coefficients of correlation [3] The standard error tor each experimental group was calculated for the entire experimental period based on the following formula ~_~__E~ 2

    n

    RFSULTS

    Figure 1 shows schematlcal drawings of frontal brain sectmns [9] demonstrating representatively the location of the septal lemons As seen from Fig 2, a marked hyperpha- gla developed m the S A lesmned (S A L ) birds, as compared to the controls, and tins lasted until the end of the experimental period However, no differences were found m body weight between the two groups (Fig 3) Towards the end ot the experimental period the calculated obesity index ot the S A L cocks was lower than that of the controls, although the difference was not statlmcally slgmflcant (Fig 4) The coefficient of correlatmn between the dally food retake and the obesity index was positive for the control birds (r = 798, p

  • HYPERPHAGIA IN SEPTAL LESIONED COCKS 3

    2e

    ~ m 2~- -

    _D 1~- - ; "o 0 t41 ~- cont SE=012 =:

    SAL , SE=012 1 o 5oi do ,5ol

    Exper,mental per,od (days)

    FIG 3 Periodical changes m body weight of the control and S A L groups of birds Arrow indicates placement of lesion

    ilOO A - ~" SAL , SE:18

    Exper,mental per,od {days)

    FIG 5 Periodical changes m metatarsal length for the control and S A L groups of birds Arrow indicates placement of lesion

    i c >t

    e~ o

    @----O ont SE--28

    : ~SAL SB=34

    3(

    a

    E 0 u

    lg

    / /~ .- -~$AI.. 8E=15

    , Experlm~mtml per iod Cdaya)

    ! Exper,mental per,od {days) FIG 6 Penodncal changes m comb factor for the control and S A L groups of birds Arrow indicates placement of lesion

    FIG 4 Periodical changes m the obesnty index for the control and S A L groups of bnrds Arrow mdncates placement of lesion

    TABLE 1

    ADIPOSITY AND LINEAR GROWTH CRITERIA AT AUTOPSY TIME FOR THE CONTROL AND S A L GROUPS OF BIRDS

    Treatment Plasma Muscle

    Body total total Abdormnal achpose Ussue Lwer Metatarsal Obesity weqght hpnds hpnds Wew, ht Total hplds Weight Total hp]ds length index

    (g) (rag/100 ml) (%) (g) (%) (g) (%) (ram)

    Control 2240+111" 1612_+143 36+08 87+62 570_+ 82 336+24 60+03 1203+20 1086+18 n = lO (a)t (a) (a) (a) (a) (a) (a) (b) (a)

    SAL 2450-+115 1588-+1128 30-+02 205-+95 265-+142 360_+08 55-+02 1280-+1 1 1051_+23 n = 8 (a) (a) (a) (a) (a) (a) (a) (a) (a)

    *Mean _+ S E tF~ures which are not marked by the same letter are staUsUcally different from each other (/7

  • 4 ROBINZON, SNAP IR AND PEREK

    TABLE 2

    ADENOHYPOPHYSIS WEIGHT AND SELECTED CRITERIA FOR REPRODUCTIVE TRAITS FOR THE CONTROL AND S A L GROUPS OF BIRDS

    Treatment Adenc~ Semmtferous Total sperm

    hypophysls Testes Comb tubules Semen Spermatocnt per Spermatozoa weight wetght we~lht Hematocnt dmmeter volume ejaculaUon mottlity (rag) (g) (g) (%) O~m) (ml) (%) (I0 s) (0-7 degrees)

    Control 167+26" 302-+27 736-+37 413-+13 178-+18 071-+008 124-+42 3382-+154 62-+!2 n = I0 (a)? (a) (b) (a) (a) (a) (a) (a) (a)

    SAL 182-+28 3293-+282 987-+08 405-+12 169_+22 060-+009 123-+32 2788-+ 87 6 3 -*- 0 8 n = 8 (a) (a) (a) (a) (a) (a) (a) (b) (a)

    *Mean _+ S E tFtgures whtch are not marked by the same letter are statmUcally dtfferent from each other (p

  • HYPERPHAGIA IN SEPTAL LESIONED COCKS 5

    FIG 8 Photomicrographs of representaUve hlstologlcal sections of adenohypophysts of the control (a) and the S.A L (b) birds Alclan Blue-PAS-Orange G (x I100) Note the marked increase m alclano-

    phyhc-thyrotroplc cell populaUon m the S A L bird (arrows)

    tlon coefficient obtained between the daily food retake and the obesity Index m the S A L birds shows that the hyperphagla Induced by the S A destruction is secondary to the Increased energy expenditure, and possibly develops to prevent a decrease in adiposity below its normal set point The lower obesity index calculated for the lesioned birds - compared to that for the controls - may support this assumption

    Destruction of the S A In the rat ehclted similar results to those obtained with the chicken in respect to develop- ment of hyperphagla winch Is unaccompanied by an increase in body wetght [5, 17, 18, 19] In those Investlgatlons, however, no metabolic determinations were camed out

    It seems that the S A destruction in the cincken caused an increase m somatotrop~c ares acUwty as reflected m a longer metatarsus and a marked